relationship of antioxidants with qualitative changes in local cultivars of loquat...

i

RELATIONSHIP OF ANTIOXIDANTS WITH QUALITATIVE CHANGES IN

LOCAL CULTIVARS OF LOQUAT (Eriobotrya japonica Lindl.) FRUIT DURING

STORAGE

Attiq Akhtar (03-arid-373)

Department of Horticulture Faculty of Crop and Food Sciences

Pir Mehr Ali Shah Arid Agriculture University

Rawalpindi, Pakistan 2009

ii

RELATIONSHIP OF ANTIOXIDANTS WITH QUALITATIVE CHANGES IN

LOCAL CULTIVARS OF LOQUAT (Eriobotrya japonica Lindl.) FRUIT DURING

STORAGE

By

Attiq Akhtar

(03-arid-373)

A thesis submitted in partial fulfillment of the requirements for the degree of

DOCTOR OF PHILOSOPHY

IN

HORTICULTURE

Department of Horticulture Faculty of Crop and Food Sciences

Pir Mehr Ali Shah Arid Agriculture University

Rawalpindi, Pakistan 2009

iii

CERTIFICATION

I hereby undertake that this research is an original one and no part of this thesis falls

under plagiarism. If found otherwise, at any stage, I will be responsible for the

consequences.

Name: Attiq Akhtar Signature: ______________

Registration No. : 03-arid-373 Date:

Certified that the contents and form of thesis entitled “Relationship of antioxidants with

qualitative changes in local cultivars of Loquat (Eriobotrya japonica lindl. ) fruit

during storage” submitted by “Mr. Attiq Akhtar” has been found satisfactory for

requirement of the degree.

Supervisor: __________________________ (Dr. Nadeem Akhtar Abbasi) Member: __________________________ (Dr. Ishfaq Ahmad Hafiz) Member: __________________________ (Dr. Ghazala Kaukab) Chairman: ________________________ Dean: ____________________________ Director Advanced Studies: ______________________

iv

DEDICATED TO

MY PARENTS

v

CONTENTS

PAGE List of Figures vi

List of Tables viii

Abbreviations xiii

Acknowledgements xv

1 INTRODUCTION 1

1.1 LOQUAT 1

1.2 ORIGIN AND DISTRIBUTION 1

1.3 LOQUAT VARIETIES 1

1.4 LOQUAT AREA AND PRODUCTION 3

1.5 NUTRITION AND MEDICINAL IMPORTANCE OFLOQUAT

3

1.6 ECONOMIC VALUE 4

2 EFFECT OF POLYETHYLENE PACKAGES ON KEEPING QUALITY OF LOQUAT.

8

2.1 ABSTRACT 8

2.2 INTRODUCTION 9

2.3 REVIEW OF LITERATURE 10

2.3.1 Loquat Postharvest Handling 10

2.3.2 Modified Atmosphere Packaging (MAP) 12

2.3.3 Polyethylene Film Packaging 14

2.3.4 Antioxidants 15

2.3.5 Free Radicals 16

2.3.6 Antioxidants In Relation To Shelf life of Fruits and Vegetables

18

2.3.7 Superoxide Dismutase (SOD) 20

2.3.8 Catalase (CAT) 22

2.4 MATERIALS AND METHODS 22

2.4.1 Weight Loss 24

vi

2.4.2 Firmness 24

2.4.3 Total Soluble Solids 25

2.4.4 Sugars 25

2.4.4.1 Reducing sugars 25

2.4.4.2 Total sugars 26

2.4.4.3 Non reducing sugars 26

2.4.5 Titratable Acidity 26

2.4.6 Total Soluble Protein 27

2.4.7 Extraction of Enzymes 28

2.4.7.1 Superoxide Dismutase (SOD) Assay 28

2.4.7.2 Catalase (CAT) Assay 29

2.4.7.3 Peroxidase (POD) Assay 29

2.4.8 Ascorbic Acid (Vitamin C) 29

2.4.9 Radical Scavenging Activity (RSA) 30

2.4.10 Polyphenol Oxidase (PPO) Assay 30

2.4.11 Total Phenolic Content 31

2.4.12 Browning Index 32

2.4.13 Relative Electrical Conductivity (REC) 32

2.5 STATISTICAL ANALYSIS 33

2.6 RESULTS AND DISCISSION 34

2.6.1 Effect on Weight Loss 34

2.6.2 Effect on Firmness 37

2.6.3 Effect on Total Soluble Solids 41

2.6.4 Effect on Sugars 45

2.6.4.1 Effect on total sugars 45

2.6.4.2 Effect on reducing sugars 45

2.6.4.3 Effect on non reducing sugars 50

2.6.5 Effect on Titratable Acidity 52

2.6.6 Effect on SOD Activity 56

vii

2.6.7 Effect on Catalase Activity 61

2.6.8 Effect on POD Activity 64

2.6.9 Effect on Ascorbic Acid Content 69

2.6.10 Effect on Radical Scavenging Activity 72

2.6.11 Effect on PPO Activity 77

2.6.12 Effect on Total Phenolic Content 80

2.6.13 Effect on Browning Index 86

2.6.14 Effect on Relative Electrical Conductivity 88

2.7 CONCLUSION 92

3 EFFECT OF CALCIUM CHLORIDE TREATMENTS ON STORAGE LIFE OF LOQUAT

93

3.1 ABSTRACT 93

3.2 INTRODUCTION 94


3.3.1 Postharvest Physiology 95

3.3.2 Dipping Treatments 97

3.3.3 Calcium Chloride 97

3.3.4 Electrolyte Leakage 99



3.6 RESULTS AND DISCUSSION 104








viii











3.7 CONCLUSION 159

4 EFFECT OF ANTI BROWNING AGENTS ON THE KEEPING QUALITY OF LOQUAT FRUIT

160

4.1 ABSTRACT 160

4.2 INTRODUCTION 161


4.3.1 Chemicals For Extending Postharvest Life 161

4.3.2 Ascorbic Acid 162

4.3.3. Citric Acid 164

4.3.4 Peroxidase 166

4.3.5 Phenolic Compounds and Polyphenol Oxidase (PPO) 167

4.3.6 Role of Phenolics in Enzymatic Browning 170

4.3.7 Substrates of PPO 173

4.3.8 Sources of PPO 174



4.6 RESULTS AND DISCUSSION 177


ix

















4.7 CONCLUSION 251

GENERAL DISCUSSION 253

SUMMARY 265

RECOMMENDATIONS 267

LITERATURE CITED 268

x

LIST OF FIGURES

FIG. NO PAGE

1 Effect of polyethylene packaging on weight loss in loquat 35

2 Effect of polyethylene packaging on firmness in loquat 38

3 Effect of Polyethylene packing on total soluble solids in loquat 42

4 Effect of polyethylene packaging on total sugars in loquat 46

5 Effect of polyethylene packaging on titratable acidity in loquat 53

6 Effect of polyethylene packaging on SOD activity in loquat 57

7 Effect of polyethylene packages on catalase activity in loquat 62

8 Effect of polyethylene packaging on POD activity browning index in loquat

65

9 Effect of polyethylene packaging on ascorbic acid content in loquat

70

10 Effect of polyethylene packaging on radical scavenging activity in loquat

74

11 Effect of polyethylene packaging on PPO activity in loquat 78

12 Effect of polyethylene packaging on total phenolics in loquat 82

13 Effect of polyethylene packaging on browning index in loquat 85

14 Effect of polyethylene packaging on relative electrical conductivity in loquat

89

15 Effect of calcium chloride on weight loss in loquat 105

16 Effect of calcium chloride on firmness in loquat 108

17 Effect of calcium chloride agents on total soluble solids in loquat 111

18 Effect of calcium chloride treatments on totals sugars in loquat 115

19 Effect of calcium chloride on titratable acidity in loquat 122

20 Effect of calcium chloride agents on SOD activity in loquat 125

21 Effect of calcium chloride on catalase activity in loquat 129

22 Effect of calcium chloride on POD activity in loquat 134

23 Effect of calcium chloride agents on ascorbic acid content in

loquat

137

24 Effect of calcium chloride on radical scavenging activity in loquat

141

xi

25 Effect of calcium chloride agents on PPO activity in loquat 145

26 Effect of calcium chloride agents on total phenolics in loquat 148

27 Effect of calcium chloride agents on browning index in loquat 152

28 Effect of calcium chloride agents on relative electrical conductivity in loquat

156

29 The ascorbate-glutathione cycle 163

30 Reactions catalyzed by polyphenol oxidases 172

31 Effect of antibrowning agents on weight loss in loquat 178

32 Effect of antibrowning agents on firmness in loquat 183

33 Effect of antibrowning agents on total soluble solids in loquat 188

34 Effect of antibrowning agents on total sugars in loquat 193

35 Effect of antibrowning agents on titratable acidity in loquat 202

36 Effect of antibrowning agents on SOD activity in loquat 207

37 Effect of antibrowning agents on catalase activity in loquat 212

38 Effect of Anti browning agents on POD activity in loquat 217

39 Effect of antibrowning agents on ascorbic acid content in loquat 222

40 Effect of antibrowning agents on radical scavenging activity in loquat

226

41 Effect of antibrowning agents on PPO activity in loquat 232

42 Effect of antibrowning agents on total phenolics in loquat 237

43 Effect of antibrowning agents on browning index in loquat 243

44 Effect of antibrowning agents on relative electrical conductivity in loquat

248

xii

TABLES

TABLE NO PAGE

1.1 Effect of polyethylene packaging on weight loss in Surkh

loquat 36

1.2 Effect of polyethylene packaging on weight loss in Sufaid loquat

36

2.1 Effect of Polyethylene packing on firmness in Surkh loquat 39

2.2 Effect of Polyethylene packing on firmness in Sufaid loquat

39

3.1 Effect of polyethylene packaging on total soluble solids in Surkh loquat

43

3.2 Effect of polyethylene packaging on total soluble solids in Sufaid loquat

43

4.1 Effect of polyethylene packaging on total sugars in Surkh loquat

47

4.2 Effect of polyethylene packaging on total sugars in Sufaid loquat

47

5.1 Effect of polyethylene packaging on reducing sugars in Surkh loquat

48

5.2 Effect of polyethylene packaging on reducing sugars in Sufaid loquat

48

6.1 Effect of polyethylene packaging on non reducing sugars in Surkh loquat

49

6.2 Effect of polyethylene packaging on non reducing sugars in Sufaid loquat

49

7.1 Effect of polyethylene packaging on titratable acidity in Surkh loquat

54

7.2 Effect of polyethylene packaging on titratable acidity in Sufaid loquat

54

8.1 Effect of polyethylene packaging on SOD activity in Surkh loquat

58

8.2 Effect of polyethylene packaging on SOD activity in Sufaid loquat

58

9.1 Effect of polyethylene packaging on catalase activity in Surkh loquat

63

9.2 Effect of polyethylene packaging on catalase activity in Sufaid loquat

63

10.1 Effect of polyethylene packaging on POD activity in Surkh loquat

66

xiii

10.2 Effect of polyethylene packaging on POD activity in Sufaid loquat

66

11.1 Effect of polyethylene packaging on ascorbic acid content in Surkh loquat

71

11.2 Effect of polyethylene packaging on ascorbic acid content in Sufaid loquat

71

12.1 Effect of polyethylene packaging on radical scavenging activity in Surkh loquat

75

12.2 Effect of polyethylene packaging on radical scavenging activity in Sufaid loquat

75

13.1 Effect of polyethylene packages on PPO activity in Surkh loquat

79

13.2 Effect of polyethylene packages on PPO activity in Sufaid loquat

79

14.1 Effect of polyethylene packaging on total phenolics in Surkh loquat

83

14.2 Effect of polyethylene packaging on total phenolics in Sufaid loquat

83

15.1 Effect of polyethylene packaging on browning index Surkh loquat

87

15.2 Effect of polyethylene packaging on browning index in Sufaid loquat

87

16.1 Effect of polyethylene packaging on relative electrical conductivity in Surkh loquat

90

16.2 Effect of polyethylene packaging on relative electrical conductivity in Sufaid loquat

90

17.1 Effect of calcium chloride on weight loss in Surkh loquat 106

17.2 Effect of calcium chloride on weight loss in Sufaid loquat 106

18.1 Effect of calcium chloride agents on firmness in Surkh loquat

109

18.2 Effect of calcium chloride agents on firmness in Sufaid loquat

109

19.1 Effect of calcium chloride on total soluble solids in Surkh loquat

112

19.2 Effect of calcium chloride on total soluble solids in Sufaid loquat

112

20.1 Effect of calcium chloride agents on totals sugars in Surkh loquat

116

20.2 Effect of calcium chloride agents on totals sugars in Sufaid loquat

116

21.1 Effect of calcium chloride on reducing sugars in Surkh loquat

117

xiv

21.2 Effect of calcium chloride on reducing sugars in Sufaid loquat

117

22.1 Effect of calcium chloride on non reducing sugars in Surkh loquat

118

22.2 Effect of calcium chloride on non reducing sugars in Sufaid loquat

118

23.1 Effect of calcium chloride on titratable acidity in Surkh loquat

123

23.2 Effect of calcium chloride on titratable acidity in Sufaid loquat

123

24.1 Effect of calcium chloride agents on SOD activity in Surkh loquat

126

24.2 Effect of calcium chloride agents on SOD activity in Sufaid loquat

126

25.1 Effect of calcium chloride on catalase activity in Surkh loquat

130

25.2 Effect of calcium chloride on catalase activity in Sufaid loquat

130

26.1 Effect of calcium chloride agents on POD activity in Surkh loquat

135

26.2 Effect of calcium chloride agents on POD activity in Sufaid loquat

135

27.1 Effect of calcium chloride treatments on ascorbic acid content in Surkh loquat

138

27.2 Effect of calcium chloride treatments on ascorbic acid content in Sufaid loquat

138

28.1 Effect of calcium chloride agents on radical scavenging activity in Surkh loquat

142

28.2 Effect of calcium chloride agents on radical scavenging activity in Sufaid loquat

142

29.1 Effect of calcium chloride on PPO activity in Surkh loquat 146

29.2 Effect of calcium chloride on PPO activity in Sufaid loquat 146

30.1 Effect of calcium chloride on total phenolics in Surkh loquat

149

30.2 Effect of calcium chloride on total phenolics in Sufaid loquat

149

31.1 Effect of calcium chloride agents on browning index in Surkh loquat

153

31.2 Effect of calcium chloride agents on browning index in Sufaid loquat

153

32.1 Effect of calcium chloride agents on relative electrical conductivity in Surkh loquat

157

xv

32.2 Effect of calcium chloride agents on relative electrical conductivity in Sufaid loquat

157

33.1 Effect of antibrowning agents on weight loss in Surkh loquat

178

33.2 Effect of antibrowning agents on weight loss in Sufaid loquat

180

34.1 Effect of antibrowning agents on firmness in Surkh loquat 184

34.2 Effect of antibrowning agents on firmness in Sufaid loquat 185

35.1 Effect of antibrowning agents on total soluble solids in Surkh loquat

189

35.2 Effect of antibrowning agents on total soluble solids in Sufaid loquat

190

36.1 Effect of antibrowning agents on total sugars in Surkh loquat

194

36.2 Effect of antibrowning agents on total sugars in Sufaid loquat

195

37.1 Effect of antibrowning agents on reducing sugars in Surkh loquat

196

37.2 Effect of antibrowning agents on reducing sugars in Sufaid loquat

197

38.1 Effect of antibrowning agents on non reducing sugars in Surkh loquat

198

38.2 Effect of antibrowning agents on non reducing sugars in Sufaid loquat

199

39.1 Effect of antibrowning agents on titratable acidity in Surkh loquat

203

39.2 Effect of antibrowning agents on titratable acidity in Sufaid loquat

204

40.1 Effect of antibrowning agents on SOD activity in Surkh loquat

208

40.2 Effect of antibrowning agents on SOD activity in Sufaid loquat

209

41.1 Effect of antibrowning agents on catalase activity in Surkh loquat

213

41.2 Effect of antibrowning agents on catalase activity in Sufaid loquat

214

42.1 Effect of antibrowning agents on POD activity in Surkh loquat

218

42.2 Effect of antibrowning agents on POD activity in Sufaid loquat

219

43.1 Effect of antibrowning agents on ascorbic acid content in Surkh loquat

223

xvi

43.2 Effect of antibrowning agents on ascorbic acid content in Sufaid loquat

224

44.1 Effect of antibrowning agents on radical scavenging activity in Surkh loquat

227

44.2 Effect of antibrowning agents on radical scavenging activity in Sufaid loquat

228

45.1 Effect of Anti browning agents on PPO activity in Surkh loquat

233

45.2 Effect of Anti browning agents on PPO activity in Sufaid loquat

234

46.1 Effect of antibrowning agents on total phenolics in Surkh loquat

238

46.2 Effect of antibrowning agents on total phenolics in Sufaid loquat

239

47.1 Effect of antibrowning agents on browning index in Surkh loquat

244

47.2 Effect of antibrowning agents on browning index in Sufaid loquat

245

48.1 Effect of antibrowning agents on relative electrical conductivity in Surkh loquat

249

48.2 Effect of antibrowning agents on relative electrical conductivity in Sufaid loquat

250

xvii

ABBREVIATIONS

% percent ° degree °C degree Celsius µg microgram AA Ascorbic acid BI Browning index CA Citric acid Ca2

+ Calcium ion CaCl2 Calcium chloride CAT Catalase cm centimeter CO2 Carbon dioxide. CRD Completely randomized design. Cu Copper cv cultivar DPPH 2,2-diphenyl-1-picryl-hydrazyl EC Electrical conductivity EDTA ethylenediaminetetraacetic acid et al., et alia FAO food and agriculture organization Fe Ferrous FeSOD iron superoxide dismutase Fig. Figure FW Fresh weight g gram(s) GOP Government of Pakistan H2O2 Hydrogen peroxide HDPE High density polyethylene HDPEP High density polyethylene (perforated) kg kilogram kgf kilogram force l litre LDPE Low density polyethylene LDPEP Low density polyethylene (perforated) LOOH lipid peroxide LSD Least significant difference MAP Modified atmosphere packaging MeOH methanol mg milligram min minute

xviii

mm millimeter mM millimolar(s) Mn Manganese MnSOD manganese superoxide dismutase NADH nicotinamide adenine dinucleotide, reduced NADPH nicotinamide adenine dinucleotide phosphate, reduced NaOH Sodium hydroxide NBT nitroblue tetrazolium ns non significant NWFP North western frontier province O2 Oxygen. O2

- Superoxide anion OD optical density OFR Oxygen free radical OH- Hydroxyl radical P Probability PAL Phenylalanine ammonialyase PE Polyethylene POD Peroxidase PPO Polyphenol oxidase PVPP Polyvinylpolypyrrolidone r correlation coefficient RH unsaturated fatty acid ROOH lipid hydroperoxide ROO• alkylperoxyl radical (used for lipid ROO• unless otherwise mentioned) ROS Reactive oxygen species RO• alkoxyl radical rpm rounds per minute R• alkyl radical SOD superoxide dismutase T Treatment TA titratable acidity TP Total phenolics TSS total soluble solids UV ultraviolet v/v volume by volume Zn Zinc ZnSOD zinc superoxide dismutase

xix

ACKNOWLEDGEMENTS

I avail this opportunity to bow my head before Almighty ALLAH in humility,

The source of knowledge and wisdom, for blessing me the good health, strength and

perseverance needed to complete this study.

I feel great pleasure in expressing my sincerest thanks to my supervisor Prof. Dr.

Nadeem Akhtar Abbasi, Chairman, Department of Horticulture for his skillful

supervision, sincere support and inspiring guidance throughout this study. This thesis

would not have been possible to finish without his input and encouragement throughout

this study. I sincerely respect him for his devotion to work, co-operation and

encouragement during the study period.

I am also very grateful to members of my supervisory committee, Dr. Ishfaq

Ahmad Hafiz, Associate Professor, Horticulture and Dr. Ghazala Kaukab, Associate

Professor, Biochemistry for their valued suggestions and constructive criticisms during

the course of this study.

My very special thanks to Mr. Tauqeer Ahmad, Lecturer, Horticulture, for his

kind help, accommodative behavior and suggestions throughout the duration of this

study. I found him very generous, supportive and always available in time of need.

I wish to thank my colleagues in the lab as well as all my friends especially

Dr. Azhar Hussain Naqvi, Javed Tareen and Dr. Rizwan Khalid for their moral

support and judicious advise during the course of this study.

I can never forget the assistance of Dr. Tariq Siddique, Assistant Professor,

Department of Soil Science and Pro. Dr. Riaz Ahmad , Director Quality Control for

xx

their sympathetic attitude, helpful comments and corrections that they provided me

during the final stages of this thesis.

I express my thanks to Higher Education Commission of Pakistan for providing

me the financial support through Ph. D. Indigenous scholarship which made this study

possible.

Last, but not least, I am very indebted to my family for their patience, support and

encouragement throughout my study and whose hand always rose in prayers for me. My

deepest gratitude, I reserve for my wife whose patience and understanding for having put

up with me in my efforts to get this degree completed. The good wishes of my children

for my success are unforgettable and worthy of sincere acknowledgements.

(Attiq Akhtar)

xxi

EFFECT OF CALCIUM CHLORIDE TREATMENTS ON QUALITY CHARACTERISTICS OF LOQUAT

FRUIT DURING STORAGE

ATTIQ AKHTAR, NADEEM AKHTAR ABBASI AND AZHAR HUSSAIN

Department of Horticulture, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi.

E-mail: [email protected]

Abstract

In order to study the effectiveness of Calcium chloride treatments on postharvest quality and storage behavior of “Surkh” cultivar of loquat, fruit was dipped in three concentrations (1%, 2% and 3%) of Calcium chloride for two minutes and stored in soft board cartons at 4˚C in a cold store for 10 weeks period. The fruit was harvested at mature ripe stage, clipped, sorted and washed before applying the treatments. Changes in weight loss, firmness, total soluble solids (TSS), browning index (BI), ascorbic acid, titratable acidity (TA) and relative electrical conductivity (REC) were studied. One percent CaCl2 did not affect quality parameters of the fruit compared to control treatment, whereas, 2% and 3% CaCl2 retained maximum firmness, TSS, ascorbic acid content reduced browning index (BI) , relative electrical conductivity (REC) and weight loss up to 4-5 weeks. Introduction

Loquat (Eriobotrya japonica Lindl.) is a popular fruit in Pakistan. Generally, 2 local cultivars viz., “Surkh” and “Sufaid” are widely grown in the North Western Frontier Province (NWFP) and Punjab province. The “Surkh” cultivar is nearly pear shaped with orange colored skin and flesh while “Sufaid” cultivar has light yellow skin with creamy white flesh and is less acidic (Hussain et al., 2007). Loquat has a short shelf life and its quality deteriorates rapidly after harvest. Though postharvest quality of a produce after harvest cannot be improved, it is possible to reduce the rate of quality loss. The rate of deterioration (physiological decay) of fruit is directly related to the respiration rate (Kader et al., 1989). Surface treatments delay physiological decay in fruit tissues, stabilize the fruit surface and prevent degradation that affect the quality of the product. They also rinse the enzymes and substrates released from injured cells during cutting operations from the product surface. Infiltrated calcium in fresh apples has been shown to bind the cell wall and middle lamellae, where major influences on firmness are expected (Glenn & Poovaiah, 1990). Pre- and postharvest application of calcium may delay senescence in fruits with no detrimental effect on consumer acceptance (Lester & Grusak, 2004). Exogenously applied calcium stabilizes the plant cell wall and protects it from cell wall degrading enzymes (White & Broadley, 2003). Studies have shown that the rate of senescence often depends on the calcium status of the tissue and by increasing calcium levels, various parameters of senescence such as respiration, protein, chlorophyll content and membrane fluidity are altered (Poovaiah,1986).

Calcium (Ca2+) has been extensively reviewed as both an essential element and its potential role in

maintaining postharvest quality of fruit and vegetable crops (Kirkby & Pilbeam, 1984; Bangarth, 1979) by contributing to the linkages between pectic substances within the cell-wall (Demarty et al., 1984). The presence of Ca2

+ ions increases the cohesion of cell-walls (Demarty et al., 1984). It is also involved in reducing the rate of senescence and fruit ripening (Ferguson, 1984). A 1% solution of CaCl2 delayed fruit ripening, improved resistance to fungal attack and maintained structural integrity of cell walls of strawberry during a 10 day storage period at 3°C (Lara et al., 2004). Moreover, softening was delayed and storage life was increased by 10–12 weeks in Kiwi fruits stored at 0°C by application of 1% CaCl2 compared with untreated fruit (Dimitrios & Pavlina, 2005). Keeping in view the usefulness of CaCl2 treatments in fruits as revealed by various scientists, the present study was aimed to evaluate the effectiveness of postharvest immersion of different CaCl2

concentrations on the postharvest quality attributes of loquat fruit in refrigerated store.

xxii

Materials and Methods

Fruit of “Surkh” cultivar of loquat were harvested at mature ripe stage from the orchard of Hill Fruit Research Station, Tret, Murree, (73° 17’ 00”E longitude and 33° 50’ 00”N latitude) and transported on the same day to the Post Harvest Laboratory at the Department of Horticulture, Pir Mehr Ali Shah Arid Agriculture University Rawalpindi. The fruit were clipped and washed with distilled water to remove any dirt and dipped for two minutes in the following concentrations of Calcium chloride (CaCl2) solution: i) 0% CaCl2 (control) ii) 1 % CaCl2 solution iii) 2 % CaCl2 solution iv) 3 % CaCl2 solution

Each treatment included one hundred fruits and was replicated three times. Fruit were placed in corrugated soft board cartons in three layers separated by soft board sheets and stored at 4°C in the cold store for 10 weeks. A sample of randomly selected 10 fruits at day one and weekly intervals was collected from each replication in a treatment during the storage period. Data on the following parameters was recorded. Weight loss: To evaluate weight loss, separate samples in 3 replicates of each treatments were used. The same samples were evaluated for weight loss each time at weekly intervals until the end of experiment. Weight loss was determined by the following formula:

Weight loss (%) = [(A−B)/A] x 100 where A indicates the fruit weight at the time of harvest and B indicates the fruit weight after storage intervals.

Fruit firmness: Fruit firmness was determined by peeling the fruit at two equatorial sites and

measuring firmness by means of a Wagner® Fruit Firmness Tester, model FT-327, equipped

with an 8mm plunger tip, using 10 fruits from each treatment. Values were expressed in

ilogram force (kgf).

Total soluble solid: Total soluble solids (TSS) were measured by the method described by Dong et al., (2001). One wedge shaped slice of uniform size from ten fruits per replication in all treatments were juiced together for a composite sample. Thirty fruits were used for each treatment. TSS in Brix% was measured by a hand refractometer (Abbe® model 10450).

xxiii

Titratable acidity: Loquat pulp (10g) was homogenized in 40 ml distilled water and filtered

to extract the juice. Two to five drops of phenolphthalein was added in this juice. A 10 ml

aliquot was taken in a titration flask and titrated against 0.1N NaOH till permanent light pink

color appeared. Three consecutive readings were taken from each replication of a treatment

and percent acidity as malic acid was calculated by using the following formula:

(ml NaOH used) (Normality of NaOH) (Equivalent wt. of

malic acid) %TA =

(wt. of sample) (vol. of aliquot taken)

Ascorbic acid content (Vitamin C): Ascorbic acid was determined by the method described

by Hans (1992). Loquat pulp (5g) from 10 fruits was blended with 5 ml 1.0% Hydrochloric

acid (w/v) and centrifuged at 10,000 rpm for 10 minutes. The absorbance of the supernatant

was measured at 243 nm. For calibration, standard solutions were prepared in the same

manner from 100 µg ml-1 AA solution in 1% HCl. The Ascorbic acid content was calculated

as mg 100g-1 edible portion.

Browning index: Browning index was assessed weekly by measuring the extent of browning area as described by Wang et al., (2005), using 30 fruits on the following scale: 0= no browning; 1=less than ¼ browning; 2= ¼ to ½ browning; 3= ½ to ¾ browning; 4= more than ¾ browning. The browning index was calculated using the following formula:

Browning Index = [(1 x N1 + 2 x N2 + 3 x N3 + 4 x N4) / (4 X N)] x 100 where N = total number of fruits observed and N1, N2, N3 and N4 will be the number of fruits showing the different degrees of browning. Relative electrical conductivity: Relative electrical conductivity was measured by the method described by Fan & Sokorai (2005) with a slight modification. Ten discs of flesh tissue were excised from 10 fruits of each replicate in a treatment by a 10mm diameter stainless steel cork borer and washed in distilled water, dried and put into 100ml conical flasks containing 50ml of distilled water. Initial electrolyte leakage was determined at 1 min (C1) and 60 min (C60) of incubation. The samples were then autoclaved at 121°C for 25 minutes, after cooling the solution was re-adjusted to a volume of 50 ml and total conductivity (CT) was measured. The Relative Electrical Conductivity in percent (REC) was calculated from the following equation:

xxiv

REC (%) = (C60 −C1) / CT ×100. Statistical analysis: The experiment was a completely randomized design (CRD) with factorial arrangement. Comparison between means was evaluated by Duncan's Multiple Range Test at 5% level of significance. All storage treatments were done with three replications. Results and Discussion

Maximum weight loss occurred in control and 1% CaCl2 while lowest loss (2.57%) was recorded in 3% CaCl2 (Table 1). Weight loss was highest during the sixth and eighth weeks. Overall highest weight loss occurred in control during the sixth week (Fig. 1). Calcium applications have known to be effective in terms of membrane functionality and integrity maintenance which may be the reason for the lower weight loss found in Calcium treated fruits (Lester & Grusak, 1999). Mahajan & Dhatt (2004) reported that pear fruit treated with CaCl2 proved to be most effective in reducing weight loss compared to non treated fruit during a 75 days storage period. Thus, calcium might have delayed senescence and reduced the rate of respiration and transpiration. Effect on firmness: Maximum firmness was recorded in 2% & 3% CaCl2 as compared to control and 1% CaCl2. Maximum firmness was recorded in 3% CaCl2 during eight and tenth weeks (Fig. 1). The retention of firmness in calcium treated fruits might be due its accumulation in the cell walls leading to facilitation in the cross linking of the pectic polymers which increases wall strength and cell cohesion (White & Broadly, 2003). These results are also in accordance with those reported by Shuiliang et al., (2002) that postharvest dips with CaCl2 maintained firmness and eating quality of loquat. Effect on total soluble solids: Maximum TSS was observed in 3% CaCl2 (13.1 Brix %) followed by 2% CaCl2. Lowest TSS was recorded in control. Highest TSS in 3% CaCl2 might be due to the fact that more concentration of CaCl2 (3%) formed a thin layer on the surface of fruit which delayed degradation process. The increase in TSS from 2nd week upto 6th week during storage (Fig. 1) was probably due to hydrolysis of polysaccharides and concentrated juice content as a result of dehydration. An initial increase then loss of TSS in loquat has also been reported by (Ding et al., 1998). Effect on titratable acidity: Titratable acidity decreased gradually in all treatments (Fig. 1) and did not seem to be influenced by the postharvest calcium dips. Manganaris et al., (2005) has also reported that postharvest calcium chloride dips did not effect TA % in peaches during four weeks of storage. Titratable acidity is directly related to the concentration of organic acids present in the fruit, which are an important parameter in maintaining the quality of fruits. In loquat malic acid is the principal acid contributing 90% of the total organic acid content Ding et al., (1998). Ball (1997) suggested that acidity decreases due to fermentation or break up of acids to sugars in fruits during respiration. In the present study it seems that Calcium treatments did not have any significant effect on fermentation process which could delay breakup of acids and maintain TA. Effect on ascorbic acid (Vit C) content: All three concentrations of Calcium chloride (CaCl2) were similar in effect compared to control. Treatments of 1% and 2% CaCl2 had an ascorbic acid loss of 10.9% and 8.4% compared to 19% loss in control while in 3% this loss was only 2.5% (Fig. 1). Ascorbic acid level decreased gradually during the ten weeks storage period. Ascorbic acid is an important nutrient quality parameter and is very sensitive to degradation due to its oxidation (Veltman et al., 2000) compared to other nutrients during food processing and storage. These results show that CaCl2 treatments had a significant effect on retaining ascorbic acid content in loquat fruit. This might be because higher concentrations of CaCl2 delayed the rapid oxidation of ascorbic acid. Ruoyi et al., (2005) also stated that AA content of peaches was maintained in a fifty days storage with a postharvest application of 0.5% CaCl2.

Table 1. Effect of calcium chloride on quality attributes of “Surkh” cv. of loquat during ten week storage at 4 º C.

Treatment TA (%)

Firmness (kgf)

TSS (brix %)

Ascorbic acid mg 100g -1 FW

Weight loss(%)

Browning index (%)

REC (%)

Control 0.40a 1.01c 11.41d 2.59b 3.23a 18.72a 51.26a

xxv

CaCl 1% 0.41a 1.11b 12.19c 2.85a 2.98ab 18.15a 48.69b

CaCl 2% 0.38a 1.18a 12.49b 2.93a 2.70bc 15.79b 44.38c

CaCl 3% 0.41a 1.20a 13.10a 3.12a 2.57c 10.58c 43.07c

LSD 0.03 0.05 0.14 0.26 0.29 1.61 2.11 Values for each parameter followed by the same letter within columns are not significantly different at p<0.05 (DMRT)

0

10

20

30

40

50

0 2 4 6 8 10

Brow

ning

Inde

x (%

)

C

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)

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0.2

0.4

0.6

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0 2 4 6 8 10Storage period (w eeks)

Vit C

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0g F

W)

Fig. 1. Effect of calcium chloride agents on quality attributes of “Surkh” cv. of loquat. Vertical bars represent SE of means. LSD for browning index = 2.50, firmness = 0.06, titratable acidity = 0.05, total soluble solids = 0.66, relative electrical conductivity = 5.65, ascorbic acid = 0.32 Effect on browning index (BI): Data in Table 1 reveals significant difference in BI as a result of CaCl2 treatments. Maximum BI (18.72%) was recorded in control while lowest BI (10.58%) was observed in 3% CaCl2. Control and 1% CaCl2 were statistically similar. Overall BI increased during storage (Fig. 1).

Oxidative membrane injury allows the mixing of the normally separated enzyme (PPO) and oxidizable substrates (polyphenols), which lead to browning (Hodges, 2003). High calcium concentrations result in decreased flesh browning symptoms which are directly associated with calcium content in fruits (Hewajulige et al., 2003). Therefore, calcium dips raise the possibility of producing fruit less susceptible to flesh browning symptoms. Rosen & Kader (1989) reported that 1% CaCl2 dip reduced softening and browning rates of ’Bartlett’ pear slices. This study also indicates that CaCl2 treatments had lower BI compared to control. This could be due to the fact that calcium helps to maintain membrane stability as mentioned by Poovaiah (1988) and Picchioni et al., (1995).

xxvi

Effect on relative electrical conductivity (REC): Highest REC (51.26%) was recorded in control (Table 1). Both the higher concentrations of CaCl2 had lower REC values. In control REC raised upto 67.63% at the end of tenth week (Fig. 1). Research in postharvest physiology suggests that Ca may be involved in control of membrane stability and senescence of plant cells (Leshem, 1992; Torre et al., 1999; Rubinstein, 2000). Decreased electrolyte leakage by calcium application increases the cell wall integrity and stability (Mortazavi et al., 2007). In this study, 3% CaCl2 had the lowest REC compared to control. The lower REC might be due to less disruption in the plasma lemma membranes as reported by Meng et al., (2009) and the increased cohesion of cell membranes (Demarty et al., 1984). Conclusion

This study shows that 1% CaCl2 treatment did not show significant effect on quality parameters and was similar to the control, while 2% CaCl2 had higher firmness and REC. Dipping fruit in 3% CaCl2 retained maximum TSS, firmness and reduced RSA, browning index and weight loss up to 4-5 weeks. References Ball, J.A. 1997. Evaluation of two lipid based edible coating for their ability to preserve post harvest quality of green

bell peppers. Master Diss., Faculty of the Virginia Polytecnic Institute and state University. Blacksburg, Virginia, USA.

Bangarth, F. 1979. Calcium-related physiological disorders of plants. Ann. Rev. Phytopathol., 17: 97-122. Demarty, M., C. Morvan and M. Thellier. 1984. Ca and the cell wall. Plant Cell Environ., 7: 441-448. Dimitrios, G. and D.D. Pavlina. 2005. Summer-pruning and preharvest calcium chloride sprays affect storability and

low temperature breakdown incidence in kiwifruit. Postharvest Biology and Technology, 36: 303-308. Ding, C.K., Chachin, Y. Hamauzu, Y. Ueda and Y. Imahori. 1998. Effects of storage temperatures on physiology and

quality of loquat fruit. Postharvest Biology and Technology, 14(3): 309-315. Dong, Li., H.W. Zhou, L. Sonega, A. Lers and S. Lurie. 2001. Ripening of “Red Rosa” plums: effect of ethylene and 1-

methylcyclopropane. Aust. J. Plant. Physiol., 28:1039-1045. Fan, X. and K. J.B. Sokorai. 2005. Assessment of radiation sensitivity of fresh-cut vegetables using electrolyte leakage

measurement. Postharvest Biology and Technology, 36: 191-197. Feng, G., H. Yang and Y. Li. 2005. Kinetics of relative electrical conductivity and correlation with gas composition in

modified atmosphere packaged bayberries (Myrica rubra Siebold and Zuccarini). Food Sci. and Tech., 38(3): 249-254.

Ferguson, I.B. 1984. Calcium in plant senescence and fruit ripening. Plant Cell Environ., 7: 477-489. Glenn, G.M. and B.W. Poovaiah. 1990. Calcium-mediated postharvest changes in texture and cell wall structure and

composition in ‘‘Golden delicious’’ apples. J. Amer. Soc. Hort. Sci., 1: 15 - 19. Hans, Y.S.H. 1992. The guide book of food chemical experiments. Pekin Agricultural University Press, Pekin. Hewajulige, I.G.N., R.S. Wilson-Wijeratnam, R.L.C. Wijesundera and M. Abeysekere. 2003. Fruit calcium

concentration and chilling injury during low temperature storage of pineapple. J. Sci. Food and Agric., 83: 1451-1454.

Hodges, D.M. 2003. Postharvest oxidative stress in horticultural crops. Foods products press. The Howerth press. Binghampton. N.Y.

Holdsworth, S.D. 1988. Conservacion de frutas y hortalizas. Zaragoza: Acribia. 12 pp. Hussain, A., N.A. Abbasi and A. Akhtar. 2007. Fruit characteristics of different loquat genotypes in Pakistan. Proc.

IInd Intl. Sym. On Loquat. Acta Hort., 750: 287-291. Kader, A.A., D. Zargorg and E.L. Kerbel. 1989. Crit. Rev., Food. Sci. Nutr., 28: 1-30. Kirkby. E.A. and D.J. Pilbeaam. 1984. Calcium as a plant nutrient. Plant cell Environ., 7: 397-405. Lara, I., P. García and M. Vendrell. 2004. Modifications in cell wall composition after cold storage of calcium-treated

strawberry (Fragaria × ananassa Duch.) fruit. Postharvest Biology and Technology, 34(3): 331-339. Leshem, Y.Y. 1992. Plant Membrane: A Biophysical Approach to Structure, Development and Senescence. Kluwer

Academic Publisher, Dordrecht. ISBN 0-7923-1353-4. Lester, G.E. and M.A. Grusak. 1999. Postharvest application of calcium and magnesium to honeydew and netted

muskmelons: Effects on tissue ion concentrations, quality and senescence. J. Amer. Soc. Hort. Sci., 124: 545-552. Lester, G.E. and M.A. Grusak. 2004. Field application of chelated calcium: postharvest effects on cantaloupe and

honeydew fruit quality. Hort Technology, 14: 29-38.

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Mahajan, B.V.C. and A.S. Dhatt . 2004. Studies on postharvest calcium chloride application on storage behaviour and quality of Asian pear during cold storage. Intl. J. Food Agri. and Environment, 2(3-4): 157-159.

Manganaris, A., M. Vasilakakis, I. Mignani, G. Diamantidis and K. Tzavella-Klonari. 2005. The effect of preharvest calcium sprays on quality attributes, physicochemical aspects of cell wall components and susceptibility to brown rot of peach fruits (Prunus persica L. cv. Andross). Scientia Horticulturae, 107(1): 4-50.

Meng, X., J. Han, O. Wanga and S. Tian. 2009. Changes in physiology and quality of peach fruits treated by methyl jasmonate under low temperature stress. Food Chemistry, 114: 1028-1035.

Montoya, M.M., J.L. Plaza and V. Lopez-Rodriguez. 1994. Relationship between changes in electrical conductivity and ethylene production in avocado fruits. Lebensmittel-Wissenschaft und-Technologie, 27: 482-486.

Mortazavi, N., R. Naderi, A. Khalighi, M. Babalar and H. Allizadeh. 2007. The effect of cytokinin and calcium on cut flower quality in rose (Rosa hybrida L.) cv. Illona. J. Food, Agric. Environ., 5(3-4): 311-313.

Ozkan, M., A.E. Kırca and B. Cemero lu. 2004. Effects of hydrogen peroxide on the stability of ascorbic acid during storage in various fruit juices. Food Chemistry, 8(4): 591-597.

Piccioni, G.A., A.E. Watada, W.S. Conway, B.D. Whittaker and C.E. Sams. 1995. Phospholipid, galactolipid and steryl lipid composition of apple fruit cortical tissue following postharvest CaCl2 infiltration. Phytochemistry, 39: 763-769.

Poovaiah, B.W. 1986. Role of Calcium in prolonging storage life of fruits and vegetables. Food Tech., 40: 86-89. Poovaiah, B.W. 1988. Molecular aspects of calcium action in plants. Hortscience, 23: 267-271. Rosen, J.C. and A.A. Kader. 1989. Postharvest physiology and quality maintenance of sliced pear and strawberry

fruits. J. Food Sci., 54: 656-659. Rubinstein, B. 2000. Regulation of cell death in flower petals. Plant Mol. Biol., 44: 303-318. Ruoyi, K., Y. Zhifang and L.Z. Zhaoxin. 2005. Effect of coating and intermittent warming on enzymes, soluble pectin

substances and ascorbic acid of Prunus persica (cv. Zhonghuashoutao) during refrigerated storage. Food Research International, 38: 331-336.

Shuiliang, C., Y. Zhende, L. Laiye, L. MeiXue, S.L.Chen, Z.D. Yang, J.Y. Lai and M.X. Liu. 2002. Studies on freshness keeping technologies of loquat. South China Fruits, 31(5): 28-30.

Torre, S., A. Borochov and A.H. Halevy. 1999. Calcium regulation of senescence in rose petals. Physiol. Plant., 107: 214-219.

Veltman, R.H., R.M. Kho, A.C.R. van Schaik, M.G. Sanders and J. Oosterhaven. 2000. Ascorbic acid and tissue browning in pears (Pyrus communis L. cvs Rocha and Conference) under controlled atmosphere conditions. Postharvest Biology and Technology, 19(2): 129-137.

Wang, Y.S., S.P. Tian and Y. Xu. 2005. Effects of high oxygen concentration on pro- and anti-oxidant enzymes in peach fruits during post harvest periods. Food Chemistry, 91: 99-104.

Watada, A.E. 1987. Vitamins. In: Postharvest physiology of vegetables. (Ed.): J. Weichmann. New York: Dekker, p. 12-19.

White, P.J. and M.R. Broadley. 2003. Calcium in plants. Ann. Bot., 92: 487-511. Xuetong, F. and J.B.S. Kimberly. 2005. Assessment of radiation sensitivity of fresh-cut vegetables using electrolyte

leakage measurement. Postharvest Biology and Technology, 36(2):191-197.

(Received for publication 17 October 2009)

1

Chapter 1

INTRODUCTION

1.1 LOQUAT

The Loquat is botanically known as “Eriobotrya japonica” (Thumb.) Lindl. It is

an evergreen, sub tropical fruit tree of the ‘Rosaceae’ family. The name, Eriobotrya is

derived from the Greek words, “erion” meaning wool and “botrys” meaning cluster

referring to the woolliness present on the fruits and leaves. The word “japonica” refers to

Japan. Loquat fruit resemble apricots in size, the shape varies from round to oblong, with

light yellow to orange colored skin. The flesh color varies from orange to light cream in

color. It is a very juicy and may have one or more seeds. It is usually sweet with a slight

acidic flavor. It competes apples due to its rich sugar, acid and pectin content

(Anonymous, 2006).

1.2. ORIGIN AND DISTRIBUTION

The loquat is believed to be originated in China, and is presently grown

worldwide at moderate altitudes including Japan, Europe, Middle East, Africa, Asia,

Australia, New Zealand and America. In Asia, it has been cultivated for more than 1,000

years. It was introduced in the U.S. in the eighteenth century (Crane and Caldeira, 2006)

1.3 LOQUAT VARIETIES

There are believed to be more than 800 cultivars of loquat grown around the

world. According to T. Ikeda, 46 cultivars are being cultivated in Japan. Loquat cultivars

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are generally classified into "Chinese" or "Japanese" groups. Loquat belonging to the

Chinese group has slender leaves, pear to round shaped fruit with orange skin and flesh.

The fruit is slightly acidic with many seeds. It is harvested in the mid to late season and

has excellent keeping quality.

The Japanese group has broad leaves with pear to oblong fruit. The skin is light

yellow with whitish creamy flesh. It is very juicy with only one or few large seeds. It is

harvested in the early to midseason and has moderate keeping quality (Morton, 1987).

Caballero and Fernandez (2003) described two varietal groups, ‘Local’ and ‘Tanaka’

being cultivated in Pakistan, however, the local group is further classified into two

groups. The one with characters resembling the above mentioned “Chinese” cultivars is

known as “Surkh” and the second with characters resembling the “Japanese” cultivars is

known as “Sufaid”. Both these groups are widely cultivated in the Punjab and NWFP

province. The third exotic group named “Tanaka” introduced in 1965 (Caballero and

Fernandez, 2003) is mainly being cultivated in small pockets of the NWFP province.

Surkh Sufaid

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Loquat is considered one of the favorite fruits in Pakistan and is cultivated in the

North Western Frontier Province (NWFP) and Punjab provinces. (Hussain et al.,

2007). Pakistan can produce good quality loquat for export purpose, still it is mainly

consumed in the local markets (Hussain et al., 2007), mainly because of its delicate

nature and poor handling, transportation and storage facilities. Only a small amount is

exported to Middle Eastern countries mainly Dubai (Khan, 2003). Therefore,

proper handling techniques and storage facilities are vital to promote loquat production in

Pakistan.

1.4 LOQUAT AREA AND PRODUCTION

World loquat fruit production is 549,000 ton, China (453,600 ton) and

Spain (43,300 ton) being the main producers followed by India, Japan and

Pakistan (Lin, 2007). In Pakistan, 1472 hectares of land is under loquat

cultivation which yields 10688 tonnes annually. Punjab and NWFP contribute

98 % of the total produce (GOP, 2007). In Punjab, it is mainly grown at Murree

(Chattar and Tret), Rawalpindi (Taxila, Wah and Hasan Abdal) and Chakwal

(Kalar Kahar and Choa Saiden Shah), while in NWFP it is cultivated in Mardan

region, Peshawar and Hari Pur (Hussain et al., 2007).

1.5 NUTRITIONAL AND MEDICINAL IMPORTANCE OF LOQUAT

Loquat is rich in vitamins A, B, C, phosphorus, calcium, mineral salts and sugars

(Karadeniz, 2003). Nutritionally it contains sucrose, malic acid and small amounts of

4

citric, succinic and tartaric acid. Loquat with higher total sugar contents (above 10%) are

preferred by most consumers (Morton, 1987). Loquat is rich in carotenoids, including

provitamin A. The fruit, kernel and tender leaves are all used for medicinal purpose. The

leaves and kernels contain amygdalin, which is known as anti–cancer vitamin (Tierra,

2005).

Leaves and fruits of loquats have traditionally been considered to have high

medicinal value (Duke and Ayensu, 1985; Wee and Hsuan, 1992). Its leaves are known

to have many physiological actions such as anti-inflammatory, antitussive expectorant

(Hamada et al., 2004) and are used to cure dermatosis, relieve pain (Nishioka et al.,

2002; Sakuramata et al., 2004).

1.6 ECONOMIC VALUE

Loquat flowers during autumn, fruit grows during winter and ripens in the

spring (Cuevas et al., 2007). Loquat fruit becomes available during the months

of April/May in Pakistan, when no other fresh fruit is available in the market,

filling a gap in the market between oranges and the first stone fruits of the

season. Since it is the first fruit of the year, it sells at a premium price (Khan, 2003).

Loquat flowers in autumn, making it a good source of nectar for honey bees (Marino and

Nogueras, 2003).

Loquat is commercially an important fruit crop in Pakistan but little importance

has been given to this fruit for its promotion, mainly due to its perishable nature and short

storage life. Post harvest losses of horticultural commodities are estimated to be around

17-40% (Rind, 2003). Postharvest losses in fruits and vegetables start immediately after

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harvest and deteriorate the quality of the produce. The major factors for post-harvest

losses are inadequate pre-harvest practices such as production techniques, improper

fertilizer, pest and disease management, harvesting at improper stage and post-harvest

problems such as inadequate field heat removal, proper sanitary measures, poor

packaging without grading, improper transportation, storage and marketing strategies

(Kader, 2002a). To increase their post harvest life, it is important to understand different

physiological aspects related to ripening and senescence.

Postharvest treatments require properly sanitized equipment, controlling

temperature, humidity and gas exchange (ethylene, O2 and CO2) during transportation

and storage. The proper use of these practices can extend the postharvest shelflife of the

produce (Armitage and Laushman, 2003; Young, 2002; Schoellhorn et al., 2003).

Bruising and mechanical injury are general causes in increasing the postharvest

losses and deteriorating the quality fruits and vegatables (Cappellini and Ceponis, 1984).

Fully-ripe loquat is very perishable, sensitive to physical damage and require very careful

handling. Loquat contains high concentrations of phenolics and high polyphenol oxidase

activity. The fruit tissue turns brown after any mechanical injury because of oxidation of

the phenolic compounds (Ding et al., 2002). During the process of oxidation, free

radicals like O2-, OH-, H2O2 etc. are also produced which can result in membrane leakage

and ultimate death of tissue (Larson, 1988). Enzymes acting as antioxidant such as

superoxidase dismutase (SOD), catalase (CAT), peroxidase (POD), and other compounds

like ascorbic acid, tocopherols (Vit E) etc. play their role in preventing the deteriorative

effects of oxy free radicals (Bartosz, 1997). High levels of these antioxidants in fruits

result in increased shelf life and decrease in browning (Abbasi et al., 1998; Abbasi and

Kushad, 2006) . High levels of antioxidants in nutrition are known to reduce cardiac and

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6

blood pressure problems (Verlangieri et al.,1985; Ascherio et al., 1992) and mortality

due to cancer (Willet, 1994).

Spoilage of fruits occur mainly due to dehydration, high respiration, microbial

infestation and various physiological disorders. To minimize these problems extensive

experiments have been performed to increase the shelf life of fruits and vegetables by the

use different chemicals, coatings and use of modified atmosphere packages (MAP) to

control water loss and undesirable browning affecting the quality of the produce. Plastic

films can reduce weight loss and extend the shelf life of fruits while still allowing other

biological processes to continue (Sardi, 2005). Dipping treatments delay several

physiological disorders and reduce degradation processes that adversely affect quality of

the product. Surface treatments rinse the enzymes and substrates released from the

surfaces of the damaged cells. With increasing awareness among the consumers, more

emphasis has been given to cut down or annihilate the use of synthetic chemicals in

food products. Therefore stress has been given to explore and use natural alternatives as

food additives for controlling spoilage due to micro organisms in food products (Robert

et al., 2003).

In order to understand the metabolic processes in fruits such as ripening,

softening and senescence, knowledge of the changes occurring in fruits after harvest are

of prime importance. These are important not only in determining the best suitable

commercial practices but also to specify the postharvest requirements of fruits. No work

has been reported in Pakistan on the shelf life characteristics and physio-chemical

changes during storage of local loquat cultivars. The present study was aimed to :

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7

1. Investigate the effectiveness of different polyethylene films and naturally

occurring food grade chemicals (ascorbic acid, citric acid and calcium

chloride) to enhance the shelf life of loquat.

2. Study the changes in total antioxidants, enzymes (Superoxide dismutase,

Catalase, Peroxidase, Polypenol oxidase), phenolics along with other

physiological changes during cold storage as a result of different treatments.

3. Extend the availability of loquat fruit in local and distant markets along with

maintenance of its nutritional level and quality.

This knowledge will be helpful to extend the storage life of loquat fruit for other

researchers and for industry interested in reducing browning and extending shelf life of

loquat.

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8

Chapter 2

EFFECT OF POLYETHYLENE PACKAGES ON KEEPING QUALITY OF LOQUAT

2.1 ABSTRACT

Loquat is a perishable fruit and requires very careful handling. To extend

the shelf life of loquat, the effectiveness of different packaging materials including high

density polyethylene (HDPE) 0.09mm thickness, low density polyethylene (LDPE) 0.03

mm thickness, 0.25% perforated HDPE and LDPE were studied. Two local popular

cultivars of loquat “Surkh” and “Sufaid” (named after their skin and pulp color), were

selected from the orchard of Hill fruit research station, Tret. The fruit were hand picked

at mature ripe stage and transported to the Department of Horticulture, PMAS Arid

Agriculture University, Rawalpindi, in soft board cartons. After washing, the fruit were

sorted and packed in soft board cartons and placed in a cold store at 4˚C. Changes in

total soluble solids, browning index, firmness, ascorbic acid, titratable acidity, electrolyte

leakage, total soluble proteins, polyphenols, polyphenol oxidase, superoxidase dismutase,

peroxidase, catalase and total antioxidants as affected by different treatments were

determined. Non perforated packages had high AA, TA, total, reducing and non

reducing sugars, SOD and CAT activity whereas TSS, POD and weight was lower in

both cultivars for the first six weeks as compared to both perforated polyethylene

packages.

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9

2.2 INTRODUCTION

Fruits and vegetables are generally perishable. If proper packaging and storage is

not done, they will decay rapidly making them unedible. Changes in quality parameters

e.g sugar content, firmness, flavor, and aroma are of greater significance to the consumer

and require proper environmental conditions to retard their deterioration. Quality

improvement of a produce after harvest may not be possible however, reducing the rate

of quality loss can be achieved through adequate postharvest technology. The use of

artificial storage systems provides ideal conditions to the produce and maintains its

desirable quality for the longest possible time (Maria, 2007). Decay and mechanical

damage leading to browning are the prime problems of loquat after harvest due to which

it has a short shelf life (Ding et al., 2002). Postharvest quality is dependent on several

pre and post harvest factors. The use of suitable postharvest storage practices may

affect the senescence process and lengthen the shelf life for extended markets.

Packing of fruits in polyethylene films packages leads to the modification of

atmosphere inside the bag. It reduces the concentration of O2 and increases the

concentration of CO2 until a steady state is reached (Amaros et al., 2008). Such

technique is termed as modified atmosphere packaging (MAP). The object of this study

was to analyze loquat quality evolution during postharvest MAP storage by using

polyethylene (PE) films in order to reach the beneficial effects of MAP and avoid the

detrimental effects on fruit quality caused by excessive high or low CO2 and O2

concentrations.

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2.3 REVIEW OF LITERATURE

Loquat has a short shelf life. After harvesting, it decays very rapidly accompanied

by moisture loss and deterioration in its nutritional quality (Ding et al., 2002). These

problems in loquat can be controlled effectively by the use of several techniques

including the use of modified atmosphere packing (MAP) (Ding et al., 2002). Cold

storage has proved to be useful in maintaining the quality of loquat and increasing its

shelf life, although water loss and the decline of organic acids levels cannot be

completely inhibited (Ding et al., 1998a). Modified atmosphere packaging (MAP) is

useful to maintain fresh fruit quality during post harvest storage (Beaudry, 1999). Sealing

fruits in low permeable polyethylene (PE) bags creates a modified atmosphere (MA) and

is a low-cost alternative to controlled atmosphere storage (Ding et al., 2002). This

technique consists of sealing a certain number of fruits in plastic bags, the concentration

of O2 decreases while the concentration of CO2 inside the bags start to increase until an

equilibrium is reached (Amaros et al., 2008) and depends on the respiration rate of the

commodity’s, the temperature of storage and type of film used, such as thickness and

permeability (Kader et al., 1989). The selection of appropriate film for each commodity

is an essential factor, since very high CO2 concentration and / or low O2 concentration

can induce physiological damage and anaerobic metabolism which adversely affect fruit

quality (Kader, 1997; Salveit, 1997; Beaudry, 2002 and Watkins, 2000).

2.3.1 Loquat Postharvest Handling

The market of loquat is significantly limited due to their short shelf life and

highly perishable nature. Harvest maturity and postharvest storage conditions are

commonly altered to lengthen the shelf life of fruit for extended markets. Time of

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11

harvest, storage temperature and atmospheric conditions are all key factors in postharvest

physiology of fruit (Singleton, 2003). Being a non- climacteric fruit, loquats are

harvested at a mature, ripe stage as they will not naturally ripen off the tree. Harvesting

loquat prematurely will prevent fruit from reaching full ripeness. Harvesting fruit beyond

mature ripe stages will reduce their shelf stability and shorten their fresh market life.

Normally mature ripe loquat perish within 6-9 days under ambient conditions (Tian et al.,

2007). Postharvest storage techniques may biochemically alter fruit tissue, as respiration

rates increase or decrease, affecting the senescence process.

To increase the shelf life of the produce, it is vital to retard certain deteriorative

processes. The shelf life of fruits and vegetables can be extended by lowering their

respiratory metabolism using low-temperature storage or storing them in a high carbon

dioxide atmosphere (Kader, 1997; Soliva and Martin, 2006). Low refrigeration

temperatures of 1-5 °C are usually indispensable for achieving microbiologically stable

products and make the difference between stable and deteriorated products (Lamikanra et

al., 2000). Low oxygen atmospheres also effectively reduces proliferation of aerobic

bacteria (Al-Ati and Hotchkins, 2002; Soliva and Martin, 2006).

Modified atmosphere packing has been successful in the marketing of fresh

produce by working together with low temperatures in order to maintain freshness,

ensure safety and extend shelf-life, however, ways to find inexpensive, rapid and simple

methods to increase the postharvest life of fruits after harvest are still needed to be able

to compete the market.

12

2.3.2 Modified Atmosphere Packaging (MAP)

Low O2 and high CO2 levels reduces respiration, limits ethylene production,

suppress enzymatic reactions, reduce physiological disorders and preserve the quality of

the product. Browning disorder can effectively be controlled by lowering O2 and

increasing CO2 in the storage atmospheres, which are related to tissue senescence and

release of enzymes and substrates causing browning reactions (Day,1994; Robert et al.,

2003) and suppress genes that codify the enzymes associated with maturation

(Larrigaudiere et al., 2001; Sanchez-Mata et al., 2003). Gorny (1997) stated that low O2

atmosphere below 1 kPa were successful in lowering browning in fruits and

vegetables. In order to decrease respiration activities, oxygen levels should be less than

5% (Kader,1997). Extremely low O2 levels (<2%), however, can cause anaerobic

respiration. At this point the tricarboxylic acid cycle (TCA) is blocked. Pyruvic acid is no

longer oxidized, but it is accumulated and is decarboxylated to form CO2 and

acetaldehyde, which is then reduced to ethanol, resulting in production of off-odor, off-

flavor and tissue breakdown (Kader, 1986; Kays, 1991).

The shelflife of many fruits and vegetables has been extended by slowing

ripening using polyethylene packaging. Carbon dioxide and oxygen levels within the

package is altered with time because of respiration and film permeability. This method

is known as modified atmosphere packaging (Geeson et al., 1981). Modified atmospheres

can improve the retention of flavor depending on the commodity (Wills et al., 1982).

MAP reduces O2 levels and increases of CO2 concentrations around the fruit inside the

film thereby maintaining the quality of produce at a specific cold temperature (Sanchez

et al., 2003, Zagory and Kader, 1988). Exama et al. (1993) indicated that at 4 °C most Deleted: 9

13

commercial films have the desired O2 and CO2 permeability for produce with low or

medium respiration rates. Modified atmosphere packaging also lowers water loss and

maintains firmness by developing a humid atmosphere around the fruit (Batu and

Thompson, 1998). MAP is also considered to be an effective method in preventing

microbial and insect contamination (Cliffe and O’Beirne, 2005).

In active MAP, the desirable atmosphere can be achieved by flushing out the air

with a mixture of O2, CO2 and N2 inside the package immediately reaching the steady

state. However, in a passive MAP, the optimal atmosphere is developed by the respiration

process of the commodity together with the permeability of the packaging resulting in

reduced O2 and increased CO2 levels (Jayathunge and Illeperuma, 2005; Durand, 2006).

Since O2 and CO2 permeate through plastic, permeability of the film package is

important in designing a MAP system (Jayathunge and Illaperuma, 2005; Durand, 2006).

Achievement of a desired modified atmosphere is dependent on the selection of a film

with correct permeability which is created when oxygen and carbon dioxide transmission

rates equal the product’s respiration rate (Day, 1993; Rakotonirainy et al., 2001). A film

of excessive gas permeability creates no atmospheric modification. On the other hand, a

film of insufficient permeability will cause quality losses due to anaerobic respiration

(Church and Parsons, 1995) resulting in off-flavors, odors and susceptibility to decay

(Durand, 2006).

The use of modified and controlled atmospheres is considered as a supplementary

to cold storage and its success depends on the variety of the product, its physiological

stage, the atmosphere around the produce, temperature, and the length of storage (Kader,

14

1997). The principal benefit of modified atmosphere storage is that the product stored

maintains its freshness and eating quality much longer compared to stored at the same

temperature in air. Such produce can be marketed at a time when both the quantity of

available product is low, and the quality of the competing product, not stored in

controlled atmosphere, is poor. This marketing strategy can help to recover all the

additional costs of the modified atmosphere storage plus a reasonable profit (Maria,

2007).

2.3.3 Polyethylene Film Packing

Polyethylene films are high-performance materials which are mostly used in

packaging applications. These are widely used for packaging due to their flexibility,

durability and insulation, moreover, they are effective in moisture retention, resistant to

chemicals and good insulators. High density polyethylene (HDPE) is non stretching,

limits gas exchange and acts as a moisture barrier. They are comparatively cheaper than

low density polyethylene (LDPE). HDPE is generally used as a packaging materials

because it does not have sharp corners. Its main drawback is that it cannot be recycled.

On the other hand, LDPE facilitates gas exchange and is more flexible with good clarity

(IQS, 2005). Packaging provides a barrier to gas exchange with the external atmosphere.

The atmosphere provided by this barrier depends on the type of material, the velocity of

the ventilating air around the product. The effect of these barriers to the gas exchange is

cumulative and must be considered when selecting an adequate handling condition for the

product. Fruits packed in low permeable polyethylene (PE) bags develops a modified

atmosphere (MA), as a result, the consumption of respiration substrates mainly organic

acids and sugars are reduced and fruit quality does not deteriorate (Ding et al., 2002).

15

Ding et al. (1998b) states the loquat fruit quality was maintained for 3 to 4 weeks

if stored at 0 °C and 2 weeks at 10 °C. Loquat placed in polyethylene film bags having

0.15% perforations retained their freshness for 30 days when stored at 1°C and 5°C

(Ding et al.,1998a). Zheng et al. (2000a) reported that respiration decreased in loquat

fruit packaged in polyethylene bags of 0.04 mm thickness and containing 90% O2 at 1ºC

for 35 days. Storage of loquat can be extended upto 2 months at 5 °C in 0.02 mm

thickness polyethylene (PE) bags, with optimum quality and lower decay. After one

month storage, the decay incidence at 5 °C, was 8%, 10%, 15% and 20%, in PE-pf, PE-

20, PE-30 and PE-50 bags respectively (Ding et al., 2002). According to Melo and Lima

(2003) highest total sugar and sucrose contents while minimum reduction of fresh fruit

losses of loquat were achieved with polyvinyl chloride (PVC) 0.02mm and 0.03mm

treatments when stored at 3 ± 2ºC and 85 ± 3% RH for fifty days. Kim et al. (2004)

observed that salad savoy retained its freshness and keeping quality for 25 days when

stored at 5°C in 19 cm × 22 cm polyethylene bags of specific oxygen transmission rates.

Paulis (1990) observed a reduced Botrytis index in PVC film due to accumulation of

CO2 (around 10.5%) resulting in superb quality of the stored product. The use of (PE)

liners in MAP to develop high humid conditions and reduced the incidence of rind

blemish disorder in oranges (Ben-Yehoshua et al., 2001).

2.3.4 Antioxidants

Antioxidants are known to cut down the harmful effect of dangerous oxidants by

combining with these molecules and reducing their destructive power. The term

“Antioxidant ” has been defined in several ways by different researchers. According to

Deleted: ¶¶

16

Britton (1995), an effective antioxidant yields harmless products by removing free

radicals or breaks up the chain reactions of free radicals.

Haila (1999) defined antioxidant as any compound which inhibits oxidation based

on scavenging of free radicals. In broader sense, any substance that significantly delays

or prevents oxidation at very low concentrations than the oxidizable substrate (Halliwell

and Gutteridge, 1995). According to Krinsky (1992) biological antioxidants are

“compounds which defend biological systems from the damaging effects of reactions

which may cause undue oxidations”. There are a number oxidizable substrates including

DNA, proteins, lipids and carbohydrates. In addition vitamins E and C, also are

antioxidants and act as synergists due to their recycling mechanisms. The antioxidant

activity is greater of the compounds combined together than the aggregation of individual

antioxidants (Niki, 1987; Haila, 1999). Antioxidants also have the ability to repair the

damage already done within the injured cells.

The potency of the antioxidants is dependent on several factors such as specific

chemical reactivity toward the radical, the site of generation, reactivity of the radicals,

concentration and site of the antioxidant, the degree of stability, end product of

antioxidant-derived radical, and its interactive ability with other antioxidants

(Tsuchihashi et al., 1995).

2.3.5 Free Radical

An atom or group of atoms having one or more unpaired electrons is termed as

‘free radical’ (Halliwell and Gutteridge, 1989; Abbasi et al., 1998). It can be anionic,

17

cationic or neutral. There are two unpaired electrons in the outer orbital of ground-state

O2 (3O2) and much of its reactivity results from its bi-radical properties. However,

although dioxygen is an oxidant, it is relatively non reactive. Step-wise single electron

addition to molecular oxygen generates various more reactive intermediates known as

oxygen free radicals (OFR’s) including superoxide anion free radical (O2- ), the hydroxyl

radical (OH-), lipid (L) and (X) other peroxy radicals (LOO• and XOO•), transitional

metals including copper and iron, ozone and nitric acid (Punchard and Kelly, 1996). An

oxidizing agent, such as O2, effectively absorbs electrons from the oxidized molecule

(Halliwell and Gutteridge, 1995). The term reactive oxygen species (ROS) refers to a

number of free radicals and intermediates of non-radicals, which oxidize the molecular

oxygen. Reactive oxygen species consisit of many radicals such as superoxide (O2-),

hydroxyl (OH-) and derivatives of oxygen which may not have unpaired electrons

including hydrogen peroxide (H2O2), lipid peroxide (LOOH), singlet oxygen, and

hypochlorous acid (HOCl).

Although oxygen is vital for the endurance of aerobic organisms, its in-vivo

activation may yield toxic forms such as superoxide (O2-) and hydroxyl (OH-) (Fridovich,

1978) and H2O2. The ability of free radicals to donate or remove electrons from the

surrounding molecules indiscriminately may be dangerous for the living organisms

(Abbasi et al., 1998). Free radicals may cause cessation of growth, mutagenesis and cell

death in plants by a direct effect on cellular components or by a secondary effect, which

can be mediated by oxidative breakdown products. Due to their high reactivity, they

readily combine with other molecules such as enzymes, receptors and ion pumps by

Deleted: 8

18

direct oxidation and inactivating or inhibiting their normal function (Punchard and Kelly,

1996).

Apart form OFR’s, carbonyl, thiyl and nitroxyl can also exist as free radical

species. Several other free radicals such as phenolic and aromatic species may form

during the xenobiotic metabolism in conjunction to the natural detoxification metabolism

(Punchard and Kelly, 1996).

2.3.6 Antioxidants In Relation to Shelf Life of Fruits and Vegetables

Oxidation is a fundamental process for the cells in the body. Antioxidants

counteract the damaging effects of oxidation. These are reducing agents which donate

electrons and cause a substance to be reduced. Antioxidants exist in the form of

vitamins, minerals and enzymes. They are a key factor in prevention of several chronic

diseases (Ascherio et al., 1992). Antioxidative processes occur in radical and redox

reactions. ROS and other free radicals cause oxidation that induces deterioration of food,

resulting in rancidity, changes in color, and declines in nutritional quality, flavor, texture

and safety (Antolovich et al., 2001).

In general, the antioxidative system comprises the ROS, substrates such as

proteins, metal-related biomolecules as catalysts, and antioxidants as inhibitors (Hayashi

et al., 2007). The antioxidants are primarily scavengers, reducing the number of free

radicals and helping in the prevention of cellular damage and other disease. Similarly

fruit antioxidants provide resistance to tissues from disease and stress conditions. Many

anti fungal molecules may induce postharvest disease resistance such as phenolic

19

compounds which play a double role by acting as antifungal agents to increase

postharvest life and also as antioxidants to improve the quality during preservation of

food products (Hebert et al., 2002). Antioxidant activity in fruits diminishes as

senescence progresses (Srilaong and Tatsumi, 2003).

With the increasing awareness regarding the benefits of antioxidants in human

health, there has been more emphasis on research in horticulture and food sciences to

study antioxidants in fruits and vegetables and to find out how to improve or maintain

their content and activity during postharvest storage and processing.

Dark green leafy vegetables are rich sources of antioxidants. Dietary antioxidants

comprise of several vitamins including vitamins A, C, and E whereas many non-nutritive

compounds such as polyphenolics, flavonoids, carotenoids, and thiol-containing

compounds also act as antioxidants. Foods which are rich in vitamins A, C, E, and beta-

carotene have more nutritive value. These nutrients are also present in strong colored

fruits and vegetables such as red peppers, spinach, tomatoes, carrots and oranges

(Holetzky, 2005). variouss browning inhibitors also serve as antioxidants (Altunkaya and

Gokmen, 2008).

The other antioxidant compounds in fruits and vegetables include phenolic

compounds, lycopenes, carotenoids, tocopherol and ascorbic acid (Toit et al., 2001; Pyo

et al., 2004). Flavonoids which include multiple functional phenolic groups has 2 to 5

fold stronger radical scavenging capacity than ascorbic acid and tocopherol (Toit et al.,

2001; Kim, 2005).

Deleted: )

20

Apart from above, various antioxidant enzymes are produced in the living cells

such as superoxide dismutase, catalase, and peroxidases which convert the harmful O2-,

OH- and H2O2 to water, and keep down the damage done by oxygen stress (Kaynara et

al., 2005). Glutathione binds with different toxins and acts as a detoxifying agent and

excrete them from the body as waste (Holetzky, 2005). Above all, antioxidants

breakdown the chain of uncontrolled oxidation.

2.3.7 Superoxide Dismutase (SOD)

The Superoxide radical may react with several cellular materials (Hassan and

Scadilios, 1990). It is activated when the electrons are misguided and donated to oxygen.

The electron transport chains in the mitochondria and the photosynthetic apparatus of the

chloroplast are sources of superoxide radicals. Singlet oxygen may be generated during

the transfer of excitation energy from the chlorophyll to oxygen within the chloroplast

(Bowler et al., 1992; Kandhari, 2004).

Superoxide dismutase (EC 1.15.1.1), is the first defensive enzyme against oxygen

derived free radicals and catalyses the dismutation of the superoxide anion (O2- ) into

hydrogen peroxide (H2O2) which is further converted into H2O and O2 by catalase

(Kaynara et al., 2005) and prevents formation of hydroxyl radicals (OH-). This reaction

may be upto 10,000 times quicker than spontaneous dismutation (Bowler et al., 1992).

SOD activity has been linked to physiological stresses such as low temperature, high

intensity light, water stress and oxidative stress (Bowler et al., 1992).The enzyme exists

in aerobic organisms and subcellular compartments which are sensitive to oxidative

stress (Blokhina et al., 2003)

21

Hydroxyl radicals and their derivatives are very reactive (Cadenas, 1989), and

may cause mutation of DNA, denaturing proteins and lipid peroxidation. In the absence

of SOD, O2- is dismutated producing H2O2 and O2 in a pH-dependent reaction. This

dismutation is faster in an acid pH being greatest near pH 4.7 (Sala and Lafuente, 2004).

2O-2 + 2H+ → H2O2 + O2

Hydrogen peroxide is disposed by catalases (E.C.1.11.1.6) and peroxidases (EC

1.11.1.7). The three forms of SOD (Fe-Zn, Mn and Cu) occur in prokaryotic and

eukaryotic organisms (Bannister et al., 1987; Fridovich, 1986). Each form is classified

by their metal cofactor. They are present in living organisms, and are similar in structure.

Each isozymes differs in its sensitivity to H2O2 and KCN (Bannister et al., 1987;

Blokhina et al., 2003). Superoxide and hydrogen peroxide can react in a Haber-Weiss

reaction to form hydroxyl radicals in the presence of metal ions.

SOD and CAT activity in apple has been known to decrease at low temperature

(Gong et al., 2001). Similarly SOD activity in bananas and mangoes decreased with

storage at 12 °C and 6 °C (Kondo et al., 2005), whereas SOD activity of ‘Navelina”

oranges increased during storage at 22 °C under 55-60% relative humidity (Sala and

Lafuente, 2004). SOD activity diminished rapidly after 30 days in peaches stored in

controlled atmosphere conditions (Wang et al., 2005).

22

2.3.8 Catalase (CAT)

Catalase (EC 1.11.1.6) is the most efficient enzyme in both animals and plants

which regulate the concentrations of H2O2. It converts H2O2 into one molecule of H2O

and a half molecule of O2 without generating harmful radicals (Burris, 1960).

2H2O2 2H2O + O2

In plants, catalase is found predominantly in peroxisomes and glyoxysomes, and

acts mainly to dispose off H2O2 formed during photorespiration or oxidation of lipids in

glyoxsomes (Bowler et al., 1992). H2O2 is formed normally as a by-product of

photorespiration, ß-oxidation of fatty acids and the mitochondrial electron transport.

Hydrogen per oxide is generated during the transfer of electrons to molecular oxygen,

which in turn gives rise to the superoxide radical (Montavon et al., 2007). Hydrogen

peroxide is used both as a donor of hydrogen and a substrate by CAT during the catalytic

decomposition of hydrogen peroxide to yield oxygen and water (Burris, 1960).

Hydrogen peroxide and O2 production increase rapidly during stress conditions causing

destruction to cell structures. Catalase removes H2O2 inhibiting the oxidation of phenolic

compounds, on the other hand peroxidase (POD) and polyphenoloxidase (PPO) enhances

their oxidation in the presence of H2O2 and O2 (Montavon et al., 2007).

2.4 MATERIALS AND METHODS

Two local popular cultivars of loquat (Eriobotrya japonica Lindl.) “Surkh” and

“Sufaid” (named after their skin and pulp color), were selected from the orchard of Hill

23

Fruit Research Station, Tret, Murree, located at 73° 17’ 00”E longitude and 33° 50’

00”N latitude. The fruit was hand picked at commercial maturity stage (determined

according to their size and peel colour) in the month of April, sorted, packed in soft

board cartons and transported on the same day to the Post Harvest Laboratory at the

Department of Horticulture, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi.

On arrival, the fruit were clipped from bunches, uniform fruit were sorted, washed with

distilled water to remove any dirt or residuals material and air dried. All immature,

bruised and damaged fruit were discarded. Polyethylene bags (20 x 30 cm) of different

density and perforation as described below were used in this study:

i) High Density Polyethylene (HDPE) bags of 0.09mm thickness

ii) Low Density Polyethylene (LDPE) bags of 0.03mm thickness

iii) HDPE bags (0.09mm) with 0.25% perforation

iv) LDPE bags (0.03mm) with 0.25% perforation

Ten fruits were placed in one PE bag. There were ten bags in each treatment.

Every treatment was replicated three times. All PE bags were sealed, placed in soft board

cartons and stored at 4 °C in the cold storage of the department of Horticulture.

A sample of randomly selected ten fruits at day one and at seven days intervals

was collected from each replication in a treatment during the storage period. A total of

thirty fruit were collected from each treatment. After noting the browning index, the fruit

was hand peeled and cut into small pieces. The composite fruit samples weighing

70 – 80 g was frozen in liquid nitrogen and stored at -20 °C until further analysis.

Deleted: then

24

To analyze variables like TSS, firmness, sugar content, Vitamin C content,

sample portions were separated and used for analysis immediately after sampling. All the

analytical work was conducted in the laboratories of Pir Mehr Ali Shah Arid Agriculture

University, Rawalpindi. Data on the following parameters was recorded to determine the

effect of different treatments in each experiment:

2.4.1 Weight Loss

To evaluate weight loss separate samples in three replicates were kept in similar

conditions as for individual treatment in the cold store. The same fruits were evaluated

for weight loss each time until the end of experiment. Weight loss of fruits was

determined at weekly intervals by the following formula:

Weight loss (%) = [(A−B)/A] x 100

where A was the fruit weight at harvesting time and B, the weight after different

storage intervals.

2.4.2 Fruit Firmness

Fruit firmness was determined by peeling the fruit at two equatorial sites and

measuring firmness by means of a Wagner® Fruit Firmness Tester, model FT-327, fitted

with a 8mm plunger tip, using ten fruit from each treatment. Values were expressed in

kilogram force (kgf).

25

2.4.3 Total Soluble Solid

Total soluble solids (TSS) were measured as stated by Dong et al. (2001). One

wedge shaped slice of uniform size from ten fruits per replication in all treatments were

juiced together for a composite sample. Thirty fruit were used for each treatment. TSS in

Brix% was measured by a hand refractometer (Abbe® model 10450).

2.4.4 Sugars

2.4.4.1 Reducing sugars

Reducing sugars were estimated by the method described by Horwitz (1960). A

10 ml juice sample was taken in 250 ml volumetric flask to which 100 ml distilled water,

25 ml lead acetate solution and 10 ml potassium oxalate were added. Volume was made

up with distilled water and filtered. In a conical flask, 100 ml of Fehling solution was

taken and boiled after adding some distilled water. Sample aliquot was then taken in a

burette and let to run drop wise into the conical flask containing the Fehling solution.

While titrating, slow boiling was continued. On appearance of brick red color 2 – 3 drops

of methyl blue were added and titration continued till again brick red color appeared.

Readings of sample aliquot used were noted and percent reducing sugars were calculated

as below:

Reducing sugars (%) = 6.25 (X / Y)

Where : X = ml of standard sugar solution used against 10 ml Fehling solution

Y = ml of sample aliquot used against 10 ml Fehling solution.

26

2.4.4.2 Total Sugars

Total sugars were estimated by the method described by Horwitz (1960). A 25 ml

of aliquot prepared for reducing sugars was taken in a 100 ml flask to which 20 ml

distilled water and 5 ml of concentrated hydrochloric acid was added for converting the

non-reducing sugars into reducing sugars. For conversion it was kept for 24 hours at

ordinary room temperature for complete hydrolysis and then neutralized with 1N NaOH

solution using phenolphthalein as an indicator and volume made 100ml with distilled

water. Same procedure as for estimating reducing sugars was followed.

Total sugars were estimated by the following formula:

Total Sugars (%) = 25 x (X/Y)

Where: X= ml of standard sugar solution used against 10 ml Fehling solution.

Y = ml of sample aliquot used against 10 ml Fehling solution.

2.4.4.3 Non- Reducing Sugars

Non-reducing sugars were calculated by the following formula.

Non-reducing sugars (%) = Total sugars (%) – [reducing sugars (%) x 0.95]

2.4.5 Titratable Acidity

Loquat pulp (10g) was homogenized in 40 ml distilled water and filtered to

extract the juice. Two to five drops of phenolphthalein was added in this juice. A 10 ml

aliquot was taken in a titration flask and, then titrated against 0.1N NaOH till permanent

27

light pink color appeared. Three readings were recorded from each replication of a

treatment and percent acidity as malic acid was calculated by using the following

formula:

%TA= (ml NaOH used) (Normality of NaOH) (Equivalent wt. of malic acid)

(wt. of sample) (vol. of aliquot taken)

2.4.6 Total Soluble Proteins

Total concentration of protein was measured using method of Bradford (1976)

employing bovine serum albumin as reference. This method is based on the ability of

proteins to bind the dye Coomassie Brilliant Blue G-250. The binding of the dye to

proteins cause a shift in the absorption maximum of the dye from 465 to 595 nm. Protein

reagent was prepared by dissolving 100 mg Coomassie blue in 50 ml ethanol (95%) and

100 ml phosphoric acid (85%), diluted with distilled water to a final volume of 1L. For

measurement of protein concentration in the samples, 100 µl of supernatant was used in

5 ml of Protein reagent. The optical density was recorded at 595 nm against reagent

blank (0.1 ml buffer + 5 ml protein reagent) and expressed as mg protein / g FW.

A standard solution of 1 mg/ml Bovine Serum albumin was prepared and used to

determine the protein concentrations. A standard curve of weight of protein against the

corresponding absorbance was plotted by taking proteins solutions (10 -100 µg) and 5

ml protein reagent. The absorbance was measured at 595 nm after 2 minutes in 3 ml

cuvettes against reagent blank (0.1 ml buffer + 5 ml protein reagent) and expressed as

milligram protein per gram fresh weight of the sampled tissue (mg / g FW).

Deleted: using

Deleted: (commonly know as Bradford dye)

Deleted: by transferring 3 ml of the tube's contents to a 3 ml cuvette

28

2.4.7. Extraction of Enzymes

Extraction and Assay of enzymes was done by the method described by Abassi

et al. (1998) with some modification. Frozen loquat pulp (5g) from ten fruits was

homogenized with a mortar and pestle and suspended in 15 ml of 100 mM KH2PO4

buffer (pH 7.8) containing 0.5% (v/v) Triton X-100 and 1 g polyvinylpolypyrrolidone

(PVPP). The homogenate was centrifuged at 18,000 x g for 30 minutes at 4 °C and

collected supernatant was stored at –20 °C. Three replications were used from each

treatment.

2.4.7.1 Superoxide Dismutase (SOD) Assay

SOD activity was determined following the method of Dhindsa et al. (1981), by

measuring photochemical reduction of nitro blue tetrazolium. Two sets, each of five

cuvettes containing 0, 50, 100, 200, or 300 µl enzyme extract and 13 mM Methionine, 75

µM NBT, 0.1 mM EDTA, 2 µM riboflavin (substrate) were added to each reaction

cuvette. The final volume was made 3 ml by adding 50 mM phosphate buffer (pH 7.8).

One set of reaction cuvettes were kept in dark conditions which served as control. The

other set was placed 50 cm below a light bank consisting of six 40 W fluorescent lamps

for 10 minutes. The absorbance of the illuminated cuvettes was recorded at 560 nm with

their respective non illuminated cuvettes by means of Optima® 3000 plus

spectrophotometer. SOD activity was expressed as SOD units g-1 FW.

29

2.4.7.2 Catalase (CAT) Assay

Catalase activity was assayed according to Abbasi et al. (1998). Two buffer

solutions were used to accomplish the reaction. One solution (Buffer A) consisted of

2.7ml, 15M KPO4 buffer (pH 7.0) while the second solution (Buffer B) consisting of 2.7

ml, 12.5mM H2O2 in 15M KPO4 buffer (pH 7.0). A 300 µl enzyme extract was added to

each of two cuvettes. Both cuvettes were kept in dark. The optical density at 240 nm was

recorded at 45 sec and 60 sec starting from the time the extract was added to the cuvettes,

using a spectrophotometer. The difference in optical density at 45 and 60 seconds

intervals were noted and used to calculate catalase activity. Catalase activity is

expressed as enzyme units g-1 FW.

2.4.7.3 Peroxidase (POD) Assay

POD activity was assayed according to Abassi et al. (1998). The assay mixture

consisted of 2.1 ml, 15 mM NaKPO4 buffer (pH 6.0), 600 µl substrate, which consisted

of 300 µl 1mM H2O2 and 300 µl 0.1 mM guaiacol and 300 µl enzyme extract to a total

volume of 3ml. POD activity was be calculated at 470 nm as a change in optical density

over a 3 minute period and expressed as units g-1 FW.

2.4.8 Ascorbic Acid Content (Vitamin C)

Ascorbic acid was determined by the method described by Hans (1992). Loquat

pulp (5g) from ten fruits of each replication in a treatment was homogenized in 5 ml

1.0% Hydrochloric acid (w/v) and centrifuged at 10,000 x g for 10 minutes. The

absorbance of supernatant was measured at 243 nm. For the calibration the standard

30

solutions were prepared in the same manner from. The Ascorbic acid content was

calculated as mg/100 g edible portion.

2.4.9 Radical Scavenging Activity

Radical scavenging activity measured using a modified version of the Brand-

Williams et al. (1995) method using the free radical 2,2-diphenyl-l-picrylhydrazyl

(DPPH) prepared in a methanol solution. Ground, frozen tissue (5g) was homogenized

and extracted in 10 ml methanol for 2 hours. The extract (0.1 ml) and 3.9 ml of a 6 × 10–

5 mol/L of DPPH solution was incubated for 30 minutes and absorbance (A) at 515 nm

was determined at 0 and 30 min. Radical scavenging activity was calculated as % of

inhibition of DPPH radical by the following formula.

% inhibition = [(AB-AA)/AB] x 100

where: AB —absorption of blank sample (t = 0 min)

AA —absorption of tested extract solution (t = 30 min).

Where N = total number of fruits observed and N1, N2, N3 and N4 will be the

number of fruits showing the different degrees of browning.

2.4.10 Polyphenol Oxidase (PPO) Assay

Polyphenol oxidase (PPO) was determined according to Abassi et al. (1998)

based on the oxidation of catechol. The reaction mixture contained 2.5 ml of 0.1M

sodium citrate buffer (pH 5.0), 0.3 ml of 0.02 M catechol in sodium citrate buffer (pH5.0)

and 0.2 ml enzyme extract in a total volume of 3 ml. The absorbance mixture was

31

recorded at 420 nm by means of a spectrophotometer. PPO activity was calculated as a

change in optical density over a period of 3 minute period. PPO was expressed as ∆OD

min-1 g-1 protein.

2.4.11 Total Phenolic Content

Total Phenolic contents in the juice was determined with Folin-Ciocalteu reagent

(Slinkard and Singleton, 1977) according to the method of Piga et al. (2003), with some

modifications.Homogenised five gram fruit pulp was centrifuged at 4000 x g for 15 min

and filtered. One milliliter sample, 5 ml of Folin-Ciocalteu reagent, 10 ml of a 7 %

Na2CO3 solution and water was added. After one hour, the absorbance was read at

760 nm against the reagent blank. The standard curve for total phenolics was made using

chlorogenic acid standard solution (0-100 mg/L) under the same procedure as above.

All samples were analyzed in three replications. Total phenolics were expressed as

milligrams of chlorogenic acid equivalents (CAE) per 100 g of dry matter and was

calculated by the following formula:

C = c . V / m

where: C—total content of phenolic compounds, mg/g plant extract, in CAE

c—the concentration of chlorogenic acid established from the calibration curve, mg/ml

V—the volume of extract (ml)

m—the weight of fruit pulp (g).

32

2.4.12 Browning Index

Browning index was assessed weekly according to the method described by

Wang et al. (2005) by measuring the browning area on each fruit. A total of 30 fruits

from each treatment were used and browning index noted according to the following

scale: 0= no browning; 1=less than ¼ browning; 2= ¼ to ½ browning; 3= ½ to ¾

browning; 4= more than ¾ browning. The browning index was calculated using the

following formula:

Browning Index = [( 1 x N1 + 2 x N2 + 3 x N3 + 4 x N4 ) / (4 X N)] x 100

2.4.13 Relative Electrical Conductivity

Relative electrical conductivity was measured by the method described by Fan

and Sokorai (2005) with a slight modification. Ten discs of flesh tissue were excised

from ten fruits of each replicate in a treatment by a 10mm diameter stainless steel cork

borer. Each treatment provided 3 x 10 discs. The disks were washed, dried and put into

100ml flasks containing 50ml of distilled water. Initial electrolyte leakage was

determined using a Orion 420A+ (Thermo Electron Corp., USA) at 1 min (C1) and 60

min (C60) of incubation. The samples were then autoclaved at 121 °C for 25 minutes.

The solution was then cooled and re-adjusted to a volume of 50 ml. The total

conductivity (CT) of bathing solution was then measured. The Relative Electrical

Conductivity in percent (REC) was calculated from the following equation:

REC (%) = (C60 −C1)/CT ×100.

33

2.5 STATISTICAL ANALYSIS.

The experiment was a completely randomized design (CRD) with factorial

arrangement. Data obtained was subjected to ANOVA for the validity of statistical

analysis and the means were separated using Duncan's multiple range test (Steel et al.,

1997), utilizing MSTAT-C software (Michigan State University, 1991). A probability (P)

of less than 0.05 was considered to be significantly different. Pearson’s correlation

coefficients between variables were determined using Microsoft Excel package (Office-

2003). All storage treatments were done with three replications, and the experiment was

carried out over two years.

Deleted: MSTAT-C software (Michigan State University, 1991)was used adopting CRD-factorial and Duncan's multiple range was tested at 5% level of significance

34

2.6 RESULTS AND DISCUSSION

2.6.1 Effect on Weight Loss

Treatment means of “Surkh” cultivar of loquat (Table 1.1) reveal significantly

high weight loss in control while high density polyethylene (HDPE) retained maximum

weight after the end of ten weeks storage during both years. Both polyethylene treatments

with perforations had more weight losses as compared to non perforated treatments. Data

on weight loss during different intervals show that weight loss increased during each

interval till the sixth week and then started to decline till the end of tenth week. Storage

period means show that weight loss was highest during the sixth week. Significantly

higher weight loss occured in control (4.35% and 3.78%) during the sixth week each year

(Fig. 1). This was followed by both perforated packages which had the same trend in

weight loss.

In “Sufaid” cultivar, the trend in weight loss among different treatments was

similar to Surkh cultivar (Table 1.2). Highest weight loss was recorded in control while

lowest loss was recorded in HDPE during both years. Non perforated packages had lesser

losses compared to perforated packages during both years. Maximum weight losses

occurred during the fourth and sixth weeks during both years after which it started to

decrease. (Fig. 1). Highest losses were recorded during the first six weeks in control

during both years.

Formatted

Deleted: Appendix

Deleted: Appendix

35

A

0

2

4

6

0 2 4 6 8 10

Wei

ght L

oss

(%)

C

0

2

4

6

0 2 4 6 8 10

B

0

2

4

6

0 2 4 6 8 10

Storage period (w eeks)

Wei

ght L

oss

(%)

D

0

2

4

6


Control

HDPE

HDPEP

LDPE

LDPEP

Fig. 1: Effect of polyethylene packaging on weight loss in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.60, B = 0.64, C = 1.0, D = 1.22

HDPE = High density polyethylene HDPEP = High density polyethylene perforated LDPE = Low density polyethylene LDPEP = Low density polyethylene perforated

36

Table 1.1: Effect of polyethylene packing on weight loss percentage of “Surkh” loquat

Storage period –weeks (W) Treatment (T) 0 2 4 6 8 10 Means*

Control 0.00i 3.43b 3.64db 4.35a 2.18c 1.18de 2.43A HDPE 0.00i 0.05hi 0.19ghi 0.30f-i 0.24ghi 0.28f-i 0.17E HDPEP 0.00i 0.75d-h 0.66d-i 0.72d-i 0.65d-i 0.44f-i 0.54C LDPE 0.00i 0.11hi 0.26f-i 0.21ghi 0.47e-i 0.59d-i 0.27D LDPEP 0.00i 0.48e-i 0.91d-g 1.2d 0.98def 0.23ghi 0.63B Mean** 0.00D 0.97B 1.13AB 1.35A 0.90B 0.54C

Surkh (Year 1)

LSD T=0.07 W=0.26 TW=0.60


Control 0.00g 3.68a 3.56a 3.78a 2.10ba 0.88def 2.33A HDPE 0.00g 0.03g 0.22fg 0.31fg 0.23fg 0.24fg 0.17D HDPEP 0.00g 0.76d-g 0.71d-g 1.33cde 0.76d-g 0.59efg 0.69BC LDPE 0.00g 0.27fg 0.36fg 0.31fg 0.64efg 0.76d-g 0.39CD LDPEP 0.00g 0.45fg 0.94def 1.89bc 1.3cd 0.29fg 0.82B Mean** 0.00D 1.04B 1.16B 1.52A 1.02B 0.55C

Surkh (Year 2)

LSD T=0.32 W=0.728 TW=0.64 Table 1.2: Effect of polyethylene packing on weight loss percentage of “Sufaid” loquat


Control 0.00f 2.64b 3.47a 3.64a 1.49c 0.59def 1.97A HDPE 0.00f 0.14c 0.07f 0.07f 0.09f 0.05f 0.07D HDPEP 0.00f 0.32ef 0.48ef 0.33ef 0.27ef 0.16ef 0.26C LDPE 0.00f 0.13f 019ef 0.21ef 0.41def 0.56def 0.25C LDPEP 0.00f 0.63def 1.00cd 0.80de 0.56def 0.36ef 0.56B Mean** 0.00E 0.77BC 1.04A 1.01AB 0.56CD 0.34D

Sufaid (Year 1)

LSD T=0.11 W=0.23 TW=1.00


Control 0.00k 3.02a 3.14a 3.35a 1.51b 0.35f-k 1.94A HDPE 0.00k 1.13h-k 0.05jk 0.10ijk 0.08ijk 0.10ijk 0.08D HDPEP 0.00k 0.52e-j 0.58e-h 0.55e-i 0.29f-k 0.34f-k 0.38C LDPE 0.00k 01.4h-k 0.31f-k 0.21g-k 0.64d-g 0.73def 0.34C LDPEP 0.00k 0.72def 1.25bc 1.04cd 0.84cde 0.66d-g 0.75B Mean** 0.00C 3.13B 4.13A 3.68AB 3.21B 3.02B

Sufaid (Year 2)

LSD T=0.20 W=0.61 TW=1.22 HDPE= High density polyethylene HDPEP= High density polyethylene (perforated) LDPE= Low density polyethylene LDPEP= Low density polyethylene (perforated) *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)

37

Weight loss is reported to be the most important physiological disorder in

reducing the shelf life of loquat (Amaros et al., 2008). Modified atmosphere packaging

(MAP) have been known to reduce weight losses in loquat (Ding et al. 1998a., Ding et

al., 2002., Amaros et al., 2008) mainly by maintaining high moisture levels inside the

packages thus preventing weight loss. Ding et al. (2002) reported that non perforated

polyethylene (PE) bags reduced weight loss more effectively as compared to perforated

PE bags in loquat during a sixty day storage period. Chen et al. (2003) observed that

MAP using perforated LDPE and non perforated LDPE effectively reduced weight of

loquat as compared to control. According to Nerya et al. (2003) weight loss in HDPE

packed loquat fruits was less as compared to non packed during a three week storage

period at 4°C. Similar results in peaches and nectarines stored in MAP have been

reported by Akbudak and Eris (2004). Results of this study also show that weight loss

was less in all PE treatments as compared to control. Greater weight loss in control might

be due to rapid moisture loss, whereas lower weight loss in different packages might be

due to retention of moisture by the PE packages which conform the results of the work

reported above.

2.6.2 Effect on Firmness

Firmness attributes in loquat fruit of “Surkh” cultivar resulting from different

polyethylene packaging materials is shown in Fig. 2. All packages, except HDPE had

38

A

0

1

2

0 2 4 6 8 10

Firm

ness

(kg/

cm2)

C

0

1

2

0 2 4 6 8 10

B

0

1

2

0 2 4 6 8 10


Firm

ness

(kg/

cm2)

ControlHDPEHDPEPLDPELDPEP

D

0

1

2


Fig 2: Effect of Polyethylene packing on firmness in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.06, B = 0.22, C = 0.05, D = 0.07


Deleted:

A

0

1

2

0 2

Firm

ness

(kgf

)

39

Table 2.1: Effect of polyethylene packing on firmness of “Surkh” loquat


Control 0.66i 0.70i 1.06gh 1.33a-d 1.40abc 1.1fgh 1.04CD HDPE 0.66i 0.50j 1.06gh 1.30a-e 1.06gh 1.43ab 1.00D HDPEP 0.66i 0.80i 1.13e-h 1.13e-h 1.4abc 1.46a 1.10BC LDPE 0.66i 0.96h 1.26b-f 1.36ab 1.26-f 1.26-f 1.13B LDPEP 0.66i 1.16d-g 1.43ab 1.36ab 1.23c-f 1.43ab 1.21A Mean** 0.66D 0.82C 1.19B 1.30A 1.27A 1.34A

Surkh (Year1)

LSD T=0.06 W=0.14 TW=0.06

Storage period –weeks (W) Treatment

(T) 0 2 4 6 8 10 Means* Control 0.73ef 0.76ef 1.36ab 1.33ab 1.46a 1.26abc 1.15AB HDPE 0.73ef 0.60f 1.16bc 1.33ab 1.23abc 1.46a 1.08B HDPEP 0.73ef 0.90de 1.20abc 1.23abc 1.40ab 1.46a 1.15AB LDPE 0.73ef 1.03cd 1.33ab 1.36ab 1.33ab 1.36ab 1.19A LDPEP 0.73ef 1.26abc 1.40ab 1.36ab 1.26abc 1.33ab 1.22A Mean** 0.73C 0.91B 1.29A 1.32A 1.34A 1.38A

Surkh (Year 2)

LSD T=0.08 W=0.09 TW=0.22

Table 2.2: Effect of polyethylene packing on firmness of “Sufaid” loquat


Control 0.76i 0.76i 1.06efg 1.16def 1.13ef 0.96gh 0.97C HDPE 0.76i 0.43j 1.03fg 0.96gh 1.13ef 1.30bcd 0.93C HDPEP 0.76i 0.86hi 1.20cde 1.30bcd 1.43ab 1.43ab 1.16B LDPE 0.76i 1.20cde 1.33abc 1.46a 1.46a 1.46a 1.28A LDPEP 0.76i 1.03fg 1.16def 1.36ab 1.30bcd 1.16def 1.13B Mean** 0.76D 0.86C 1.16B 1.25A 1.29A 1.26A

Sufaid (Year 1)

LSD T=0.06 W=0.12 TW=0.05


(T) 0 2 4 6 8 10 Means* Control 0.83i 0.80i 1.10fgh 1.20d-g 1.06fgh 1.03gh 1.00C HDPE 0.83i 0.50j 1.06fgh 1.13fg 1.23c-g 1.36a-d 1.02C HDPEP 0.83i 0.93hi 1.26c-f 1.40abc 1.46ab 1.53a 1.23B LDPE 0.83i 1.26c-f 1.46ab 1.56a 1.56a 1.53a 1.37A LDPEP 0.83i 1.03gh 1.16efg 1.40abc 1.33b-e 1.20d-g 1.16B Mean** 0.83C 0.96C 1.21B 1.34A 1.33A 1.33A

Sufaid (Year 2)

LSD T=0.09 W=0.17 TW=0.07

HDPE= High density polyethylene HDPEP= High density polyethylene (perforated) LDPE= Low density polyethylene LDPEP= Low density polyethylene (perforated) *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)

40

high firmness values during both years. LDPEP retained maximum firmness (1.21kgf)

during the first year (Table 2.1). During the second year, no significant difference was

observed in control, HDPEP, LDPE and LDPEP (P = 0.05). Storage period means show

that firmness decreased significantly during the first four weeks after which no

significant difference was observed till the end of storage during both years. Firmness in

LDPEP increased significantly from the fourth week, while maximum firmness (1.46

kgf) was attained in HDPEP during the tenth week.

In the “Sufaid” cv. LDPE had significantly higher firmness values (1.28 and

1.37 kgf) during both years (Table 2.2). No significant difference was found in control

and HDPE which had the lowest value during both years, while both perforated packages

were statistically similar during both years. Firmness increased gradually during both

years, reaching its maximum in the sixth week after which no significant increase was

recorded till the end of the storage period (Fig. 2). LDPE had highest firmness from sixth

week onward showing no increase thereafter during both the years.

Changes in loquat fruit firmness during storage is a controversial issue (Amaros et

al., 2008), because of different results obtained depending on the storage conditions and

cultivar used. This study shows that firmness increased during storage. Among different

type of polyethylene packages used, maximum firmness was recorded in LDPE and

LDPEP,whereas lower firmness in HDPE might be due greater retention of moisture.

These results are in accordance with those of Cai et al. (2006c) who reported that fruit

firmness of loquat increased during storage and attributed it to be due tissue

Deleted: Appendix

Deleted: Appendix

41

lignifications. Chen et al. (2003) also recommended LDPEP for storage of loquat as it

maintained the quality attributes during storage.

2.6.3 Effect on Total Soluble Solids

TSS in “Surkh” cultivar (Table 3.1) increased significantly in control during

both years as compared to day one during the ten week storage period. In all other

treatments, TSS decreased gradually. LDPEP had the next higher TSS value after control

during both years (Fig. 3). Lowest value during the first year was recorded in HDPE

while during the second year all PE packages except LDPEP were statistically similar.

The storage period means show an overall decrease in TSS value during the entire

storage period, on the contrary an increasing trend in TSS was observed in control

throughout the storage period. Maximum TSS was recorded in control during the tenth

week while maximum losses occured in the tenth week in HDPE and HDPEP during both

years.

TSS in control of “Sufaid” cultivar also increased as compared to day one during

both years (Table 3.2). Maximum loss in TSS was recorded in HDPE during both years.

LDPEP retained maximum TSS (12.1 ○Brix and 12.3 ○Brix) after control and rest of the

PE packages during both years. Overall, TSS decreased during the storage period and

the trend was almost similar both years. Highest TSS was recorded in control in the

eighth and tenth weeks during both years.

Soluble solids content is one of the most reliable parameters in judging fruit

quality. Quality factors such as TSS, TA and visible quality (e.g. color, size and

Deleted: Appendix

Deleted: Appendix

42

A

8

12

16

0 2 4 6 8 10

TSS

( Brix

)

C

8

12

16

0 2 4 6 8 10

B

8

12

16


TSS

(Brix

)

D

8

12

16

0 2 4 6 8 10

Storage period (weeks)

ControlHDPEHDPEPLDPELDPEP

Fig. 3: Effect of polyethylene packaging on total soluble solids in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.50, B = 0.63, C = 0.46, D = 0.55


43

Table 3.1: Effect of polyethylene packing on total soluble solids of “Surkh” loquat


Control 12.07de 12.9c 13.5b 13.6b 13.8b 14.9a 13.4A HDPE 12.07de 11.43fg 9.8kl 10.2ijk 10.4ij 9.4l 10.5E HDPEP 12.07de 10.7hi 11.8ef 11.5efg 10.1jk 9.8kl 11.0D LDPE 12.07de 12.5cd 11.7efg 10.4ijk 11.6efg 10.2ijk 11.4C LDPEP 12.07de 11.9def 11.7efg 11.6efg 11.3fg 11.2gh 11.6B Mean** 12.07A 11.91AB 11.75B 11.49C 11.47C 11.14D

Surkh (Year 1)

LSD T=0.16 W=0.22 TW=0.50


(T) 0 2 4 6 8 10 Means* Control 12.8def 13.1cd 13.7bc 13.9b 14.7a 15.2a 13.93A HDPE 12.8def 11.9g-k 11.6ijk 10.9l-o 10.7nop 10.0pq 11.34C HDPEP 12.8def 11.4jklm 11.8hijk 11.5jkl 10.6nop 9.9q 11.37C LDPE 12.8def 11.5jkl 11.4jklm 11.2k-n 10.7m-p 10.7m-p 11.39C LDPEP 12.8def 12.1f-j 12.5defg 12.3e-i 12.9de 12.5d-h 12.56B Mean** 12.87A 12.03B 12.23B 11.97B 11.95B 11.64C

Surkh (Year 2)

LSD T=0.25 W=0.28 TW=0.63

Table 3.2: Effect of polyethylene packing on total soluble solids of “Sufaid” loquat


Control 12.83d 13.3c 13.6c 14.1b 14.7a 14.5ab 13.8A HDPE 12.83d 10.5lm 12.1ef 11.2hij 10.6klm 9.6n 11.1E HDPEP 12.83d 12.2e 11.3ghi 11.6fgh 11.0ijkl 11.7jklm 11.6C LDPE 12.83d 11.7fgh 11.8efg 10.4m 10.7jklm 11.1hijk 11.4D LDPEP 12.83d 11.6fgh 13.4c 11.3ghi 12.1ef 11.3ghi 12.1B Mean** 12.83A 11.90C 12.47B 11.77C 11.87C 11.48D

Sufaid (Year 1)

LSD T=0.16 W=0.20 TW=0.46


Control 12.9de 13.5cd 13.7c 14.4b 15.0a 15.5a 14.13A HDPE 12.9de 11.6g-k 11.6g-k 11.5g-k 10.6m 9.2n 11.28D HDPEP 12.9de 11.7ghij 11.9ghi 10.7lm 11.2ijkl 11.1jklm 11.64C LDPE 12.9de 12.1fg 11.4hijk 11.3h-l 11.0klm 10.6m 11.59C LDPEP 12.9de 12.7e 11.8ghi 11.9gh 12.1fg 12.5ef 12.36B Mean** 12.97A 12.35B 12.12BC 11.99C 12.02C 11.75D

Sufaid (Year 2)

LSD T=0.16 W=0.24 TW=0.55


44

firmness) are prime considerations of consumers (Hoehn et al., 2003; Lu, 2004).

Although TSS is known to increase during storage when insoluble starch is transformed

into soluble solids, several studies have shown a decrease in TSS during storage

(Martisen and Schaare, 1998; McGlone and Kawano, 1998; Vela et al., 2003). Numerous

studies have reported that low O2 storage suppresses TSS increase (Hoehn et al., 2003;

Lopez et al., 2002).

Airtight polyethylene bags have been known to reduce water loss and hydrolysis

of polysaccharides which results in less increase in TSS. The changes in TSS are directly

correlated with hydrolytic changes in the starch concentration during the post harvest

period. These changes result in the conversion of starch to sugars, which is an important

index of ripening process (Kays, 1991). In this study increased TSS in control may be

due to the concentration effect because of higher water loss and higher respiration rates

resulting in accumulation of different solutes in cell vacuoles, while decrease in TSS in

PE treatments may be because these treatments retarded the respiration and conversions

of polysaccharides into disaccharides and monosaccharides. These results are similar to

those reported by Munoz et al. (2006) who reported that the soluble solids content

decreased under cold storage as a result of respiration in strawberries.

The results of this study show consistent changes occurring in the loquat fruit as

it progresses towards senescence after harvest. Due to its short life, the fruit

deteriorates very quickly. The major changes include increased firmness, decline in

ethylene production, loss of acidity, and an initial increase followed by a decrease in

TSS. These changes are similar to those found in other varieties (Ding et al., 1998a; Lin

Formatted: Subscript

45

et al., 1999; Zheng et al., 2000b). Pervez et al. (1992) has also stated that polyethylene

wrapping helped in least increase in TSS in guava fruit packaged in non perforated PE

bags at room temperature for 24 days. Similar results were observed by Attia (1995) who

reported a minimum increase in TSS in oranges packaged in perforated bags and stored

for 84 days at 5 °C.

2.6.4 Effect on Sugars

2.6.4.1 Total sugars

HDPE maintained highest total sugars in “Surkh” cultivar (Table 4.1) and

differed significantly from control and rest of the treatments by having the lowest losses

of 5.2% and 4.2% during both years whereas control had 14.6% and 14.2% losses during

both years at the end of ten week storage (Fig 4). In Sufaid cultivar (Table 4.2), HDPE

maintained highest total sugars during both years, with only 5.6% and 7.2% losses

compared to 23.1% and 23.4% losses in control. HDPEP, LDPE and LDPEP had no

significant difference during both years. LDPEP was also statistically at par with control.

Total sugars decreased in all treatments of both varieties during both years of study.


The effect of MAP on reducing sugars of “Surkh” loquat (Table 5.1) show that

HDPE retained highest levels of reducing sugars during both years of study with only

7.4% and 7.5% losses occurring during both years as compared to day one, whereas in

control these losses were 13.4% and 14.6% respectively. The highest losses 15.4% and

Deleted: Appendix

Deleted: Appendix

Deleted: Appendix

46

A

2

4

6

8

10

0 2 4 6 8 10

Tota

l Sug

ars

(%)

C

2

4

6

8

10

0 2 4 6 8 10

B

2

4

6

8

10


Tota

l Sug

ars

(%)

D

2

4

6

8

10


Contro;l HDPE HDPEP LDPE LDPEP

Fig. 4: Effect of polyethylene packaging on total sugars in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.32, B = 0.32, C = 0.37, D = 0.35


47

Table 4.1: Effect of polyethylene packing on total sugars of “Surkh” loquat


Control 8.51a 8.21abc 7.96bcd 7.24g 6.44i 5.25l 7.27B HDPE 8.51a 8.22abc 8.24abc 8.13abc 7.89cde 7.44fg 8.07A HDPEP 8.51a 8.16abc 7.60ef 7.17gh 6.31ij 6.07jk 7.30B LDPE 8.51a 8.29ab 7.61def 6.87h 5.87k 6.24ij 7.23B LDPEP 8.51a 8.25abc 7.93b-e 7.21gh 6.19ijk 5.24l 7.22B Mean** 8.51A 8.23B 7.87C 7.32D 6.54E 6.05F

Surkh (Year 1)

LSD T=0.52 W=0.14 TW=0.32


(T) 0 2 4 6 8 10 Means* Control 8.67abc 8.41bcd 8.31cde 7.19g 6.53h 5.56j 7.44B HDPE 8.67abc 8.83a 8.43bcd 8.18de 7.99ef 7.78f 8.31A HDPEP 8.67abc 8.38bcd 8.17de 7.28g 6.71h 6.16i 7.56B LDPE 8.67abc 8.58abc 8.12def 7.12g 6.79h 6.04i 7.55B LDPEP 8.67abc 8.74ab 8.20de 7.43g 6.77h 5.86ij 7.61B Mean** 8.67A 8.59A 8.25B 7.44C 6.96D 6.28E

Surkh (Year 2)

LSD T=0.39 W=0.14 TW=0.32

Table 4.2: Effect of polyethylene packing on total sugars of “Sufaid” loquat


Control 8.36ab 6.74ijk 6.52kl 6.38klm 5.42n 5.14n 6.43C HDPE 8.36ab 8.08abc 7.96bcd 7.78cde 7.65de 7.51ef 7.89A HDPEP 8.36ab 8.12abc 7.19fgh 6.96hij 6.33klm 6.24lm 7.20B LDPE 8.36ab 8.47a 7.41efg 6.94hij 6.18lm 5.41n 7.13B LDPEP 8.36ab 7.80cde 7.06ghi 6.59jkl 6.07m 5.22n 6.86BC Mean** 8.36A 7.84B 7.32C 6.93D 6.33E 5.90F

Sufaid (Year 1)

LSD T=0.61 W=0.16 TW=0.37


Control 8.58a 7.43ef 6.26g 6.24g 5.60h 5.35h 6.57C HDPE 8.58a 8.08b 7.99bc 7.89bcd 7.69b-e 7.56def 7.96A HDPEP 8.58a 8.05b 7.62c-f 7.22f 6.36g 6.29g 7.35AB LDPE 8.58a 8.72a 7.90bcd 7.22f 6.39g 5.61h 7.40AB LDPEP 8.58a 8.01bc 7.33ef 6.61g 6.23g 5.56h 7.05BC Mean** 8.58A 8.06B 7.42C 7.03D 6.45E 6.07F

Sufaid (Year 2)

LSD T=0.62 W=0.16 TW=0.35


48

Table 5.1: Effect of polyethylene packing on reducing sugars of “Surkh” loquat


Control 2.98a 2.82abc 2.65b-e 2.54d-h 2.32hij 2.22j 2.58AB HDPE 2.98a 2.88ab 2.72bcd 2.70b-e 2.65b-e 2.65b-e 2.76A HDPEP 2.98a 2.82abc 2.61cde 2.46e-i 2.45e-j 2.47e-j 2.63AB LDPE 2.98a 2.82abc 2.58c-f 2.57d-g 2.49d-i 2.45e-j 2.65AB LDPEP 2.98a 2.86ab 2.36f-j 2.35f-j 2.33g-j 2.25ij 2.52B Mean** 2.98A 2.84B 2.58C 2.52CD 2.45DE 2.41E

Surkh (Year 1)

LSD T=0.18 W=0.14 TW=0.20


(T) 0 2 4 6 8 10 Means* Control 3.02a 2.89ab 2.67d-h 2.45i-m 2.25no 2.19o 2.58BC HDPE 3.02a 2.89ab 2.76b-f 2.70b-g 2.68c-g 2.66e-h 2.78A HDPEP 3.02a 2.86abc 2.66e-h 2.61f-j 2.52g-l 2.42j-n 2.68B LDPE 3.02a 2.83a-e 2.61f-i 2.59f-k 2.46i-m 2.40lmn 2.65BC LDPEP 3.02a 2.86a-d 2.49h-m 2.40k-n 2.32mno 2.32mno 2.57C Mean** 3.02A 2.86B 2.64C 2.55D 2.44E 2.40E

Surkh (Year 2)

LSD T=0.10 W=0.07 TW=0.16

Table 5.2: Effect of polyethylene packing on reducing sugars of “Sufaid” loquat


Control 2.85a 2.80ab 2.58a-d 2.56a-d 2.55a-d 2.24d 2.59 ns HDPE 2.85a 2.84a 2.73abc 2.63a-d 2.58a-d 2.60a-d 2.70 ns HDPEP 2.85a 2.80ab 2.55a-d 2.58a-d 2.48a-d 2.39cd 2.61 ns LDPE 2.85a 2.86a 2.69abc 2.57a-d 2.42bcd 2.48a-d 2.64 ns LDPEP 2.85a 2.87a 2.43bcd 2.41cd 2.37cd 2.28d 2.53 ns Mean** 2.85A 2.83A 2.60B 2.55BC 2.48BC 2.40C

Sufaid (Year 1)

LSD T=0.19 W=0.16 TW=0.32


(T) 0 2 4 6 8 10 Means* Control 2.97a 2.87ab 2.59f-i 2.49g-j 2.36jk 2.22k 2.58B HDPE 2.97a 2.86abc 2.77a-f 2.67c-g 2.65d-h 2.68b-g 2.76A HDPEP 2.97a 2.84a-d 2.68b-g 2.64d-h 2.54g-j 2.52g-j 270A LDPE 2.97a 2.86abc 2.68b-g 2.61e-h 2.45hij 2.46hij 2.67AB LDPEP 2.97a 2.81a-e 2.52g-j 2.45hij 2.39ijk 2.35jk 2.58B Mean** 2.97A 2.85B 2.65C 2.57C 2.48D 2.44D

Sufaid (Year 2)

LSD T=0.09 W=0.07 TW=0.17

HDPE= High density polyethylene HDPEP= High density polyethylene (perforated) LDPE= Low density polyethylene LDPEP= Low density polyethylene (perforated) ns = Non significant *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)

49

Table 6.1: Effect of polyethylene packing on non-reducing sugars of “Surkh” loquat


Control 5.87ab 5.64abc 5.65abc 4.79fgh 4.21i-l 3.75lm 4.98B HDPE 5.87ab 5.83ab 5.79fgh 5.59abc 5.44a-d 5.29cde 5.63A HDPEP 5.87ab 5.52a-d 5.35b-e 4.91efg 4.29ijk 3.86klm 4.96B LDPE 5.87ab 5.80ab 5.50a-d 4.60ghi 4.09jkl 3.41m 4.87B LDPEP 5.87ab 5.83ab 5.85ab 5.11def 4.38hij 3.81lm 5.13B Mean** 5.87A 5.73AB 5.62B 5.00C 4.48D 4.02E

Surkh (Year 1)

LSD T=0.43 W=0.18 TW=0.42


(T) 0 2 4 6 8 10 Means* Control 5.80abc 5.67abc 5.77abc 4.86fg 4.39i 3.47j 4.99B HDPE 5.80abc 6.08a 5.80abc 5.61bcd 5.44cde 5.25de 5.66A HDPEP 5.80abc 5.66abc 5.65a-d 4.79fgh 4.31i 3.85j 5.01B LDPE 5.80abc 5.89abc 5.63bcd 4.65ghi 4.45hi 3.76j 5.03B LDPEP 5.80abc 6.02ab 5.83abc 5.15ef 4.56ghi 3.65j 5.17B Mean** 5.80A 5.86A 5.74A 5.01B 4.63C 4.00D

Surkh (Year 2)

LSD T=0.38 W=0.16 TW=0.35

Table 6.2: Effect of polyethylene packing on non-reducing sugars of “Sufaid” loquat


Control 5.77ab 4.55f-i 3.89i-l 3.85jkl 3.10m 3.25lm 4.07C HDPE 5.77ab 5.37abc 5.40abc 5.34a-d 5.25a-e 5.14b-f 5.38A HDPEP 5.77ab 5.42abc 5.06c-f 4.65e-h 4.00h-k 4.03h-k 4.82AB LDPE 5.77ab 5.93a 5.15b-f 4.67d-h 4.01h-k 3.34klm 4.83AB LDPEP 5.77ab 5.21b-f 4.95c-g 4.35g-j 3.93ijk 3.60klm 4.63BC Mean** 5.77A 5.30B 4.89C 4.57D 4.06E 3.89E

Sufaid (Year 1)

LSD T=0.64 W=0.26 TW=0.58


(T) 0 2 4 6 8 10 Means* Control 5.76ab 4.70d 3.79f 3.87ef 3.35g 3.23g 4.12C HDPE 5.76ab 5.36bc 5.36bc 5.36bc 5.17c 5.01cd 5.33A HDPEP 5.76ab 5.35bc 5.07cd 4.71d 3.94ef 3.89ef 4.79AB LDPE 5.76ab 6.00a 5.35bc 4.74d 4.06ef 3.27g 4.86AB LDPEP 5.76ab 5.34bc 4.93cd 4.27e 3.96ef 3.32g 4.69BC Mean** 5.76A 5.35B 4.90C 4.59D 4.09E 3.74F

Sufaid (Year 2)

LSD T=0.61 W=0.16 TW=0.37


50

14.9% were recorded in LDPEP during both years. Statistically HDPE proved to be

superior as compared to other treatments. In “Sufaid” loquat, no significant difference

among treatments was observed during the first year, however, lowest losses (5.3%) were

recorded in HDPE. During the second year, HDPE, HDPEP and LDPE were statistically

similar. LDPE was also at par with LDPEP and control. Lowest loss 7.1% was recorded

in HDPE followed by 9.1% in HDPEP. Maximum losses (13.1%) were recorded in both,

control and LDPEP. Reducing sugars also decreased in all treatments of both “Surkh”

and “Sufaid” loquat during both years.

2.6.4.3 Non reducing sugars

HDPE retained maximum non reducing sugars, while all other treatments were

statistically similar in effect during both years of study in “Surkh” cultivar (Table 6.1).

With respect to day one only 4.1% and 2.4% losses occurred in HDPE during both years

as compared with 15.2% and 14% in control. During the first year HDPE maintained the

level of non reducing sugars in the first two weeks while during the second year, there

was an increase in non reducing sugars in the same period. LDPE had the highest loss

(17.1%) during the first year while during the second year, highest loss (14%) was

recorded in control. At the end of tenth week, LDPE had maximum loss of 41.9% in the

first year while during the second year, control had maximum loss of 40.2% at the end of

tenth week.

In “Sufaid” loquat, treatment means show highly significant results of HDPE

which maintained the highest non reducing sugars with only 6.8% and 7.5% losses

occurring during both years compared to 29.5% and 28.5% in control. At the end of tenth

Deleted: Appendix

51

week, control had the highest losses (43.7% and 43.9%) during both years of study.

HDPEP, LDPE and LDPEP had 30.2%, 42.1% and 37.6% loss respectively during the

first year while the same treatments had 32.5%, 43.2% and 42.4% loss in the second year.

Non reducing sugars decreased during storage in both cultivars.

Flavor is a key factor of consumer satisfaction and effects the consumption of

fruits and foods (Pelayo et al., 2003). Whereas low temperatures may increase the

storage period of loquat, it does not control the decline of organic acids and moisture

losses during long storage periods (Ding et al., 1998b). Therefore, MAP storage has to

be combined with low-temperature storage to enhance its beneficial effects. Low

temperature storage combined with MAP has been known to reduce losses in organic

acids and maintained total sugars (Ding et al., 2002).

Results of the study show that HDPE significantly reduced losses in total sugars

of both varieties of loquat whereas decline in control and other treatments was more

resulting in higher losses. At the end of tenth week HDPE had only 5.2% and 4.2% total

sugar loss in Surkh while 5.6% and 7.2% loss was recorded in Sufaid loquat. Losses in

reducing sugars were 7.4% and 7.5% in Surkh while 5.3% and 7.1% losses were recorded

in Sufaid during both years respectively, which were lowest compared to other

treatments. In case of non reducing sugars, HDPE had 4.1% and 2.4% loss in Surkh

loquat whereas 6.8% and 7.5% losses occurred in Sufaid loquat which was the lowest in

regard to other treatments. All sugars decreased gradually during storage. Amaros et al.

(2008) observed that fructose, glucose and sucrose content of loquat stored for six weeks,

decreased during storage. However MAP significantly delayed the losses. Ding et al.

52

(1997) reported that total sugars did not vary markedly in polyethylene film (PE-20, PE-

30 and PE-50) and in perforated PE bags (as control) and stored at 5 °C, although sucrose

decreased steadily during storage. Melo and Lima (2003) observed that PVC 20 and 30

had the highest sucrose and total sugar contents. However, there was no notable

hydrolysis of sucrose or decrease in glucose during the early days of storage. Sugar

hydrolysis was lower in PVC 20 and 30 during the storage a compared to other

treatments. However the PVC 20 proved to be the most economical treatment for post-

harvest conservation of loquat when used for storage in a period of 50 days. Similarly

Ding et al. (1998a) observed that there was a slight increase in total sugar concentrations

during for the first 5 days of storage after which it decreased in the fruit stored at 10 and

20 °C. However, in fruit stored at 1 and 5 °C, there was no significant change during the

first 30 days of storage. Our results are also in accordance with the findings of the work

reported above.

2.6.5. Effect on Titratable Acidity

Titratable acidity (TA) of “Surkh” cv. of loquat fruit decreased with the

passage of time in all treatments as depicted in Table 7.1 during the ten week storage

period. Maximum TA (0.52% and 0.49%) was retained in high density polyethylene

(HDPE) during both years. Minimum TA was recorded in control and perforated low

density polyethylene (LDPEP) during both years. The storage periods showed a

decreasing trend of TA with passage of time in both years. The two year data also reveal

that HDPE retained TA till the first two weeks with only a slight decrease as compared to

Deleted: Appendix

53

A

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8 10

Titra

tabl

e Ac

idity

(%)

C

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8 10

B

0.0

0.2

0.4

0.6

0.8

1.0


Titra

tabl

e Ac

idity

(%)

D

0.0

0.2

0.4

0.6

0.8

1.0


Contro;l

HDPE

HDPEP

LDPE

LDPEP

Fig. 5: Effect of polyethylene packaging on titratable acidity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.05, B = 0.05, C = 0.05, D = 0.05


54

Table 7.1: Effect of polyethylene packing on titratable acidity of “Surkh” loquat


Control 0.61 b 0.34 hi 0.30 i 0.33 hi 0.20 j 0.19 j 0.33D HDPE 0.61 b 0.723 a 0.51 cd 0.47 de 0.43 efg 0.40fg 0.52A HDPEP 0.61 b 0.503 cd 0.48 de 0.32 hi 0.40 fg 0.22 j 0.42C LDPE 0.61 b 0.44 ef 0.54 c 0.55bc 0.37 gh 0.34 hi 0.47B LDPEP 0.61 b 0.43 efg 0.30 i 0.20 j 0.21 j 0.18 j 0.32D Mean** 0.61A 0.48B 0.42C 0.37D 0.32E 0.26F

Surkh (Year 1)

LSD T=0.02 W=0.02 TW=0.05


(T) 0 2 4 6 8 10 Means* Control 0.59 a 0.39 fg 0.31 jkl 0.25 lmn 0.21 mno 0.18 o 0.32C HDPE 0.59 a 0.57 ab 0.51 cd 0.47 de 0.44 ef 0.39 fgh 0.49A HDPEP 0.59 a 0.53 bc 0.48 cde 0.33 hij 0.31 jk 0.21 mno 0.41B LDPE 0.59 a 0.43 ef 0.43 ef 0.37 ghi 0.33 ij 0.26 klm 0.40B LDPEP 0.59 a 0.42 efg 0.33ij 0.22mno 0.20 no 0.17o 0.32C Mean** 0.59A 0.47B 0.41C 0.33D 0.29E 0.24F

Surkh (Year 2)

LSD T=0.02 W=0.02 TW=0.05

Table 7.2: Effect of polyethylene packing on titratable acidity of “Sufaid” loquat


Control 0.54 b 0.41 c 0.25 ih 0.37 c-f 0.30ghi 0.23 j 0.35B HDPE 0.54b 0.50 b 0.61 a 0.56 b 0.53 b 0.38 cde 0.52A HDPEP 0.54 b 0.35 d-g 0.29 hi 0.19 j 0.10 k 0.13 k 0.27C LDPE 0.54 b 0.36 c-g 0.38 cde 0.40 cd 0.33 e-h 0.20 j 0.36B LDPEP 0.54 b 0.22 j 0.31 fgh 0.29 hi 0.19 j 0.14 k 0.28C Mean** 0.54A 0.37B 0.37B 0.36B 0.29C 0.21D

Sufaid (Year 1)

LSD T=0.03 W=0.02 TW=0.05



Control 0.54 a 0.36 ef 0.28 hi 0.28 ghi 0.24 ij 0.18 kl 0.31C HDPE 0.54 a 0.53 a 0.51 a 0.48 ab 0.44 bc 0.37 def 0.48A HDPEP 0.54 a 0.48 ab 0.34 ef 0.26 ij 0.21 jk 0.15 l 0.33C LDPE 0.54 a 0.42 cd 0.39 cde 0.36 ef 0.33 fgh 0.22 jk 0.38B LDPEP 0.54 a 0.42 cd 0.34 efg 0.25 ij 0.17 kl 0.14 l 0.31C Mean** 0.54A 0.44B 0.37C 0.33D 0.28E 0.21F

Sufaid (Year 2)

LSD T=0.02 W=0.02 TW=0.05

Deleted: ¶

55

other treatments, after which it also started to decline. At the end of tenth week, HDPE

maintained the highest TA compared to rest of the treatments (Fig. 5).

In “Sufaid” cv. maximum TA (0.52% and 0.48%) during both years was also

retained by HDPE (Table 2.2) followed by the fruit packaged in LDPE which had

higher TA than other treatments. Control, HDPEP and LDPEP were statistically at par

with each other. A significant decrease in TA as compared to the day of harvest was

observed after two weeks storage which remained unchanged till the end of six weeks

and then a significant decline was observed during rest of the storage period in the first

year. However a constant significant decrease in TA on every storage interval was

observed during the second year. HDPE retained its TA content as compared to other

treatments till the eighth week after which a slight decrease was recorded. Maximum

losses were recorded in HDPEP in the eighth week during the first year, while HDPEP

and LDPEP had greater losses in the tenth week in the second year.

Organic acids are an important parameter in maintaining the quality of fruits. In

loquat malic acid is the principal acid contributing 90% of the total organic acid content

(Ding et al.,1998a). Titratable acidity is directly related to the concentration of organic

acids present in the fruits. In high quality loquat it ranges from 0.3% to 0.6% (Ding,

2007). Other studies also found that use of polyethylene bags minimizes reduction in

organic acids (Ding et al., 1997). Ding et al. (1998a) reported that loquat fruit packaged

in polyethylene film bags with 0.15% perforations retained their initial quality and

chemical constituents for one month when stored at 1 and 5°C, similarly Akbudak and

Deleted: Appendix

56

Eris (2004) also reported that MAP retarded the decrease in titratable acidity of peaches

and nectarines.

During storage it was observed that both non perforated treatments maintained

higher acidity as compared to control followed by perforated treatments. Greater loss of

acidity in control and perforated PE packages might be due to rapid consumption of malic

acid by the microorganisms as a carbon source whereas decrease in acidity due to

fermentation or break up of acids to sugars in fruits during respiration in storage

conditions has been suggested by Ball (1997). Polyethylene bags of different thickness

have known to be effective in reducing decline of organic acid in loquat during storage

(Ding et al., 2002; Melo and Lima, 2003) which support the results of this study

2.6.6. Effect on SOD Activity

SOD activity of “Surkh” cultivar was high (48.06 and 47.36 U/g FW ) in HDPE

during both years followed by HDPEP (40.85 and 40.30 U/g FW) while both low density

packages had significantly low activity during both years (Table 8.1). Control and low

density polyethylene packages had low SOD activity compared to high density

polyethylene treatments. Storage periods means reveal that SOD activity was high during

the first four weeks and fluctuated till the eight weeks, thereafter it declined during the

last two weeks (Fig. 6). During the second year, almost same trend was observed. HDPE

had the highest activity (47.36 U/g FW) followed by HDPEP (40.30 U/g FW ), however

lowest activity (29.40 U/g FW ) was recorded in HDPEP during the tenth week.

Deleted: )

Deleted: Appendix

57

A

0

20

40

60

80

0 2 4 6 8 10

SOD

Act

ivity

(U/g

FW

)

C

0

20

40

60

80

0 2 4 6 8 10

B

0

20

40

60

80


SOD

Act

ivity

(U/g

FW

)

D

0

20

40

60

80

0 2 4 6 8 10



Fig. 6: Effect of polyethylene packaging on SOD activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 4.36, B = 3.87, C = 2.24, D = 2.71


Formatted Table

Formatted: Indent: Left: 0.05"

Deleted:

A

0

20

40

60

80

0 2

U/g

FW

Deleted:

B

0

20

40

60

80

0 2 4Storag

U/g

FW

Deleted: Section Break (Next Page)

58

Table 8.1: Effect of polyethylene packing on SOD of “Surkh” loquat


Control 42.60f 47.93de 26.10kl 35.13hi 30.67ijk 37.27gh 36.62C HDPE 42.60f 55.87ab 51.00cd 59.47a 43.27f 36.17h 48.06A HDPEP 42.60f 45.13ef 33.47hij 36.07h 53.57bc 34.27hij 40.85B LDPE 42.60f 36.30h 41.17fg 32.80hij 33.97hij 32.83hij 36.61C LDPEP 42.60f 25.13l 33.60hij 33.83hij 25.83l 20.23jkl 31.71D Mean** 42.60A 42.07A 37.07C 39.46B 37.46C 33.95D

Surkh (Year 1)

LSD T=2.88 W=1.95 TW=4.36


(T) 0 2 4 6 8 10 Means* Control 47.93bc 41.63d 32.10fgh 33.03fgh 31.77fgh 30.07ghi 36.09D HDPE 47.93bc 56.67a 43.53cd 59.07a 41.47d 35.47ef 47.36A HDPEP 47.93bc 45.47cd 43.43cd 29.20hij 29.20hij 29.40hi 40.30B LDPE 47.93bc 50.07a 41.47d 35.47ef 47.93bc 32.60fgh 38.51C LDPEP 47.93bc 25.03j 51.20b 36.17ef 28.77hij 34.07efg 37.19D Mean** 47.93A 43.95B 41.55C 40.18C 33.39D 32.32D

Surkh (Year 2)

LSD T=1.20 W=1.74 TW=3.87

Table 8.2: Effect of polyethylene packing on SOD of “Sufaid” loquat


Control 45.53b 33.10ghi 23.93l 24.47l 19.97m 26.20kl 28.87D HDPE 45.53b 35.93efg 49.37a 34.43fgh 38.53d 34.70fgh 39.68A HDPEP 45.53b 33.87f-i 43.53bc 35.30efg 37.60de 31.57i 37.90B LDPE 45.53b 34.07fgh 24.13l 38.40d 32.20hi 25.23l 33.26C LDPEP 45.53b 42.17c 35.93ef 28.67j 27.83jk 25.20l 34.22C Mean** 45.53A 35.75B 35.38B 32.25C 31.23D 28.58E

Sufaid (Year 1)

LSD T=1.59 W=1.00 TW=2.24


(T) 0 2 4 6 8 10 Means* Control 49.37a 29.37kl 32.10ijk 31.17jk 27.00lm 24.60m 32.27C HDPE 49.37a 46.17b 35.00ghi 38.30def 40.23cd 31.47jk 40.09A HDPEP 49.37a 38.57cde 37.03efg 34.83ghi 32.33ijk 30.07k 37.03B LDPE 49.37a 45.80b 41.40c 40.40cd 35.47fgh 33.50hij 40.99A LDPEP 49.37a 40.13cd 20.00n 31.37jk 27.03lm 27.00lm 32.48C Mean** 49.37A 40.01B 33.11D 35.21C 32.41D 29.33E

Sufaid (Year 2)

LSD T=1.57 W=1.21 TW=2.71


59

SOD activity in HDPE of “Sufaid” cultivar was significantly high (39.68 and

40.09 U/g FW ) followed by HDPEP during both years (Table 8.2). The lowest activity

was recorded in control. Both perforated treatments were statistically similar during the

first year whereas LDPE showed higher activity during the second year. The activity

gradually declined during storage. High activity (49.37 U/g FW) was observed in HDPE

during the first year followed by HDPEP (43.53 U/g FW) whereas HDPE and LDPE had

highest SOD activity (46.17 and 45.80 U/g FW) in the next year.

Research shows that antioxidative enzymes have a major role in postharvest

stress in fruits (Fernandez et al., 2007). Among these enzymes, SOD is the first enzyme

which is activated during peroxidation reactions. The production of H2O2 acts as a

chemical messenger during stress conditions before it is metabolized by catalase and

peroxidase (Neill et al., 2002). The enzyme exists in subcellular compartments and all

aerobic organisms which are liable to oxidative stress (Blokhina et al., 2003). SOD and

catalase together, converts the dangerous superoxide radical and hydrogen peroxide to

molecular oxygen and water, thus avoiding damage to the cells (Scandalios, 1993a).

The first physiological effects on fruit metabolism in a modified atmosphere is a

decreased respiratory intensity during storage which involves a decreased substrate

consumption, CO2 production, O2 consumption and release of heat. High CO2

concentrations effect O2 consumption rates (Kader et al., 1989). Zheng et al. (2000b)

reported a decrease in respiration rate of loquat fruit stored in polyethylene bags of 0.04

mm thickness and containing 90% O2 at 1°C for 35 days.

Deleted: Appendix

60

Our results show that SOD activity decreased during the entire storage period.

Similar results have also been reported by Gong et al. (2001), Wang et al. (2005) and

Kondo et al.(2005). HDPE and LDPE treatments retained higher SOD activity as

compared to control and perforated treatments. This might be due to the fact that the

degree of oxidative stress in these treatments might have been less serious compared

with control fruit, for the activities of SOD remained high. Higher SOD activity in

controlled atmosphere and MAP treatments as compared to control after 30 day storage

of loquat has also been reported by Ding et al. (2006). MAP conditions may be more

effective in reducing oxidative stress in stored fruits. However in the present study, no

correlation exists between SOD and CAT activities. Such findings have also been

reported by Spychalla and Desborough (1990) and Kawakami et al. (2000). These

observations might be explained by the CAT not working until H2O2 concentration

increased beyond a certain threshold, since CAT possesses a very low affinity for H2O2

(Kawakami et al., 2000).

It has been reported that an increase in SOD activity promotes cytotoxicity as a

result of accelerated formation of H2O2, and generation of the hydroxyl radical

(Kawakami et al., 2000). The reduced release of O2- radicals by sound or un-injured

tissues might have reduced the synthesis or need for SOD activation. This shows that

healty and sound tissues have more capacity to produce SOD because of less injured

cells (De Martino et al., 2006).

61

2.6.7 Effect on Catalase Activity

Treatment means of Catalase (CAT) activity of “Surkh” cultivar presented as log

values in Table 9.1, reveal significantly higher CAT activity in non perforated as

compared to perforated packages and control during both years. CAT activity during both

years, increased in the first two weeks after which it decreased till the end of storage

with a surge in activity during the eighth week. All treatments except HDPE had high

activity in the second week. In LDPE the activity was higher during the fourth week

(3.22 U/g FW). HDPE, HDPEP and LDPEP showed higher activity during the eight week

also, which continued until tenth week in HDPE and LDPE (3.19 and 3.09 U/g FW). A

similar pattern of activity was observed during the second year. All treatments except

LDPEP showed higher activity until fourth week after which it decreased. An increase

was again observed in HDPE and HDPEP during the eighth week. In HDPE it continued

till the end of storage.

Average treatments means of “Sufaid” cultivar indicate that HDPE had

significantly higher activity during both years, while during the first year it was

statistically similar to HDPEP and LDPEP. Activity in control was lowest during both

years. An increase in CAT activity in all treatments was observed in the second week

(Table 8.2) during both years after which it started to decline whereas a surge in the

eighth week was recorded in the first year. In the last four weeks HDPE showed higher

activity during both years (Fig. 7).

During respiratory metabolism, CAT decomposes H2O2, into H2O and O2 and

prevents H2O2 from accumulating in fruit and vegetable tissues. Fruits sealed in PE bags

Deleted: Appendix

Deleted: Appendix

62

A

0

1000

2000

3000

0 2 4 6 8 10

U/g

FW

C

0

1000

2000

3000

0 2 4 6 8 10

B

0

1000

2000

3000


U/g

FW

D

0

1000

2000

3000

0 2 4 6 8 10


Contro;l

HDPE

HDPEP

LDPE

LDPEP

Fig. 7: Effect of polyethylene packaging on catalase activity in loquat cv. “Surkh” during

1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.05, B = 0.06, C = 0.11, D = 0.06


63

Table 9.1: Effect of polyethylene packing on catalase activity of “Surkh” loquat


Control 2.47i 3.16a-d 3.01def 2.5hi 2.52hi 2.28j 2.65B HDPE 2.47i 3.03c-f 2.90f 2.63gh 3.14a-d 3.19ab 2.89A HDPEP 2.47i 3.16abc 2.27j 2.43i 3.05bcde 2.40ij 2.63B LDPE 2.47i 3.08a-e 3.22a 2.70g 2.52hi 3.09a-d 2.84AB LDPEP 2.47i 3.14a-d 2.68g 2.53hi 3.05b-e 2.95ef 2.80AB Mean** 2.47E 3.11A 2.81BC 2.55D 2.85B 2.78C

Surkh (Year 1)

LSD T=0.21 W=0.12 TW=0.05


(T) 0 2 4 6 8 10 Means* Control 2.8f-i 3.08abc 3.09abc 2.75g-j 2.58j-m 2.33n 2.77C HDPE 2.8f-i 3.22a 3.03bcd 2.87d-g 3.13ab 3.02bcd 3.01A HDPEP 2.8f-i 2.80f-i 3.03bcd 2.63i-m 3.03bcd 2.51lm 2.80C LDPE 2.8f-i 3.14ab 3.06abc 2.82e-h 2.68h-l 2.95c-f 2.91B LDPEP 2.8f-i 2.98b-e 2.74g-j 2.52k-m 2.69g-k 2.46mn 2.70D Mean** 2.8C 3.10A 2.94B 2.72D 2.82C 2.65D

Surkh (Year 2)

LSD T=0.07 W=0.15 TW=0.06

Table 9.2: Effect of polyethylene packing on catalase activity of “Sufaid” loquat


Control 2.78c-f 3.02a-d 2.87b-e 2.72def 2.41gh 2.32h 2.68C HDPE 2.78c-f 3.04a-d 2.54fgh 241gh 3.19a 3.17ab 2.85AB HDPEP 2.78c-f 3.22a 3.07abc 2.91a-e 2.76c-f 2.80c-f 2.92A LDPE 2.78c-f 3.05abc 2.51fgh 2.34gh 2.94a-e 2.64efg 2.71BC LDPEP 2.78c-f 3.13ab 2.53fgh 2.53fgh 2.96a-d 2.64efg 2.76ABC Mean** 2.78BC 3.09A 2.70C 2.58D 2.85B 2.71C

Sufaid (Year 1)

LSD T=0.15 W=0.26 TW=0.11


Control 2.85cde 3.12ab 2.82cdef 2.66fgh 2.45I 2.29J 2.71D HDPE 2.85cde 3.24a 2.98bc 2.86cde 3.12ab 2.98bc 3.00A HDPEP 2.85cde 3.16a 2.97bc 2.78def 2.69efg 2.57ghi 2.84C LDPE 2.85cde 3.13ab 2.93cd 2.70efg 2.81c-f 2.52hi 2.82C LDPEP 2.85cde 3.2a 2.98bc 2.86cde 2.87cd 2.58ghi 2.89B Mean** 2.86C 3.17A 2.93B 2.77D 2.77D 2.59E

Sufaid (Year 2)

LSD T=0.04 W=0.14 TW=0.06 HDPE= High density polyethylene HDPEP= High density polyethylene (perforated) LDPE= Low density polyethylene LDPEP= Low density polyethylene (perforated) *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)

64

bags having low permeability to gases creates a modified atmosphere. During respiration

in such an atmosphere O2 level in the bags declines while CO2 level increases (Kader,

1997) causing a decrease in the respiration rate of the fruit. CAT activity of loquat stored

in controlled atmosphere conditions have known to increase within first 15 days and then

a gradual decline with storage time (Wang et al., 2005). The results of this study also

show an increase in CAT activity during the first two weeks of storage which might be

due the accumulation of respiratory H2O2 due to high rate of respiration whereas

decreased CAT activity during the later weeks suggests lesser capacity of the cell to

scavenge H2O2 (Ng et al., 2005). The results also indicate that HDPE maintained higher

CAT activity which shows that it had a role in protection against oxidative damage as

described by Ng et al. (2005).

2.6.8. Effect on POD Activity

POD activity in fruit of cv. “Surkh” loquat during the first year was

significantly high in HDPEP followed by both low density packages, however, during the

second year, control had significantly higher activity. Minimum activity during both

years was recorded in HDPE (Table 10.1). LDPE and LDPEP were statistically similar

to control. During the second year, both perforated treatments were statistically similar in

effect (Fig. 8). Treatments reveal that activity kept on changing during the ten week

storage period. Decrease in activity was observed during both years after the fourth week

after which it started to increase, reaching its maximum in the last week.

No significant effect of packages on POD activity in fruit of cv. “Sufaid” was

observed during the first year, however, during the second year, both non perforated

Deleted: Appendix

65

A

1

2

3

4

5

0 2 4 6 8 10

U/g

FW

C

1

2

3

4

5

0 2 4 6 8 10 B

1

2

3

4

5

0 2 4 6 8 10


U/g

FW

D

1

2

3

4

5


U/g

FW

Contro;l HDPE HDPEPLDPE LDPEP

Fig. 8: Effect of polyethylene packaging on POD activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.13, B = 0.08, C = 0.07, D = 0.08


66

Table 10.1: Effect of polyethylene packing on POD activity of “Surkh” loquat


Control 2.26 l 2.56 k 3.54ef 2.56k 3.66cd 3.66cd 3.04B HDPE 2.26 l 2.74 j 3.38 g 2.66 j 2.73 j 3.52 ef 2.88C HDPEP 2.26 l 3.01 hi 3.48 fg 2.24 l 3.91 a 3.81 b 3.12A LDPE 2.26 l 3.04 hi 3.74 bc 2.53 k 3.01 hi 3.59 de 3.03B LDPEP 2.26 l 3.09 h 3.54 ef 2.98 hi 2.95 i 3.38 g 3.03B Mean** 2.26F 2.89D 3.54B 2.59E 3.26C 3.59A

Surkh (Year 1)

LSD T=0.05 W=0.04 TW=0.13


Control 2.40j 2.74i 3.59b 3.96a 3.67b 3.92a 3.38A HDPE 2.40j 2.26k 3.35ef 3.29f 3.08gh 3.47cd 2.97D HDPEP 2.40j 2.77i 3.67b 3.38de 2.40j 3.62b 3.04C LDPE 2.40j 2.25k 3.46cd 3.69b 3.41cde 3.49c 3.11B LDPEP 2.40j 2.78i 3.68b 3.01h 3.13g 3.44cde 3.07C Mean** 2.40E 2.56D 3.55A 3.46B 3.13C 3.59A

Surkh (Year 2)

LSD T=0.04 W=0.04 TW=0.08

Table 10.2: Effect of polyethylene packing on POD activity of “Sufaid” loquat


Control 2.30 q 2.69 o 3.34 hi 2.91 l 4.08 a 3.99 b 3.22A HDPE 2.30 q 2.96 l 3.56 d 2.83 m 2.84 m 3.69 c 3.03B HDPEP 2.30 q 2.80 m 3.26 j 2.71 no 3.39 fgh 3.45 ef 2.99B LDPE 2.30 q 2.61 p 3.63 c 3.05 k 3.44 efg 3.29 ij 3.05B LDPEP 2.30 q 2.61 p 3.37 gh 2.77 mn 3.49 de 3.45 efg 3.01B Mean** 2.30E 2.74D 3.43B 2.86C 3.45B 3.58A

Sufaid (Year 1)

LSD T=0.07 W=0.03 TW=0.07


(T) 0 2 4 6 8 10 Means* Control 2.31m 3.01i 3.13h 3.89a 3.37f 3.95a 3.28A HDPE 2.31m 2.84j 3.57bcd 3.55cd 3.01i 3.56bcd 3.14B HDPEP 2.31m 2.25m 3.38ef 3.10hi 2.85j 3.59bc 2.91C LDPE 2.31m 2.54l 3.38ef 3.54cd 3.47de 3.65b 3.15B LDPEP 2.31m 2.66k 3.24g 3.50cd 2.64k 3.38ef 2.95C Mean** 2.31F 2.66E 3.34C 3.51B 3.07D 3.62A

Sufaid (Year 2)

LSD T=0.06 W=0.04 TW=0.08


67

packages had significantly higher activity. Maximum activity during both years was

recorded in control. Treatment means of “Sufaid” cv. (Table 10.2) show that during the

two year study, control had the highest activity (3.22 and 3.28 U/g FW ). Packages

treatments had no significant effect on POD activity on fruit stored during the first year.

During the second year, HDPE and LDPE were at par while the lowest activity (2.91 and

2.95 U/g FW ) was recorded in both perforated packages. Overall activity kept on

changing during storage and reached its maximum at the tenth weeks in storage at 4 °C.

Flesh browning in loquat is a major concern related to quality deterioration of

loquat fruit and is linked with phenol-related metabolic enzymes POD and PPO (Loaiza

and Saltveit, 2001). It is a symptom of loquat fruit decay and is caused by oxidative

reactions of phenolic compounds by oxidases (PPO and POD) which result due to the

loss of cell compartments due to physical or physiological stresses (Ding et al., 2006).

Peroxidase may indirectly enhance the browning processes by detoxifying peroxides

using antioxidant as substrates, thus catalyzing the transfer of electrons to peroxides and

oxidizing compounds which may play an active role in browning prevention (Rojas et al.,

2007). Contrary to CAT, POD catalyzes the decomposition of H2O2, by liberating free

radicals instead of oxygen (Burris, 1960).

Amongst different techniques used to extend the shelf life of fresh and perishable

horticultural crops, modified atmospheric packaging (MAP) has been reported as a cost

effective and successful technique (Amin et al., 2001; Banaras et al., 2005; Zagham,

2003). MAP improves the retention of ascorbic acid, carotinoids, chlorophyll and

polyunsaturated fatty acids levels compared to air storage (Zhuang et al., 1994; Barth and

Deleted: Appendix

68

Zhang, 1996). Perforated polyethylene packages are used for most products to allow

exchange of gases and avoid excessive humidity whereas, solid polyethylene packages

are used to seal the products and provide a modified atmosphere by reducing the amount

of oxygen available for respiration and ripening.

Our results show that there was a fluctuation in POD activity during the ten week

storage period, however compared to day zero, POD activity had increased by the end of

tenth week in all treatments. According to Ding et al. (2006), POD activity is known to

fluctuate during storage of loquat. He found no significant change in fruit stored in air

and in MAP at 6 °C, however, a significant increase was observed on 49 d in MAP at

1 °C. Similarly Zhang and Zhang (2008) stated that POD activity of pomegranate peel

increased gradually with great fluctuation during storage. In this study non perforated

treatments had lesser increase in POD activity as compared to control and perforated

treatments.

Reports of increased POD activity during storage have also been reported in other

fruits as well. El-hilali et al. (2003) reported that POD specific activity in mandarin

increased continuously during a 30 day storage period at 4 °C while POD activity

increased in squash during storage at 5°C (Wang, 1995). Tian et al. (2004) also observed

an increase in POD activity of sweet cherry fruit with advancing senescence after 50 days

of storage. The increase in POD activity might be due to a need to detoxify H2O2

generated during senescence (Neill et al., 2002). Our results are in accordance with

findings of the above mentioned scientists who have reported an increase in POD activity

in fruits during storage.

69

2.6.9 Effect on Ascorbic Acid Content

Different densities of polyethylene, with or without perforations did not

significantly alter the ascorbic acid (AA) content of “Surkh” cultivar of loquat during

both years, however, all polyethylene treatments retained high AA content throughout

storage as compared to control. Ascorbic acid values ranged from 2.90 to 3.05 mg /100 g

during the ten week storage periods in both seasons as compared to 2.26 mg /100 g in

control. Data in Table (11.1) indicated a continuous steady decrease in AA content of

loquat fruits during ten week storage at 4 °C. This trend in reduction of AA content was

observed in all treatments including control. Different polyethylene treatments had no

significant difference among each other (P=0.05). Treatments means show that maximum

losses (2.26 and 2.29 mg/ 100 g) in AA content were recorded in control at the end of

storage period during both years, whereas highest losses (1.30 and 1.20 mg/100 g )

during the tenth week were also recorded in control. Minimum losses (3.35 and 3.30

mg/100g) were recorded in HDPE during both seasons (Fig. 9).

In “Sufaid” cultivar of loquat, a similar decreasing trend was observed during

both years of the study (Table 4.2). HDPE, HDPEP and LDPE were statistically at par

with each other, while LDPEP showed different results during the first year. During the

second year all PE package treatments were statistically similar but differed significantly

with control. Maximum losses (2.11 and 2.17 mg/100 g) were observed in control while

minimum losses were recorded in HDPE. Storage period means show that AA content

decreased continuously till the end of storage period. Highest losses (1.23 and 1.33

mg/100 g) were recorded during the tenth week in control.

Deleted: Appendix

Deleted: Appendix

70

A

1

2

3

4

0 2 4 6 8 10

Vit C

(m

g/10

0g F

W)

C

1

2

3

4

0 2 4 6 8 10

B

1

2

3

4

0 2 4 6 8 10


Vit C

(m

g/10

0g F

W)

D

1

2

3

4

0 2 4 6 8 10Storage period (weeks)


Fig. 9: Effect of polyethylene packaging on ascorbic acid content in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.17, B = 0.09, C = 0.16, D = 0.10


71

Table 11.1: Effect of polyethylene packing on ascorbic acid content of “Surkh” loquat


Control 3.20ab 2.90abc 2.80abc 1.93d 1.43e 1.30e 2.26B HDPE 3.20ab 3.20a 3.10abc 2.93abc 2.93abc 2.90abc 3.05A HDPEP 3.20ab 3.20ab 3.06abc 2.90abc 2.96abc 2.80abc 3.02A LDPE 3.20ab 3.13ab 3.00abc 2.93abc 2.90abc 2.73bc 2.98A LDPEP 3.20ab 3.13ab 2.93abc 2.83abc 2.73bc 2.63c 2.91A Mean** 3.20A 3.12AB 2.98B 2.70C 2.59CD 2.48D

Surkh (Year1)

LSD T=0.14 W=0.39 TW=0.17


(T) 0 2 4 6 8 10 Means* Control 3.26a 2.93c-g 2.83efgh 1.97j 1.45k 1.20l 2.29B HDPE 3.26a 3.16abc 3.20ab 2.92c-g 2.83e-h 2.80fgh 3.03A HDPEP 3.26a 3.26a 3.20ab 3.06a-e 2.90defg 2.83e-h 2.98A LDPE 3.26a 3.13abcd 2.96b-f 2.93c-g 2.83e-h 2.56i 2.95A LDPEP 3.26a 3.10abcd 3.00b-f 2.83e-h 2.70ghi 2.53i 2.90A Mean** 3.26A 3.10B 3.01B 2.70C 2.52D 2.34E

Surkh (Year 2)

LSD T=0.16 W=0.21 TW=0.09

Table 11.2: Effect of polyethylene packing on ascorbic acid content of “Sufaid” loquat


Control 3.16a 2.63cde 2.43e 1.80f 1.40g 1.23g 2.11C HDPE 3.16a 3.15a 3.10ab 3.06abc 3.00abc 2.86abcd 3.05A HDPEP 3.16a 3.13a 3.03abc 2.96abcd 2.90abcd 2.76a-e 2.99A LDPE 3.16a 3.11a 2.93a-d 2.96a-d 2.86a-d 2.66b-e 2.95AB LDPEP 3.16a 3.10ab 2.80a-e 2.76a-e 2.66b-e 2.53de 2.83B Mean** 3.16A 3.02A 2.86B 2.71BC 2.56CD 2.41D

Sufaid (Year1)

LSD T=0.13 W=0.36 TW=0.16


(T) 0 2 4 6 8 10 Means* Control 3.23a 2.70e-i 2.36j 1.93k 1.50l 1.33l 2.17B HDPE 3.23a 3.00abcd 2.83c-g 2.90b-f 2.80c-g 2.73d-h 2.91A HDPEP 3.23a 3.03abc 2.90b-f 2.86c-g 2.83c-g 2.76c-g 2.93A LDPE 3.23a 3.13ab 2.96bcde 2.90b-f 2.80c-g 2.66f-i 2.95A LDPEP 3.23a 3.00abcd 2.73d-h 2.60g-j 2.46ij 2.50hij 2.75A Mean** 3.23A 2.97B 2.76C 2.64D 2.48E 2.40E

Sufaid (Year 2)

LSD T=0.18 W=0.22 TW=0.10


72

Among different quality parameters of fruits and vegetables, ascorbic acid is

known to be of prime importance. Fruits and vegetables contribute about 91% of ascorbic

acid in the human diet. Acid content in fruits is known to decrease during storage

possibly due to utilization of organic acids during respiration or their conversion to

sugars (Kader, 2002a). Senescence leads to quality deterioration and losses in Vitamin C

(Watada et al., 1987). Amaros et al. (2008) states that ascorbic acid content of loquat

decreased slightly in MAP as compared to control treatments during a six week storage.

The present study also confirms these findings. Greater decrease of AA content in

control may be because ascorbic acid is very susceptible to oxidative deterioration and

the presence of oxygen causes acceleration in the process of oxidation of AA to

dehydroascorbic acid (Piga et al., 2003). In control this process may have occurred at

accelerated rate due to the presence of higher concentrations of O2 as compared to

polyethylene packages which may have retarded the oxidation process. Thus the results

of this study verify that MAP and low temperature induces minimal changes in loquat

fruit stored at 2 - 4 °C as revealed by Chen et al. (2003) and Amaros et al. (2008).

2.6.10. Effect on Radical Scavenging Activity

Radical scavenging activity (RSA) calculated in terms of percent inhibition of

DPPH shows that all PE packages treated fruits had significantly higher RSA than

control in “Surkh” cultivar of loquat during both years (Table 12.1). All PE treatments

were statistically similar during the first year, however both non perforated treatments

had higher RSA (51.14 % and 54.86%) as compared to perforated treatments during the

second year. Storage period means reveal a decrease in activity till the sixth week in all

Deleted: Appendix

73

treatments followed by an increase in the eighth week till the end of storage period in

both years. HDPE treated fruit had higher activity in the second week during both years.

Radical scavenging activity in fruit of “Sufaid” cultivar (Table 12.2) during both

years was significantly higher in all PE packages compared to control. No significant

difference was observed among different PE treatments. RSA decreased in all treatments

during the first six weeks after which it started to increase towards the end of storage

period while RSA in control started to decrease from the eight week onward as

compared to other treatments (Fig. 10). LDPE had highest RSA in the eighth and tenth

weeks during the first years study.

Fruits have notably high RSA due to their richness in antioxidants which include

vitamins and different polyphenolics, which play an important role as free radical

scavengers, however the antioxidant activity may be different between cultivars and

species (Award et al., 2001; Kondo et al., 2005). Most studies of antioxidant losses have

examined ascorbic acid as being the most reactive of the antioxidants (Shewfelt, 1995).

Amongst different techniques used to increase the postharvest life of fresh and

perishable horticultural crops, modified atmospheric packaging (MAP) has been reported

as a cost effective and successful technique (Amin et al., 2001; Banaras et al., 2005;

Zagham, 2003). MAP improves the retention of ascorbic acid, carotinoids, chlorophyll

and polyunsaturated fatty acids levels compared to air storage (Zhuang et al., 1994; Barth

and Zhang, 1996), moreover, modified atmospheres, either using controlled atmosphere

or film packages with fruits and vegetables, are beneficial in reducing hydroxyl radical

Deleted: Appendix

74

A

0

20

40

60

80

100

0 2 4 6 8 10

% In

hibi

tion

C

0

20

40

60

80

100

0 2 4 6 8 10

B

0

20

40

60

80

100

0 2 4 6 8 10

Storage period (weeks)

% In

hibi

tion

D

0

20

40

60

80

100

0 2 4 6 8 10



Fig. 10: Effect of polyethylene packaging on relative scavenging activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 7.47, B = 7.24, D = 5.20, D = 6.45


75

Table 12.1: Effect of polyethylene packing on radical scavenging activity of “Surkh” loquat


Control 59.07cd 36.60hi 41.80f-i 39.17f-i 37.67ghi 38.93f-i 42.21B HDPE 59.07cd 84.33a 45.47e-h 39.10f-i 25.03j 45.77efg 51.67A HDPEP 59.07cd 45.37efg 40.00f-i 47.17ef 72.97b 53.10de 52.94A LDPE 59.07cd 36.67hi 40.43f-i 52.80de 57.73cd 52.90de 49.93A LDPEP 59.07cd 52.07de 36.40i 41.03f-i 62.30c 54.07cde 50.82A Mean** 59.07A 51.01B 40.82C 43.85C 51.14B 48.95B

Surkh (Year 1)

LSD T=5.11 W=3.34 TW=7.47


(T) 0 2 4 6 8 10 Means* Control 61.97b 36.60ij 36.10j 36.60ij 34.77j 35.03j 40.18C HDPE 61.97b 59.40bcd 42.67g-j 51.50def 39.07hij 52.27c-f 51.14A HDPEP 61.97b 39.57hij 36.97hij 38.87hij 48.60efg 48.50efg 45.74B LDPE 61.97b 58.73bcd 37.43hij 44.80f-i 53.40cde 72.83a 54.86A LDPEP 61.97b 45.43e-h 42.67g-j 27.10k 38.40hij 60.17bc 45.96B Mean** 61.97A 47.95C 39.17E 39.77DE 42.85D 53.76B

Surkh (Year 2)

LSD T=3.93 W=3.23 TW=7.24

Table 12.2: Effect of Polyethylene packing on radical scavenging activity of “Sufaid” loquat


Control 60.77ab 39.77ef 46.73d 36.97efg 34.57fgh 33.23gh 42.01B HDPE 60.77ab 47.63d 40.77e 46.63d 54.63c 54.70c 50.86A HDPEP 60.77ab 40.00ef 39.93ef 34.67fgh 60.83ab 53.77c 48.33A LDPE 60.77ab 57.07bc 30.00h 46.77d 60.97ab 64.17a 53.29A LDPEP 60.77ab 52.30cd 29.43h 40.37ef 51.77cd 57.50bc 48.69A Mean** 60.77A 47.35C 37.37E 41.08D 52.55B 52.67B

Sufaid (Year 1)

LSD T=5.18 W=2.32 TW=5.20


(T) 0 2 4 6 8 10 Means* Control 62.10cd 38.03hij 32.23jkl 25.57lm 34.43ijk 39.63f-j 38.67C HDPE 62.10cd 78.37a 39.37f-j 29.80klm 38.33hij 62.37cd 51.72A HDPEP 62.10cd 40.70f-i 35.07ijk 38.80g-j 45.83efg 69.43b 48.66A LDPE 62.10cd 66.73bc 32.37jkl 35.43ijk 48.37e 43.63e-h 48.11A LDPEP 62.10cd 55.67d 32.93jk 24.47m 39.03g-j 46.60ef 43.47B Mean** 62.10A 55.90B 34.39E 30.81F 41.20D 52.33C

Sufaid (Year 2)

LSD T=4.60 W=2.88 TW=6.45


76

formation. Fruit RSA decreases with the advancing of senescence (Srilaong and Tatsumi,

2003). The results of this study reveal that RSA decreased during the first six weeks and

increased during the last four weeks in all treatments during storage. At the end of tenth

week, the RSA was lower than day one. Initial decrease followed by an increase in RSA

has also been observed in melon by Oms-Oliu et al.(2008), cut citrus segments (Del

Caro et al., 2004) and non-cured sweet potato roots by Padda and Picha (2008) who

attributed the increase in RSA to an increase in total phenolic compounds.

During advanced tissue senescence where membranes are damaged, the

concentration of antioxidant substances (ascorbic acid among them) in the cells may

increases to repair the damage done. The regeneration of ascorbic acid counter balances

the increased production of free radicals and reactive oxygen species which could cause

cellular injury or death (Sonia and Chaves, 2006). This could explain the rise in RSA

during the last two weeks in the present study. When analyzing the possible association

between RSA and AA content, the Pearson linear correlation coefficients were

significant (P < 0.05), being r = 0.97, 0.76 for Surkh while r =0.89 and 0.90 for Sufaid

during the first and second years respectively.

There are different reports regarding efficiency of films with different densities.

Ding et al. (2002) reported that perforated MAP packaged loquat retained higher levels

of carotenoids during storage as compared to fruit packed in low gas permeance bags.

According to Piga et al. (2002), less permeable film resulted in better retention of

antioxidant activity of segmented mandarin. In this study non perforated films had higher

77

antioxidants in both cultivars of loquat which is in conformation with the findings of the

above researchers.

2.6.11. Effect on PPO Activity

Data regarding effect of polyethylene packages on changes in PPO activity is

presented in Table 13.1. Treatments means of “Surkh” cultivar during both years show

that control had significantly higher PPO activity while lowest activity was observed in

both low density PE packages. Storage period means indicate that PPO activity increased

during the eighth week both years, however it remained high during the tenth week in

the first year while during the second year, it was comparatively low. Control had high

activity from fourth to eighth weeks, while in rest of the treatments it fluctuated during

both years.

Table 13.2 shows that in “Sufaid” cv also higher PPO activity was recorded in

control during both years of study. Both low density packages were statistically similar in

effect. HDPE showed high activity during both the years. Overall, PPO activity increased

during the first eight weeks after which a decline was observed in all treatments till the

end of storage (Fig. 11). Control generally had high activity in the last four weeks of

both years. , while HDPE had the highest activity (73.84 U/g FW and 71.25 U/g FW in

the sixth week during both years.

PPO activity has been known to increase gradually during storage of loquat at low

temperatures (Cai et al., 2006d) and is attributed to moisture loss and high pH (Bryant,

2004). The use of refrigeration combined with impermeable packaging effectively

Deleted: Appendix

Deleted: Appendix

78

A

0

20

40

60

80

100

0 2 4 6 8 10

U/g

FW

C

0

20

40

60

80

100

0 2 4 6 8 10

B

0

20

40

60

80

100


U/g

FW

D

0

20

40

60

80

100


Contro;lHDPEHDPEPLDPELDPEP

Fig. 11: Effect of polyethylene packages on PPO activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 7.14, B = 5.07, C = 10.64, D = 7.76


Formatted: Left

79

Table 13.1: Effect of polyethylene packing on PPO activity of “Surkh” loquat

Storage period – Weeks (W) Treatment (T) 0 2 4 6 8 10 Means*

Control 0.61n 12.14klm 51.80b 58.06ab 62.21a 42.40c 37.87A HDPE 0.61n 21.60hij 25.99ghi 31.81efg 37.74cde 52.77b 28.42B HDPEP 0.61n 6.12mn 16.59jk 27.53fgh 65.33a 30.53efg 24.45BC LDPE 0.61n 7.17lmn 33.96def 15.57jk 34.15def 41.74cd 22.20C LDPEP 0.61n 6.08mn 36.02cde 18.58ijk 14.03jkl 52.27b 21.26C

Mean** 0.61D 10.62C 32.87B 30.31B 42.69A 43.94A

Surkh (Year 1)

LSD T= 5.50 W= 3.193 TW=7.14


Control 0.84n 13.42k 61.73a 42.48def 50.33c 39.14fgh 34.66A HDPE 0.84n 6.66lm 45.04cde 45.74cde 55.44b 44.44cde 33.03A HDPEP 0.84n 8.53kl 41.70ef 25.90i 47.60cd 35.94gh 26.7B LDPE 0.84n 2.93mn 40.91efg 19.11j 55.72b 28.43i 24.66C LDPEP 0.84n 9.45kl 24.38ij 45.10cde 24.18ij 34.76h 23.12C

Mean** 0.84E 8.20D 42.75B 35.67C 46.66A 36.54C

Surkh (Year 2)

LSD T= 1.78 W= 2.26 TW=5.07

Table 13.2: Effect of polyethylene packing on PPO activity of “Sufaid” loquat


Control 0.52l 11.07l 52.36def 79.24a 53.68def 30.67j 37.92A HDPE 0.52l 7.33l 48.30d-g 73.84ab 57.61cd 24.87k 35.41AB HDPEP 0.52l 5.55l 42.52f-i 34.09h-k 44.85e-h 65.23bc 32.13BC LDPE 0.52l 6.43l 53.56def 48.37d-g 40.32ghi 28.04jk 29.54C LDPEP 0.52l 6.60l 37.68g-j 37.57g-j 54.94cde 38.75g-j 29.34C

Mean** 0.52E 7.39D 46.88B 54.62A 50.28AB 37.51C

Sufaid (Year 1)

LSD T= 4.05 W= 4.75 TW=10.64

Storage period – Weeks (W) Treatment

(T) 0 2 4 6 8 10 Means* Control 0.72l 11.86k 55.39de 51.56ef 76.18a 69.18ab 44.15A HDPE 0.72l 8.24kl 31.01ij 71.25ab 65.70bc 42.68gh 36.60B HDPEP 0.72l 8.50kl 33.13ij 45.30fg 51.38ef 56.90de 32.66BC LDPE 0.72l 7.94kl 45.44fg 60.26cd 49.52efg 25.48j 31.56C LDPEP 0.72l 4.64kl 33.78ij 26.68hj 36.42hi 33.24ij 22.58D

Mean** 0.72F 8.24E 39.75D 51.01B 55.84A 45.50C Sufaid (Y

ear 2)

LSD T= 4.14 W= 3.47 TW= 7.76


80

minimizes postharvest moisture loss. Packaging maintains a high humidity around the

fruit surface and reduces moisture loss whereas, refrigerated storage extends the shelf

life by slowing metabolic processes (Bryant, 2004). High oxygen levels in MAP and

controlled atmosphere conditions may cause inhibition of the PPO enzyme substrate

(Kader, 2002a). PPO catalyzes the oxidation of o-diphenols into o-quinones in the

presence of oxygen (Ding et al., 1998a) which is the first step in the polymerization of

phenolics to form o-quinones. In MAP, the gas exchange properties of packaging is used

to manipulate the atmosphere surrounding the fruit during storage. Polyethylene (PE),

polyvinyl chloride (PVC), polypropylene and polystyrene are the most effective barriers

which have very low rates of permeability to water vapor (Joyce and Patterson,1994).

Increase in PPO contents in bagged fruits of “Jiefangzhong” cv. of loquat during storage

has also been reported by Zheng et al. (2001). Our results also indicate that PPO activity

was increased in all treatments during the ten week storage period, however this increase

was less in both LDPE treatments as compared to control and HDPE treatments which

indicates that substrate inhibition of PPO was caused as indicated by Kader (2002b).

PPO is known to be closely related with browning index. In this study a strong positive

correlation r = 0.85 and 0.96 for Surkh while r =0.75 and 0.74 for Sufaid during the first

and second years respectively for PPO and browning index.

2.6.12. Effect on Total Phenolic Content

Total phenolics (TP) in the fruit of cv. “Surkh” loquat remained higher in both

non perforated packages (Table 12.1) while no significant difference was observed

among control and both perforated packages. HDPE and LDPE were statistically similar

Deleted: Appendix

81

and retained significantly higher TP content both the years. Highest retention in TP

content (28.39 mg 100-1 g) was recorded in LDPE during the first year while during the

second year HDPE had highest TP content (33.94 mg 100-1 g) as compared to 25.07 mg

100-1 g in control. During the tenth weeks in both years LDPE had the highest content

(20.53 and 28.47 mg 100-1 g) compared to 16.33 and 14.11 mg 100-1 g in control during

the same storage period.

In “Sufaid” cultivar, no significant difference was observed within the PE

packages, however, all packages were statistically superior than control during the first

year. In the second year, both non perforated packages differed significantly from rest of

the treatments. Control and both perforated packages had significantly lower TP content

than rest of the treatments. The pattern of decrease was similar to that observed in

“Surkh” cv. during the ten week storage (Fig. 12). At the end of tenth week storage,

HDPE, LDPE had higher TP content of 20.27 and 21.07 mg 100-1 g while control had a

TP content of 13.17 mg 100-1 g in the first year. In the second year HDPE had the highest

content (20.63 mg 100-1 g) compared to 13.17 mg 100-1 g) in control.

Phenolic compounds are bioactive substances and are synthesized as secondary

metabolites by all plants. They have many diverse functions such as nutrient uptake,

protein synthesis, enzyme activity and photosynthesis (Robbins, 2003). Phenolics have

an essential role in the defense system of fruits acting as filters to protect various cell

structures from the harmful effects of UV radiation. These are present generally as

flavonols in the skin of fruits (Hamauzu, 2006).These compounds impart vital sensory

82

A

0

10

20

30

40

50

0 2 4 6 8 10

mg/

100g

FW

C

0

10

20

30

40

50

0 2 4 6 8 10

B

0

10

20

30

40

50


mg/

100g

FW

D

0

10

20

30

40

50


Control

HDPE

HDPEP

LDPE

LDPEP

Fig. 12: Effect of polyethylene packaging on total phenolics in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 3.67, B = 4.18, C = 3.37, D = 3.67


83

Table 14.1: Effect of polyethylene packing on total phenolics of “Surkh” loquat


Control 36.40a 31.90bcd 24.13ghi 21.97hij 19.67jkl 16.33l 25.07B HDPE 36.40a 33.03abc 25.23fgh 20.27i-l 21.10h-k 19.67jkl 25.95AB HDPEP 36.40a 29.47cde 23.10hij 17.33kl 19.70jkl 19.50jkl 24.25B LDPE 36.40a 34.27ab 28.67def 27.43efg 23.03hij 20.53i-l 28.39A LDPEP 36.40a 30.33b-e 29.73cde 20.83ijk 22.60hij 17.43kl 26.22AB Mean** 36.40A 31.80B 26.17C 21.57D 21.22D 18.69E

Surkh (Year 1)

LSD T=2.62 W=1.64 TW=3.67


Control 44.83a 36.17c-f 31.90fg 24.13h-k 19.53klm 14.10n 28.44B HDPE 44.83a 39.80bc 37.73cde 33.33ef 26.00hij 21.93jkl 33.94A HDPEP 44.83a 34.43def 25.93hij 23.33ijk 19.83klm 16.37mn 27.46B LDPE 44.83a 38.20cd 34.10def 28.20cd 34.10def 28.47gh 31.95A LDPEP 44.83a 37.13cde 27.43hi 24.07h-k 18.50lmn 15.70mn 27.74B Mean** 44.83A 37.15B 31.42C 26.67D 22.01E 17.60F

Surkh (Year 2)

LSD T=3.17 W=1.87 TW=4.18

Table 14.2: Effect of polyethylene packing on total phenolics of “Sufaid” loquat


Control 36.23a 31.13b 26.13c 20.30fgh 17.70ghi 14.57i 24.34B HDPE 36.23a 35.60a 26.40c 24.80cde 21.53d-g 20.27fgh 27.47A HDPEP 36.23a 35.50a 25.00cd 21.67def 19.97fgh 16.67hi 25.84AB LDPE 36.23a 33.83ab 25.80c 24.73cde 21.73def 21.07efg 27.23A LDPEP 36.23a 31.20b 26.50c 23.10c-f 19.87fgh 17.73ghi 25.77AB Mean** 36.23A 33.45B 25.97C 22.92D 20.16E 18.06F

Sufaid (Year 1)

LSD T=2.62 W=1.50 TW=3.37


(T) 0 2 4 6 8 10 Means* Control 39.40a 30.30cd 24.13efg 19.67h-k 17.27jkl 13.17lm 23.99C HDPE 39.40a 37.63a 33.17bc 28.00de 25.07ef 20.63g-j 30.65A HDPEP 39.40a 30.20cd 22.90fgh 17.47-l 17.03jj-m 13.80lm 23.47C LDPE 39.40a 35.43ab 31.23cd 24.80efg 21.57f-i 17.07j-m 28.16AB LDPEP 39.40a 35.20ab 29.13cd 21.53f-i 16.30klm 12.93m 25.75BC Mean** 39.29A 33.75B 28.11C 22.29D 19.45E 15.52F

Sufaid (Year 2)

LSD T=3.05 W=1.68 TW=3.76


84

attributes in foods such as color, astringency, and bitterness along with other possible

nutritional properties.

Enzymatic browning is also the most important color reaction that affects fruits

and vegetables. The severity of browning is related to the amount of active enzyme

forms and the phenolic content of the fruit tissue (Robert et al., 2003). Generally the

amount of polyphenols in loquats is very high and about 60% of it is chlorogenic acid and

neochlorogenic acid in the ripe fruit (Ding et al., 1999). Total phenol content of fruits

stored in CA conditions have been reported to decrease during storage (Tian et al.,

2005). According to Hamauzu (2006) the phenolic change patterns vary after harvest and

during storage. Although elevated CO2 and reduced O2 in normal CA or MA conditions

appear to suppress the increase of phenolic content. Ding et al. (1998b) reported a

decline in total phenolic contents and increase in PPO activity in loquat over the eight

day storage period.

Our results indicate that PE packages efficiently abbreviated the decrease of TP

content of both varieties of loquat during storage as compared to control. Gonzalez et al.

(2004) observed an acute decrease in phenols of control treatment of pineapple slices

after cold storage. In this study, non perforated PE treatments proved to be more effective

than the perforated treatments. The decline in soluble phenolics toward the end of

storage may be as a result due to the collapse of the cellular structures (Toor and

Savage, 2006). Non perforated PE seem to retard the breakdown of these cellular

structures.

85

A

0

10

20

30

40

50

0 2 4 6 8 10

Brow

ning

Inde

x (%

)

C

0

10

20

30

40

50

0 2 4 6 8 10

B

0

10

20

30

40

50


Brow

ning

Inde

x (%

)

D

0

10

20

30

40

50

0 2 4 6 8 10


Contro;l

HDPE

HDPEP

LDPE

LDPEP

Fig. 13: Effect of polyethylene packaging on browning index in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 3.96, B = 3.74, C = 1.92, D = 2.07


86

2.6.13. Effect on Browning Index

Data pertaining to browning index (BI) of “Surkh” cultivar (Table 11.1), reveals

that control and HDPE had highest BI followed by both perforated packages

whereas LDPE had the lowest BI in both years. There was a gradual increase in the

browning index during the ten week storage period. Control and HDPE had the highest

BI in the tenth week as compared to rest of the treatments.

In “Sufaid” cv. also, control had maximum BI followed by HDPE (Table 11.2)

during both the years. HDPEP, LDPE and LDPEP had 4.20%, 6.31% and 8.50% BI

values in the first year, whereas during the second year, these treatments had 10.97%,

6.90%, 8.71% BI. During the entire storage period, BI increased gradually (Fig. 13).

Overall, control had a maximum BI of 31.3% and 40.87% by the end of tenth week in

both years, while lowest BI 9.63% and 13.97% was recorded in HDPEP and LDPE in

year one and year two. Internal browning, adherence of peel and flesh and tissue

lignification the primary causes of quality loss in loquat fruit after harvest (Ding et al.,

2002a). Tissue browning is a result of oxidative reactions of phenolic compounds which

results from collapse of compartmentalization in the cells when exposed to physical or

physiological stresses (Ding et al., 2006). The decay of loquat fruit is caused primarily

by an internal flesh browning followed by complete rotting. Higher gas permeable MAP

showed a lower incidence of decay at 20°C and 5°C, and fruit in 20-30µm-thick PE bags

could be stored for 8 weeks with acceptable quality and minimal risk of decay at 5 °C

(Ding et al., 2002b).

Deleted: Appendix

Deleted: Appendix

87

Table 15.1: Effect of polyethylene packing on browning index of “Surkh” loquat


Control 0.00m 4.26lm 17.37efg 27.73cd 30.83c 39.30ab 19.92A HDPE 0.00m 0.86m 17.63efg 25.60d 35.40b 40.73a 20.04A HDPEP 0.00m 1.40m 9.70jk 15.10fgh 17.37efg 21.43e 10.83B LDPE 0.00m 0.33m 7.06kl 10.67ijk 12.47hij 19.37ef 8.31C LDPEP 0.00m 1.66m 12.17hij 12.73hij 14.80ghi 21.10e 10.41B Mean** 0.00F 1.75E 21.35D 26.38C 29.80B 36.91A

Surkh (Year 1)

LSD T=1.61 W=1.41 TW=3.96


Control 0.00p 5.26no 18.10ghi 31.38c 37.06ab 40.53a 22.06A HDPE 0.00p 0.83p 17.53g-j 25.93de 28.00cd 35.27b 17.93B HDPEP 0.00p 0.96p 11.47kl 15.33h-k 18.90fgh 22.73ef 11.57C LDPE 0.00p 0.33p 6.86mn 11.20kl 12.80kl 19.67fg 8.47D LDPEP 0.00p 1.66op 10.50lm 13.83jkl 14.63i-l 22.60ef 10.54CD Mean** 0.00F 1.20E 9.5D 18.21C 22.19B 25.54A

Surkh (Year 2)

LSD T=2.45 W=0.92 TW=3.74

Table 15.2: Effect of polyethylene packing on browning index of “Sufaid” loquat


Control 0.00k 0.33k 8.30gh 15.77e 24.17b 31.30a 13.31A HDPE 0.00k 0.33k 9.73gh 14.77ef 17.90d 22.00c 10.79B HDPEP 0.00k 0.33k 2.40j 4.73i 8.13h 9.63gh 4.20E LDPE 0.00k 0.00k 4.76i 9.13gh 10.50g 13.50f 6.31D LDPEP 0.00k 0.33k 8.50gh 10.47g 13.77ef 18.43d 8.50C Mean** 0.00E 0.26E 6.74D 10.97C 14.89B 18.97A

Sufaid (Year 1)

LSD T=1.61 W=0.88 TW=1.92


(T) 0 2 4 6 8 10 Means* Control 0.00m 4.33l 10.47jk 30.74b 39.33a 40.87a 20.96A HDPE 0.00m 0.33m 13.23hi 24.40d 28.37c 31.63b 16.33B HDPEP 0.00m 0.33m 9.50jk 15.63g 18.03f 22.30e 10.97C LDPE 0.00m 0.33m 6.06l 9.53jk 11.53ij 13.97gh 6.90E LDPEP 0.00m 0.66m 8.23k 10.77j 13.70ghi 18.93f 8.71D Mean** 0.00F 1.20E 9.50D 18.21C 22.19B 25.54A

Sufaid (Year 2)

LSD T=0.04 W=0.92 TW=2.07


88

Internal browning and brown surface spotting in loquat fruit stored in perforated

or higher permeance PE bags have been known to develop during prolonged or high CO2

storage (Ding et al.,1999). Ding et al. (1997) reported that packing loquat fruit in

polyethylene film bags of different thickness (20, 30 and 50 µm) developed internal

browning and the incidence was higher in the thicker bags. Loquat fruit (cv. ‘Wuxing’)

packaged in polyethylene (PE) bags, showed a notably lower decay index at 1°C than that

at 6 °C (Ding et al. 2006).

Our results reveal that significantly lower BI was attained in perforated

and low density PE, whereas HDPE had significantly higher BI. This may be because

LDPE and perforated packages had a greater gas permeability which is in accordance

with the findings of Ding et al. (2002).

2.6.14. Effect on Relative Electrical Conductivity

Relative electrical conductivity (REC) in fruit of “Surkh” cultivar (Table 16.1)

reveals a highly significant effect of packaging treatments. Highest REC (52.67% and

52.43%) was recorded in control during both years, which differed significantly from

rest of the treatments. No significant difference was recorded within different packaging

treatments during the first year, however during the second year, LDPE had a significant

difference from rest of the packaging treatments (Fig. 14). Overall, during both years of

study, REC increased with the passage of time in all treatments. Control had the highest

EC values (76.67% and 74.97%) in the tenth week during both years.

Deleted: Appendix

89

A

0

20

40

60

80

100

0 2 4 6 8 10

Rel

ativ

e El

ectri

cal

Con

duct

ivity

(%)

C

0

20

40

60

80

100

0 2 4 6 8 10

B

0

20

40

60

80

100


Rel

ativ

e El

ectri

cal

Con

duct

ivity

(%)

D

0

20

40

60

80

100

0 2 4 6 8 10Storage period (weeks)


Fig. 14: Effect of polyethylene packaging on relative electrical conductivity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 5.08, B = 4.19, C = 5.47, D = 6.07


90

Table 16.1: Effect of polyethylene packing on relative electrical conductivity of “Surkh” loquat


(T) 0 2 4 6 8 10 Means* Control 29.83h 44.43efg 50.20cde 57.57b 57.33b 76.67a 52.67A HDPE 29.83h 45.13efg 47.03def 51.37cd 41.87fg 45.10efg 43.39B HDPEP 29.83h 40.60g 41.00fg 43.20fg 45.27efg 54.77bc 42.44B LDPE 29.83h 40.60g 50.07fg 43.80fg 40.63g 44.90efg 41.64B LDPEP 29.83h 42.20fg 44.60efg 44.43efg 43.13fg 43.03fg 41.21B Mean** 29.83E 42.59D 46.58BC 48.07B 45.65C 52.89A

Surkh (Year 1)

LSD T=2.03 W=2.27 TW=5.08


(T) 0 2 4 6 8 10 Means* Control 25.70k 45.63def 51.27c 56.63b 60.37b 74.97a 52.43A HDPE 25.70k 33.47j 45.20def 44.73d-h 42.90f-i 43.03f-i 39.17C HDPEP 25.70k 34.17j 42.83f-i 38.60i 44.60d-h 49.33cd 39.21C LDPE 25.70k 44.70d-h 44.90d-g 44.23e-h 47.03c-f 43.80fgh 41.73B LDPEP 25.70k 32.27j 46.97c-f 49.13cde 39.83hi 40.07ghi 38.99C Mean** 25.70D 38.05C 46.23B 46.67B 46.95B 50.24A

Surkh (Year 2)

LSD T=2.52 W=1.87 TW=4.19

Table 16.2: Effect of polyethylene packing on relative electrical conductivity of “Sufaid”

loquat


Control 30.30j 40.23ghi 48.97b-e 52.43bc 54.87b 77.13a 50.66A HDPE 30.30j 43.13e-i 46.83c-f 46.60c-f 44.23e-i 44.83d-h 42.66BC HDPEP 30.30j 37.73i 44.10e-i 50.77bcd 45.37d-h 53.53b 43.63B LDPE 30.30j 38.07i 45.20d-h 41.63f-i 40.50f-i 40.07ghi 39.29C LDPEP 30.30j 43.47e-i 52.17bc 53.37b 39.30hi 41.87f-i 43.41B Mean** 30.30E 40.53D 47.45B 48.96B 44.85C 51.49A

Sufaid (Year 1)

LSD T=3.40 W=2.44 TW=5.47


(T) 0 2 4 6 8 10 Means* Control 26.63l 43.23d-i 49.57cde 54.80bc 59.30b 75.10a 51.44A HDPE 26.63l 32.57kl 34.83jk 41.27g-j 42.33f-i 43.13d-i 36.79C HDPEP 26.63l 37.30h-k 36.33ijk 43.93d-h 42.57e-i 47.80d-g 39.09BC LDPE 26.63l 33.60k 36.37ijk 45.33d-g 38.10h-k 42.23ghi 37.04C LDPEP 26.63l 35.13jk 46.77d-g 50.23cd 49.40c-f 41.57g-j 41.62B Mean** 26.63E 36.37D 40.77C 47.11B 46.34B 49.97A

Sufaid (Year 2)

LSD T=3.07 W=2.71 TW=6.07


Formatted

91

Relative electrical conductivity in all packaging treatments differed significantly

from control in “Sufaid” cultivar (Table 16.2), which had the highest REC value

(50.66% and 51.44%) during both years of the study. Both perforated and non perforated

packages were statistically similar during both years. REC increased during the ten week

storage in all treatments. Highest REC values of 77.13% and 75.10 % were recorded in

control during the tenth week during both years.

Relative electrical conductivity is thought to be an index to evaluate the integrity

of the cell membrane (Whitlow et al., 1992). During the ripening and senescing of loquat,

leakage of ions increases from the tissues of the skin (Zheng and Xi, 1999; Lin et al.,

1999; Zheng et al., 2000a ; Cai et al., 2006c) which may be caused by the attack of

reactive oxygen species (ROS), such as O2-, OH- and H2O2 (Cai et al., 2006a; Tian et al.,

2007). The prime targets of free radical reactions are unsaturated bonds in membrane

phospholipids resulting in loss of membrane fluidity and potential cellular lysis (Opara

and Rockway, 2006). Membranes and lipid are in particular vulnerable to oxidation and

peroxidative reactions caused by free radicals. Peroxidation of lipids is generally caused

by free radicals, which cause cellular injury by inactivating membrane enzymes and

receptors, depolymerising polysaccharide, cross-linking and fragmenting protein. As a

consequence, membrane fluidity and structure collapse and normal cell function ceases

(Rahaman, 2003; Ng et al., 2005).

This study shows that REC increased both in control and packages treatments as

the fruit senesce, however, rate of increase was greater in control suggesting that

packages had a positive effect on REC. A rise in electric conductivity of flesh tissue in

Deleted: Appendix

92

loquat fruit at both room and low storage temperature has been reported by Cai et al.

(2006c) and in bayberry by Xi et al. (1994) and Myrica et al. (2005). Storage at 5 °C in

modified atmosphere packaging retained the quality in some cultivars of loquat for 2

months (Ding et al., 2002). The REC data show a rise in membrane leakage as the fruit

senesces and the inhibitory effects of different packages on fruit changes as compared to

non packaged control. Increased REC during the tenth week in control of both cultivars

during both years indicates greater membrane breakdown (Fig. 37), which may be

explained by the fact that plasma membrane of the cell might have become unstable

during storage and as a result lead to electrolyte leakage (Feng et al., 2005). Cai et al.

(2006c) reported that highly significant correlation existed between browning index and

cell membrane permeability. Our data on tissue browning also support an increase in cell

membrane permeability with senescence as indicated by Pearson linear correlation

coefficients (P < 0.05), r = 0.72 and 0.78 for Surkh and r =0.73 and 0.69 for Sufaid

during both years respectively.

2.7 CONCLUSION

Both non perforated polyethylene packages retained maximum TA, AA, reducing

sugars, non reducing sugars, total sugars, BI, SOD and CAT activity whereas TSS, POD

activity and weight loss was low in both cultivars for 6-7 weeks as compared to

perforated polyethylene packages

Deleted:

93

Chapter 3

EFFECT OF CALCIUM CHLORIDE TREATMENTS ON STORAGE LIFE OF

LOQUAT

3.1 ABSTRACT

In order to study the effectiveness of calcium chloride treatments on postharvest

quality and storage behavior of loquat fruit, three dipping treatments with 1%, 2% and

3% calcium chloride were applied on two local cultivars (Surkh and Sufaid) of loquat

fruit which were harvested at mature ripe stage in the month of April. The fruit were

sorted , washed and clipped on the same day. Dipping treatments were applied for two

minutes and fruit stored in soft board cartons at 4˚C in a cold store, for a ten week

period. Changes in weight loss, firmness, total soluble solids, browning index, ascorbic

acid, titratable acidity, electrolyte leakage, total phenolics, polyphenol oxidase,

superoxidase dismutase, peroxidase, catalase and total antioxidants were studied. 1 %

CaCl2 did not affect quality parameters of the fruit compared to control treatment. 2%

CaCl2 had high firmness, Radical scavenging activity (RSA) , SOD, CAT activity and

low Polyphenol oxidase (PPO), POD activity and electrical conductivity (EC) while in

addition to the above parameters 3% CaCl2 retained maximum firmness, TSS, Total

Phenolics (TP) content, reducing, non reducing and total sugars, lowest BI and weight

loss up to 4-5 weeks in both cultivars.

94

3.2 INTRODUCTION

Postharvest quality of fruits are influenced by several pre and post harvest factors.

Calcium (Ca2+) has been extensively reviewed as both an essential element and its

potential role in maintaining postharvest quality of fruit and vegetable crops (Kirkby and

Pilbeam, 1984; Shear, 1975; Bangarth, 1979). Calcium (Ca2+) has an important role in

postharvest quality, because of its role in plant metabolism and membrane stability

(Kirkby and Pilbeam, 1984) by contributing to the linkages between pectic substances

within the cell-wall (Demarty et al., 1984).

The essentiality of this element has been extensively reviewed in the areas of

maintaining cell-walls and membrane integrity, and its role in reducing the rate of

senescence and softening (Demarty et al., 1984; Ferguson, 1984; Kirkby and Pilbeam,

1984; Marschner, 1995; Poovaiah et al., 1988., Esmel, 2005). It is accepted that the

presence of Ca2+ ions increases the cohesion of cell-walls (Demarty et al., 1984).

Calcium is also involved in reducing the rate of senescence and fruit ripening (Ferguson,

1984).

In order to expand the fresh produce market, exploration of possible methods to

extend storage-life perishable commodities is required. The use of additional Ca2+

application to commodities has been viewed as the potential non-fungicidal, senescence

delaying treatment (Esmel, 2005). Postharvest applications allow Ca2+ solutions to have

direct contact with the surface of the fruit Conway et al. (1992).

Formatted

Deleted: a

95

Calcium has an important role in the ripening process (Ferguson et al., 1995).

Reduction in quality at some point is expected when the level of Ca2+ drops below the

critical concentration for development. The object of the study was to see the

effectiveness of different Ca2+ treatments on the postharvest physiology and quality of

loquat fruit.


3.3.1 Postharvest Physiology

Postharvest physiology is the study of living, respiring plant tissue that has been

separated from the parent plant (Shewfelt, 1986). The quality and postharvest life of

fruits and vegetables depends on the biochemical processes taking place after harvest.

(Sanchez-Mata et al., 2003). The quality and postharvest life of horticultural

commodities is influenced by cultural and postharvest handling practices. (Armitage and

Laushman, 2003; Dole and Wilkins, 2005).

After harvest, metabolic reactions are continuously performed by the commodity

to maintain its physiological system causing a reduction in its quality and shelf-life.

Respiration generates heat which raises temperature, affecting metabolic processes and

accelerating decay (Holdsworth,1988). Decreasing temperature lowers metabolism,

which prolonging shelf-life. Extension in postharvest life is associated with reduced

respiration at low storage temperature.

In general, fruits and vegetables decay easily, and if not handled properly during

harvesting and transportation they deteriorate and cannot be consumed. The losses

Formatted: No underline

Deleted: ¶

96

occurring during production in developing countries cannot be estimated accurately, but

it is believed by some authorities that they may reach upto as much as fifty percent of the

total production. Reducing these losses can be very significance to both the growers

and consumers (Maria, 2007).

Greater significance to the consumer are the other changes that occur during

ripening, including softening, color changes, sugar content, flavor, and aroma. As the

tissues of stored fruits and vegetables are still alive, they require environmental

conditions which will lead to retarded maturation, so that the appearance, color, flavor,

texture, aroma and other qualities for which they are prized, will be preserved. It is not

possible to improve the quality of a produce after harvest, but it is possible to reduce the

rate of quality loss. This is the key concept in horticultural produce storage.

Maintenance of quality is highly dependent on the development of adequate

postharvest technology. Research in fruit physiology and postharvest technology are

dependent on each other for storage attempts to be successful. Studies on the physiology

of fruit preservation must be carried out on an experimental basis because there are no

guidelines that can precisely identify optimum storage conditions for a single product.

This is because the relative rates of the biochemical and physiological changes occurring

are subject to several factors. The importance of each change and the rate at which it

occurs may differ between cultivars, maturity stage and temperature or differ according

to soil and climatic conditions in which fruits are grown (Maria, 2007).

Fernando et al. (2004) states that the postharvest life of horticultural products is

generally assessed on the basis of their visual appearance such as color, freshness, degree

97

of spoilage or physiological disorders and texture which include firmness, crispness and

juiciness. The overall condition of quality such as firmness and nutrient content, is

influenced mainly by temperature due to the alteration in rate of respiration. Careful

handling can reduce the damage done by sharp implements, use of browning inhibitors,

proper packaging and use of modified atmospheres (Monica et al., 2003; Ahvenainen,

1996; Abbott, 1999; Agar et al., 1999; Watada and Qi, 1999)

3.3.2 Dipping Treatments

Surface treatments have been known to retard the decay process in fruit tissues,

stabilize the fruit surface and prevents degradation which adversely affect the product

quality. Dipping treatments are useful as they wash away the enzymes and substrates

secreted from damaged cells during harvesting and handling of the product surface. High

dipping temperatures of 60°C improves the beneficial effect of the dips as compared

lower dipping temperatures (40 °C and 20 °C) probably because diffusion is stimulated

elevated temperatures. In fruits where browning is caused mainly by polyphenol oxidase,

surface dips are normally done at temperatures not exceeding 20 °C (Robert et al.,

2003). Acids, such as citric, malic, or phosphoric acid, mainly inhibit PPO activity by

lowering the pH and / or by chelating copper in the produce (Richardson and Hyslop,

1985).

3.3.3 Calcium Chloride (CaCl2 )

Fruit texture refers to the “structural and mechanical properties of a food and their

sensory perception in the hand or mouth” (Abbott and Harker, 2003; Sams, 1999). Fruit

98

firmness pertains to the strength of the fruit tissue to sustain a force and is a part of the

sensory perception of texture (Esmel, 2005). Calcium has received attention because of

its effects in delaying senescence, mold development and effecting physiological

disorders in fruits and vegetables (Suutarinen, 2002). Calcium and its salts are

extensively used to control softening of many processed fruits. Ultrastructural studies of

fresh cut apple have shown that infiltrated calcium binds with the cell walls and middle

lamellae where major changes in firmness are likely to occur (Glenn and Poovaiah,

1990). Calcium application at both pre or postharvest stage may slow down senescence

in commercial and retail storage of fruit with no harmful effect on consumer acceptance

(Lester and Grusak, 2004). Calcium, as a component of the cell wall, plays an essential

role in constituting cross-bridges which strengthens the cell wall and is considered as

the last obstacle prior to separation of the cells (Fry, 2004). Calcium applied exogenously

strengthens cell walls of plants thereby protecting them from cell wall degrading

enzymes (White and Broadley, 2003).

Studies on leaf senescence and fruit ripening have indicated that the rate of

senescence often depends on the calcium status of the tissue and that by increasing

calcium levels, various parameters of senescence such as respiration, protein, chlorophyll

content and membrane fluidity are altered (Poovaiah,1986). The impairment of the cell

membranes may be implied as a loss of membrane permeability which in turn can be

measured as increased solute leakage from the cell (Nan, 2007). Research in the field of

postharvest physiology have shown that Ca may be involved in governing membrane

stability and senescence of plant cells (Torre et al., 1999; Rubinstein, 2000). It is believed

99

that extra cellular Ca concentrations may be related in repressing senescence (Ferguson,

1984; Leshem, 1992).

Calcium has proved to retain humidity, enhance texture and structure of the

polymers of cell walls during ripening or processing of fruits and vegetables by

establishing cross linkages between pectin chains and free carboxyl groups (Roy et al.,

1994). Rosen and Kader (1989) indicated that 1% CaCl2 dip alongwith 0.5% O2

atmosphere decreased softening and browning rates in pear slices. 1–5% calcium

chloride dips have been known to improve firmness in cantaloupe during storage at 5°C,

with 1 minute dips showing the same effect as 5 minutes dips (Guzman et al., 1999)

while fresh-cut kiwifruit slices had a shelf-life of 9-12 days when treated with 1% CaCl2

or 2% Ca lactate, and stored at 0-2°C and >90% relative humidity in an C2H4-free

atmosphere (Agar et al., 1999). CaCl2 avoided softening and maintained the structures of

cell walls through cross-linking the pectic acid in the cell wall (Gunes et al., 2001). Ca2+

suppressed senescence by strenghtening membrane integrity (Gekas et al., 2002). 1 %

calcium chloride solution delayed fruit ripening , improved resistance to fungal attack

and maintained structural integrity of cell walls of strawberry during a 10 day storage

period at 3°C (Lara et al., 2004). Softening was delayed and storage life was increased

by 10–12 weeks in Kiwi fruits stored at 0°C for up to 42 weeks by application of 1%

calcium chloride compared with untreated fruit (Dimitrios and Pavlina, 2005).

3.3.4 Electrolyte Leakage

Cell membranes regulate the movement of nutrient ions and other metabolites in

and out of the cells and preserve cell compartments for retention of water. An organism’s

100

survival is dependent on the preservation of the structure and function of cellular

membranes (Rubinstein, 2000). Cell membrane desolation has an essential role in

senescence. Many physiological changes occur during the disruption of the cell

membrane which eventually lead to senescence. These changes include an increase in

ethylene production and abscissic acid content, lower uptake of sucrose, and decline in

activity of ATPase (Itzhaki et al., 1990). A gradual disruption of membrane integrity loss

of compartmentation of cytoplasmic organelles and an increase in permeability of the

plasma lemma are accepted phenomena leading to progressive aging and senescence of

plant tissues (Thompson, 1988).

Water content inside the cell and the solute concentration of this intracellular

water is responsible for maintaining the water potential (Halevy and Mayak, 1981). Cell

membrane disruption causes leakage of solutes from the cells and adversely affect water

balance inside and outside the cell (Halevy and Mayak, 1981; Borochov and Woodson,

1989; Torre et al., 1999). Literature on senescence proves that deterioration of cell

membrane has a vital role in this process (Adam et al., 1983; Borochov and Woodson,

1989; Itzhaki et al., 1990). The disruption of cell membranes can be stated as a loss of

membrane permeability and measured as the increase in solute leakage from the cell.

Membrane fluidity and microviscosity regulates the changes in membrane permeability

(Borochov and Woodson, 1989; Itzhaki et al., 1990; Torre et al., 1999; Rubinstein,

2000). Many biochemical and molecular changes in cell membranes cause the loss of its

structure and function (Rubinstein, 2000; Paliyath and Droilldard, 1992).

101

Electrolyte leakage is an indirect measure of damage done to plant cell

membranes (Xuetong and Kimberly, 2005). It can serve as an effective physical

maturity index and also a suitable index of storage quality, moreover it is very

convenient (Montoya et al., 1994).

Electrolytes are bound inside the membranes of plant cells. These membranes are

very sensitive to environmental stresses such as chilling and freezing conditions. Cold

temperatures decreases enzyme activity, changes metabolism, and declines the

photosynthetic capability of plant tissues (Dubey, 1997). Unstressed, undamaged plant

cells maintain electrolytes within the membrane. High conductivity indicates higher

leakage of intracellular ions and, therefore, damage to membranes (Ade-Omowaya et

al.,2003). Injured and uninjured tissues electrolyte leakage may be a good indicator for

hardiness or damage of cells under stress (McNabb and Takahashi, 2000). In plant

membranes, these changes are often associated with a rise in permeability and decline in

integrity (Campos et al., 2003). It is likely that plasma membrane of the cell become

unstable during storage and as a result lead to excessive electrolyte leakage (Feng et al.,

2005).


Fruit of two loquat cultivars were clipped and washed with distilled water to

remove any dirt as described in section 2.4. and dipped for two minutes in the following

concentrations of calcium chloride (CaCl2) solution:

102

i) 0% CaCl2 (Distilled water )

ii) 1 % CaCl2 solution

iii) 2 % CaCl2 solution

iv) 3 % CaCl2 solution

Each treatment comprising of one hundred fruit was replicated three times for

each concentration. Fruit were placed in corrugated soft board cartons in three layers

separated by soft board sheets and stored at 4 °C in the cold store for ten weeks.

Sampling and analysis was done as described in section 2.4. Randomly selected

ten fruit were analysed on day one and then at seven days intervals from each

replication. Browning index was noted and then fruit was hand peeled, cut into small

pieces and samples ranging from 70 – 80g pulp was frozen in liquid nitrogen and stored

at -20 °C until further analysis. Total soluble solids, firmness, sugar content, Vitamin C

content were analysed immediately after sampling.

Data on the following parameters as explained in section 2.4 was recorded to evaluate the effect of different treatments.

• Weight Loss

• Fruit Firmness

• Total Soluble Solid

• Sugars

Reducing sugars

Total Sugars

Non- Reducing Sugars

103

• Titratable Acidity

• Total Soluble Proteins

• Superoxide Dismutase (SOD) Assay

• Catalase (CAT) Assay

• Peroxidase (POD) Assay

• Ascorbic Acid Content (Vitamin C)

• Radical Scavenging Activity

• Polyphenol Oxidase (PPO) Assay

• Total Phenolic Compounds

• Browning Index

• Relative Electrical Conductivity


The experiment layout and analysis was done as described in section 2.5.

Deleted: EXPERIMENTAL DESIGN AND

104


3.6.1 Effect on Weight Loss

Maximum weight losses occurred in control and 1% CaCl2 in “Surkh” cv. of

loquat (Table 17.1) while lowest loss was recorded in 3% CaCl2 (2.57% and 3.13%)

during both years. Weight loss was highest in the sixth and eight weeks. During the

fourth week, 1% and 2 % CaCl2 had 4.34% and 4.43% loss, while highest loss (6.15%)

occurred in control during the sixth week. During the second year, highest losses (4% ,

3.32% and 3.30%) was recorded in control, 1% and 2% CaCl2 which were statistically

similar (Fig. 15). Maximum losses (5.25%) occurred during the sixth week. Highest

losses (8.61% and 5.97% were recorded during the sixth and eight week in control.

No significant effect of CaCl2 treatments were observed on weight loss in

“Sufaid” cv. of loquat during the first year (Table 17.2), however all three concentration

differed significantly from control which had the highest weight loss (4.07%). Weight

loss was high during the fourth and sixth weeks. Maximum loss in weight (8.61%) was

recorded during the sixth week in control. A similar trend was observed during the second

year. Control had maximum weight loss 4.28%. The lowest loss (1.92%) was recorded in

3% CaCl2 followed by 2.65% and 2.59% in 1% and 2% CaCl2 which were statistically

similar (P =0.05). Highest losses in weight (4.13%) was recorded during the fourth week

in all treatments. Maximum loss in weight (6.19% and 6.32%) was recorded during the

fourth and sixth week in control.

Calcium application have known to be effective in terms of membrane

functionality and integrity maintenance, with lesser losses of phospholipids and proteins

Deleted: Appendix

Deleted: Appendix

105

A

0

2

4

6

8

0 2 4 6 8 10

Wei

ght L

oss

(%)

C

0

2

4

6

8

0 2 4 6 8 10

B

0

2

4

6

8

0 2 4 6 8 10

Storage pereiod (w eeks)

Wei

ght L

oss

(%)

D

0

2

4

6

8

0 2 4 6 8 10Storagre period (w eeks)

Water Dip

CaCl 1%

CaCl 2%

CaCl 3%

Fig. 15: Effect of calcium chloride on weight loss in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.30, B = 1.05, C = 0.42, D = 1.22

106

Table 17.1: Effect of calcium chloride on weight loss percentage of “Surkh” loquat

Storage Period – weeks (W) Treatment (T) 0 2 4 6 8 10

Means

Water dip 0.00i 2.28h 3.01fg 6.15a 4.96b 2.97fg 3.23A CaCl2 1% 0.00i 2.83g 4.34cd 4.41c 3.95d 2.36h 2.98AB CaCl2l 2% 0.00i 3.29ef 4.43dcd 3.03fg 3.13efg 2.33h 2.70BC CaCl2l 3% 0.00i 2.32h 3.55efg 3.22efg 4.24cd 2.12h 2.57C

Mean* 0.00E 2.68C 3.81B 4.21A 4.07A 2.44D

Surkh (Year 1)

LSD T = 0.29 W = 0.87 TW = 0.30


Means

Water dip 0.00j 2.57hi 3.37f-i 8.61a 5.97b 3.46e-i 4.00A CaCl2 1% 0.00j 4.55c-f 5.50bc 3.70d-h 3.74d-h 2.43i 3.32AB CaCl2l 2% 0.00j 2.66hi 4.74cd 4.91bcd 4.51c-f 2.98ghi 3.30AB CaCl2l 3% 0.00j 3.42f-i 4.68cde 3.77d-h 4.10d-g 2.84hi 3.13B

Mean* 0.00D 3.30C 4.57B 5.25A 4.58B 2.93C

Surkh (Year 2)

LSD T = 0.78 W = 0.52 TW = 1.05 Table 17.2: Effect of calcium chloride on weight loss percentage of “Sufaid” loquat


Means

Water dip 0.00j 2.92def 5.64b 6.14a 3.95c 5.76ab 4.07A CaCl2 1% 0.00j 2.28g 2.84def 3.05de 2.56fg 1.03i 1.96B CaCl2l 2% 0.00j 2.36g 2.34g 2.62efg 3.12d 1.36hi 1.96B CaCl2l 3% 0.00j 1.63h 3.23d 2.24g 2.32g 1.25hi 1.78B

Mean* 0.00D 2.30C 3.51A 3.51A 2.99B 2.35C

Sufaid(Year 1)

LSD T = 0.18 W = 0.21 TW = 0.42


Means

Water dip 0.00h 3.25bcd 6.19a 6.32a 3.76bc 6.17a 4.28A CaCl2 1% 0.00h 3.98h 4.04b 3.06b-f 3.12b-e 1.73efg 2.65B CaCl2l 2% 0.00h 3.72bc 2.73b-g 2.81b-g 3.82bc 2.49c-g 2.59BC CaCl2l 3% 0.00h 1.57g 3.55bcd 2.53c-g 2.16d-g 1.69fg 1.92C

Mean* 0.00C 3.13B 4.13A 3.68AB 3.21B 3.02B

Sufaid(Year 2)

LSD T = 0.67 W = 0.61 TW = 1.22 *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)

107

and lower ion leakage which may the reason for the lower weight loss found in calcium

treated fruit (Lester and Grusak, 1999). Mahajan and Dhatt (2004) reported that pear fruit

treated with CaCl2 proved to be most effective in reducing weight loss as compared to

non treated fruit during a 75 days storage period. Mahmud et al., (2008) also stated that

postharvest dipping with different concentrations of CaCl2 prolonged storage life and

reduced weight loss in papaya probably due to its effect on inhibition of ripening and

senescence and loss of fruit firmness. Our results reveal that weight losses were greater

in non treated fruits, whereas calcium treated fruits had lesser weight losses during

storage as compared to fruit kept in open. Thus, calcium might have delayed senescence

and rate of respiration and transpiration. Significant difference in weight losses were

noted in Sufaid variety treated by different CaCl2 concentrations as compared with

control. The differences in weight loss between the two varieties could be due to

differences in the water vapor permeability for two cultivars. Differences in weight loss

between cultivars of red raspberry subjected to different controlled atmosphere treatments

has been reported by Haffner et al., (2002).


Maximum firmness in “Surkh” cultivar (Table 18.1) was recorded in 2%

& 3% CaCl2 during the both years as compared to control. 1% CaCl2 retained less

firmness (1.11 kgf) as compared to other concentrations of CaCl2 during the first year

while all no significant difference was observed with packages treatments during the

second year. Storage period means show that firmness gradually increased during the

entire storage period in both years (Fig. 16).

Deleted: Appendix

108

A

0

1

2

0 2 4 6 8 10

Firm

ness

(kgf

)

C

0

1

2

0 2 4 6 8 10

B

0

1

2

0 2 4 6 8 10Storage pereiod (w eeks)

Firm

ness

(kgf

)

D

0

1

2

0 2 4 6 8 10

Storagre period (w eeks)

Water Dip

CaCl 1%

CaCl 2%

CaCl 3%

Fig. 16: Effect of calcium chloride agents on firmness in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.06, B = 0.08, C = 0.07, D = 0.06

109

Table 18.1: Effect of calcium chloride on firmness of “Surkh” loquat

Table 18.2: Effect of calcium chloride on firmness of “Sufaid” loquat


Water dip 0.76gh 0.60i 0.96f 1.13b-f 1.0ef 1.26bc 0.95C CaCl 1% 0.76gh 1.03ef 1.26bc 1.10c-f 1.06def 0.80g 1.00B CaCl 2% 0.76gh 0.63hi 1.06def 1.30b 1.13b-f 1.23bcd 1.02B CaCl 3% 0.76gh 1.06def 1.16b-e 1.23bcd 1.53a 1.53a 1.21A

Mean** 0.76C 0.83C 1.17B 1.19AB 1.18AB 1.20A

Sufaid(Year 1)

LSD T= 0.03 W= 0.14 TW= 0.07


Water dip 0.83l 1.13ghi 1.33cde 1.16cde 1.13fgh 0.90kli 1.08B CaCl 1% 0.83l 0.66m 1.0ijk 1.1hij 1.16fgh 1.3def 1.01B CaCl 2% 0.83l 1.10hii 1.2e-h 1.26efg 1.43bcd 1.56ab 1.23A CaCl 3% 0.83l 0.96jkl 1.1hij 1.33cde 1.46bc 1.66a 1.22A

Mean** 0.83D 0.96C 1.15B 1.21B 1.30A 1.35A Sufaid(Y

ear 2) LSD T= 0.11 W= 0.12 TW= 0.06

*, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)


Water dip 0.66i 0.7 1.00h 1.16efg 1.16efg 1.36cd 1.01C CaCl 1% 0.66i 0.96h 1.33cd 1.30cde 1.33cd 1.06gh 1.11B CaCl 2% 0.66i 1.06gh 1.23def 1.40bc 1.43abc 1.33cd 1.18A CaCl 3% 0.66i 1.03gh 1.10fgh 1.33cd 1.56a 1.53ab 1.20A

Mean** 0.66E 0.94D 1.16C 1.30B 1.37A 1.32AB

Surkh (Year 1)

LSD T= 0.05 W= 0.13 TW= 0.06


Water dip 0.73h 0.76h 1.03g 1.20d-g 1.20d-g 1.36cd 1.05B CaCl 1% 0.73h 1.06g 1.46aabc 1.40bc 1.36cd 1.13efg 1.19A CaCl 2% 0.73h 1.10fg 1.26c-f 1.43abc 1.46abc 1.33cd 1.22A CaCl 3% 0.73h 1.06g 1.16d-g 1.30cde 1.60a 1.56ab 1.23A

Mean** 0.73D 1.00C 1.23B 1.33A 1.40A 1.35A

Surkh (Year 2)

LSD T= 0.08 W= 0.17 TW= 0.08

110

Maximum firmness was recorded in 3% CaCl2 during eight and tenth weeks of both

years.

In “Sufaid” cultivar, 3% CaCl2 had maximum firmness during both years. No

significant difference was observed in 1% and 2% CaCl2 during the first year, while 2%

and 3% CaCl2 were statistically similar with values of 1.23 and 1.22 kgf as compared to

1.08 kgf in control the next year . Treating loquat with 1% CaCl2 was statistically similar

with control. Firmness increased in both cultivars during storage in both years.

Firmness of loquat has been known to increase during ripening and senescence,

possibly due to tissue lignification as reported by Cai et al. (2006d). Application of

calcium chloride is used extensively in fruits as it delays ripening and senescence, by

decreasing or preventing cell wall dissolution Lara et al. (2004). White and Broadly

(2003) reported that cross linking of pectic polymers is facilitated by calcium

accumulation in the cell wall which enhanced cell wall strength cohesion of cells. In the

present study firmness increased in all treatments as compared to day one. Loquat fruit

treated with different CaCl2 concentrations had higher firmness values as compared to

control. These results are in accordance with those reported by Shuiliang et al. (2002)

that postharvest dips with CaCl2 maintained firmness and eating quality of loquat.

3.6.3 Effect on Total Soluble Solids

Data pertaining to effect of calcium chloride (CaCl2) on TSS depicted in Appendices 19.1

and 19.2, shows that 3% CaCl2 had maximum TSS (13.1 ○Brix and 13.5 ○Brix)

followed by 2% CaCl2 with values of 12.4 ○Brix and 12.3○Brix during both years in

Deleted: period in both years (Fig. 16).

111

A

8

12

16

0 2 4 6 8 10

TSS

(Brix

%)

C

8

12

16

0 2 4 6 8 10

B

8

12

16

0 2 4 6 8 10


TSS

(Brix

)

D

8

12

16

0 2 4 6 8 10



Fig. 17: Effect of calcium chloride on total soluble solids in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.66, B = 0.66, C = 0.55, D = 0.65

112

Table 19.1: Effect of calcium chloride on total soluble solids of “Surkh” loquat


Water dip 12.07efgh 11.7fghi 11.5ghi 11.43hi 11.23i 10.50j 11.41D CaCl 1% 12.07efgh 12.43c-f 12.37c-f 12.07e-h 11.97e-i 12.23d-g 12.19C CaCl 2% 12.07efgh 12.37c-f 12.73cde 12.93bcd 12.70cde 12.17d-h 12.49B CaCl 3% 12.07efgh 13.63ab 13.60ab 14.27a 13.07bc 11.97e-i 13.10A

Mean** 12.07C 12.53AB 12.55AB 12.68A 12.24BC 11.72D

Surkh (Year 1)

LSD T= 0.14 W= 0.33 TW= 0.66


(T) 0 2 4 6 8 10 Means* Water dip 12.87bc 11.63efgh 11.47fgh 11.20ghi 11.07hi 10.67i 11.48C CaCl 1% 12.87bc 12.40cde 12.37cde 12.10cdef 11.57fgh 11.0d-h 12.18B CaCl 2% 12.87bc 12.53cd 12.37cde 12.13cdef 12.17cdef 11.83defg 12.32B CaCl 3% 12.87bc 13.40ab 13.63a 13.83a 14.00a 13.40ab 13.52A

Mean** 12.87A 12.49B 12.46B 12.32B 12.20BC 11.93C

Surkh (Year 2)

LSD T= 0.23 W= 0.33 TW= 0.66

Table 19.2: Effect of calcium chloride on total soluble solids of “Sufaid” loquat


Water dip 12.8cde 12.8cde 12.87cde 11.73f 11.73f 10.6g 12.10B CaCl 1% 12.8cde 13.23bc 13.43abc 13.23bc 12.47de 12.50de 12.95A CaCl 2% 12.8cde 13.93a 13.53ab 13.23bc 12.33e 13.37abc 13.21A CaCl 3% 12.8cde 13.03bcd 13.07bcd 13.20bc 13.07bcd 12.50de 12.95A

Mean** 12.83B 13.26A 13.23A 12.85B 12.40C 12.24C

Surkh (Year 2)

LSD T= 0.46 W= 0.27 TW= 0.55


Water dip 12.97bcd 13.03bcd 12.93bcd 11.83ef 11.53f 10.63g 12.16C CaCl 1% 12.97bcd 12.77bcd 12.97bcd 12.60cd 12.63bcd 12.40de 12.72B CaCl 2% 12.97bcd 13.93a 13.23abc 13.17bcd 13.00bcd 13.20bc 13.25A CaCl 3% 12.97bcd 13.40ab 13.07bcd 13.20bc 13.27abc 12.87bcd 13.13A

Mean** 12.97AB 13.28A 13.05A 12.70BC 12.61C 12.27D

Surkh (Year 2)

LSD T= 0.29 W= 0.32 TW= 0.65


113

“Surkh” cv. of loquat. 1% CaCl2 had lower TSS (12.1 ○Brix ) during both years

compared to the higher concentrations. TSS increased gradually uptil 6th week in Surkh

variety (Table 21.1) and then started to decrease during storage with a final increase

towards the end of tenth week. Lowest TSS was recorded in control during both years

(Fig. 17). In Sufaid variety no significant difference was observed between different

treatments during the first year (Table 19.2), however during the second year 2% and 3%

CaCl2 treatments differed significantly from 1% CaCl2 and control by having higher

TSS (13.2 and 13.1 ○Brix ). TSS increased form 4th to 6th week and then started to

decrease gradually uptil 10th week of storage. Maximum decrease in TSS was observed in

control in both varieties while . 2% CaCl2 had higher TSS than day one.

Results of the above study indicate that CaCl2 treatments had a significant effect

on TSS with 2% and 3% CaCl2 showing good results. Increased TSS in 3% CaCl2 may

be because higher concentration of CaCl2 (3%) developed a thin layer on the fruit

surface which retarded the deterioration process and also lowered the rate of evaporation

from the fruits surface. The increase in TSS in during 2nd week upto 6th week during

storage was probably due to hydrolysis of polysaccharides and increase in the

concentration of the juice content due to dehydration. An initial increase then loss of

TSS in loquat has also been reported by (Ding et al., 1998a; Lin et al., 1999; Zheng et al.,

2000b). These results are supported by the findings of Wills et al. (1982) who reported

an elevation in TSS of apple fruits during storage period.

Deleted: Appendix

Deleted: Appendix

114



Three percent CaCl2 had the highest total sugars in “Surkh: cv. of loquat during

both years (Table 20.1) with only (6.2% and 6.8%) losses occurring in both years

compared to 8.2% and 14.5% in control. 1% and 2% CaCl2 had higher losses (10.6% and

15.2%). Control had higher total sugars compared with other treatments uptil second

week during both years of study. In “Sufaid” cv., 1% and 3% CaCl2 were statistically

superior to other treatments during both years (Table 20.2). 1% CaCl2 had the lowest

loss (5.5% and 6.1%) during both years followed by 7.9% and 8.5% in 3% CaCl2. Total

sugars decreased gradually during the ten week storage in all treatments (Fig. 18).


Lowest losses in reducing sugars of “Surkh” cv. (9.4% and 9.3%) were

recorded in 3% CaCl2 (Table 21.1) during both years which differed significantly from

rest of the treatments. Other concentration of CaCl2 were not very effective. Maximum

loss of 17.1% was recorded in 1% CaCl2 as compared to 13.1% in control during the first

year while during the second year, control had the highest loss (14.9%). Highest loss of

29.8% during the tenth week was recorded in 1% CaCl2 in the first year while control had

the highest loss (26.1%) in the tenth week during the second year. A gradual decrease in

reducing sugars was observed in all treatments during the storage period in both years.

In “Sufaid” cv., no significant difference was observed within the treatments

during the first year while during the second year 3% CaCl2 differed significantly from

Deleted: Appendix

Deleted: Appendix

Deleted: Appendix

115

A

4

6

8

10

0 2 4 6 8 10

Tota

l Sug

ars

(%)

C

4

6

8

10

0 2 4 6 8 10

B

4

6

8

10


Tota

l Sug

ars

(%)

D

4

6

8

10

0 2 4 6 8 10Storage periods (w eeks)

Water Dip AA 250 mg/l AA 500 mg/lAA 750 mg/l CA 250 mg/l CA 500 mg/lCA 750 mg/l

Fig. 18: Effect of calcium chloride agents on totals sugars in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.32, B = 0.30, C = 0.30, D = 0.43

116

Table 20.1: Effect of calcium chloride on totals sugars of “Surkh” loquat


Water dip 8.51a 8.58a 8.25ab 7.95def 7.22ghi 6.73jk 7.81AB CaCl 1% 8.51a 8.00bc 7.83cde 7.54efg 7.07hij 6.74jk 7.61AB CaCl 2% 8.51a 7.92bcd 7.40fgh 6.95ij 6.40kl 6.16l 7.22B CaCl 3% 8.51a 8.39a 8.26ab 7.99bc 7.46fg 7.30f-i 7.98A

Mean** 8.51A 8.22B 7.94C 7.52D 7.03E 6.73F

Surkh (Year 1)

LSD T= 0.64 W= 0.16 TW= 0.32


(T) 0 2 4 6 8 10 Means* Water dip 8.67a 8.42ab 8.19bcd 7.27f 6.34g 5.60h 7.41B CaCl 1% 8.67a 8.08b-e 7.91de 7.83e 7.40f 6.64g 7.75AB CaCl 2% 8.67a 8.03cde 7.87de 7.18f 6.60g 6.41g 7.46B CaCl 3% 8.67a 8.33abc 8.18b-e 8.10b-e 7.89de 7.34f 8.08A

Mean** 8.67A 8.21B 8.04C 7.59D 7.05E 6.50F

Surkh (Year 2)

LSD T= 0.54 W= 0.15 TW= 0.30

Table 20.2: Effect of calcium chloride on totals sugars of “Sufaid” loquat


Water dip 8.36a 8.25ab 7.99b-e 7.65ef 7.14h 6.06i 7.57AB CaCl 1% 8.36a 8.22ab 8.16abc 7.76def 7.64f 7.25gh 7.90A CaCl 2% 8.36a 8.06a-d 7.77def 6.39i 6.14i 5.55j 7.04B CaCl 3% 8.36a 8.19abc 7.87c-f 7.55fg 7.28gh 6.95h 7.70A

Mean** 8.36A 8.22B 7.94C 7.52D 7.03E 6.73F

Sufaid (Year 1)

LSD T= 0.53 W= 0.16 TW= 0.30


Water dip 8.58a 7.56efg 7.46fg 6.58h 6.20hi 5.66j 7.00B CaCl 1% 8.58a 8.45ab 8.19abc 8.02b-e 7.70def 7.43fg 8.06A CaCl 2% 8.58a 8.11a-d 7.94cde 7.32fg 6.16hi 5.80ij 7.32B CaCl 3% 8.58a 8.24abc 8.10a-d 7.67def 7.41fg 7.13g 7.85A

Mean** 8.58A 8.09B 7.92B 7.39C 6.87D 6.50E

Sufaid (Year 2)

LSD T= 0.39 W= 0.21 TW= 0.43


117

Table 21.1: Effect of calcium chloride on reducing sugars of “Surkh” loquat


Water dip 2.98a 2.77ab 2.66bc 2.49c-f 2.40d-g 2.24g 2.59AB CaCl 1% 2.98a 2.87a 2.25g 2.33fg 2.25g 2.18g 2.47B CaCl 2% 2.98a 2.91a 2.38efg 2.35efg 2.41d-g 2.29fg 2.55B CaCl 3% 2.98a 2.90a 2.65bc 2.62bcd 2.58b-e 2.51c-f 2.70A

Mean** 2.98A 2.86B 2.48C 2.45C 2.41C 2.30D

Surkh (Year 1)

LSD T= 0.14 W= 0.10 TW= 0.20


Water dip 3.02a 2.78b-e 2.67ef 2.47ghi 2.37ghi 2.14j 2.57B CaCl 1% 3.02a 2.90abc 2.48ghi 2.42ghi 2.32ij 2.32ij 2.58B CaCl 2% 3.02a 2.88a-d 2.48ghi 2.48ghi 2.42ghi 2.37hi 2.61B CaCl 3% 3.02a 2.92ab 2.70def 2.72c-f 2.57fg 2.54fgh 2.74A

Mean** 3.02A 2.87B 2.58C 2.52C 2.42D 2.34D

Surkh (Year 2)

LSD T= 0.09 W= 0.08 TW= 0.17

Table 21.2: Effect of calcium chloride on reducing sugars of “Sufaid” loquat


Water dip 2.85ab 2.73abc 2.57a-e 2.42c-f 2.44c-f 2.28ef 2.55 ns CaCl 1% 2.85ab 2.86ab 2.39def 2.36def 2.24f 2.28ef 2.50 ns CaCl 2% 2.85ab 2.87a 2.48c-f 2.40def 2.36def 2.38def 2.56 ns CaCl 3% 2.85ab 2.80ab 2.66a-d 2.57a-e 2.55b-f 2.57a-e 2.66 ns

Mean** 2.85A 2.81A 2.52B 2.44BC 2.39BC 2.37C

Sufaid (Year 1)

LSD T= 0.20 W= 0.13 TW= 0.26


(T) 0 2 4 6 8 10 Means* Water dip 2.97a 2.78bcd 2.61d-g 2.46ghi 2.36ij 2.16k 2.56B CaCl 1% 2.97a 2.84abc 2.53f-i 2.43g-j 2.40g-j 2.26jk 2.57B CaCl 2% 2.97a 2.89ab 2.57e-h 2.47ghi 2.42hij 2.46ghi 2.63B CaCl 3% 2.97a 2.94ab 2.72cde 2.69c-f 2.58e-h 2.56e-h 2.74A

Mean** 2.97A 2.86B 2.61C 2.51D 2.44DE 2.36E Sufaid (Y

ear 2) LSD T= 0.39 W= 0.07 TW= 0.15

*, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT) ns = Non significant

118

Table 22.1: Effect of calcium chloride on non-reducing sugars of “Surkh” loquat


Water dip 5.83ab 5.88a 5.63abc 4.98de 4.30fg 3.99g 5.10 ns CaCl 1% 5.83ab 5.31a-d 5.74ab 5.49a-d 5.12cde 4.71ef 5.37 ns CaCl 2% 5.83ab 5.06cde 5.28bcd 4.67ef 4.11g 4.10g 4.81 ns CaCl 3% 5.83ab 5.58ab 5.72ab 5.56abc 5.29bcd 4.97de 5.49 ns

Mean** 5.83A 5.46B 5.59AB 5.17C 4.70D 4.44E

Surkh (Year 1)

LSD T= 0.55 W= 0.24 TW= 0.48


Water dip 5.80a 5.78a 5.65ab 4.92de 4.08f 3.56g 4.96 ns CaCl 1% 5.80a 5.32bc 5.55abc 5.52abc 5.19cde 4.43f 5.30 ns CaCl 2% 5.80a 5.29bcd 5.51abc 4.82e 5.19cde 4.43f 4.98 ns CaCl 3% 5.80a 5.29bcd 5.51abc 4.82e 4.30f 4.15f 5.47 ns

Mean** 5.80A 5.48B 5.58B 5.19C 4.75D 4.27E

Surkh (Year 2)

LSD T= 0.50 W= 0.17 TW= 0.35 ns = Non significant Table 22.2: Effect of calcium chloride on non-reducing sugars of “Sufaid” loquat


Water dip 5.77a 5.31abc 5.30abc 4.52def 4.19efg 3.88fg 4.83B CaCl 1% 5.77a 5.68ab 5.90a 5.67ab 5.47abc 5.34abc 5.64A CaCl 2% 5.77a 5.37abc 5.51abc 4.72cde 3.93fg 3.68g 4.83B CaCl 3% 5.77a 5.56ab 5.47abc 5.18a-d 4.93b-e 4.75cde 5.28AB

Mean** 5.77A 5.48A 5.54A 5.02B 4.63C 4.41C

Sufaid (Year 1)

LSD T= 0.55 W= 0.33 TW= 0.67


(T) 0 2 4 6 8 10 Means* Water dip 5.76a 4.92de 4.97de 4.24f 3.95fg 3.60gh 4.57B CaCl 1% 5.76a 5.74a 5.78a 5.71ab 5.42abc 5.28bcd 5.61A CaCl 2% 5.76a 5.36a-d 5.50abc 4.97de 3.86fgh 3.46h 4.82B CaCl 3% 5.76a 5.45abc 5.52abc 5.10cde 4.96de 4.69e 5.24A

Mean** 5.76A 5.37B 5.44B 5.00C 4.55D 4.26E Sufaid (Y

ear 2) LSD T= 0.39 W= 0.20 TW= 0.40


119

rest of the treatments. Lowest losses during both years (6.7% and 7.7%) were recorded in

3% CaCl2 compared to 10.5% and 13.8% in control. Highest loss of 20% during the tenth

week was recorded in 1% CaCl2 in the first year while control had the highest loss

(27.3%) in the tenth week during the second year. Overall decrease in reducing sugars

was similar to decrease in Surkh cv.


No significant effect of CaCl2 treatments on non reducing sugars was observed during

both years on “Surkh” cultivar (Table 22.1). During the tenth week, highest loss in non

reducing sugars (31.6%) was recorded in control. During the second year,lowest loss

(5.7%) was recorded in 3% CaCl2 followed by 8.6% in 1% CaCl2. Greatest decrease

(38.6%) was recorded in control during the tenth week.

In “Sufaid” cv., during both years, 1% and 3% CaCl2 were statistically superior,

however during the second year, 3% CaCl2 was also at par with control and 2% CaCl2. In

terms of losses, 1% CaCl2 had the lowest losses (2.3% and 2.9%) in both years followed

by 8.5% and 9% in 3% CaCl2. In control the loss was 16.3% and 20.7% during both

years. Highest loss was recorded during the tenth week (36.2% and 39.9) in 2% CaCl2.

During both years, non reducing sugars decreased during the entire storage period with a

temporary increase during the fourth week after which a continual decrease was

observed.

Sugars and organic acids contents are key factors in determining taste attributes of

fruits. Sucrose is usually the carbon source in the glycolytic pathway and is composed of

a glucose and fructose molecule. Sucrose is a non reducing sugar and therefore a less

Deleted: Appendix

120

reactive molecule than the reducing sugars fructose and glucose. Often, sucrose is

imported into cells, sequestered in the vacuole and used during respiration; however,

other sugars are also translocated. (Mir and Beaudry, 2002). The degradation of sucrose

or other respiratory substrates has important implications in terms of quality maintenance

of harvested products. Sucrose is a sweet molecule and its flavor contributes significantly

to the perception of sweetness in many tissues. Nevertheless, its sweetness is only

roughly half the combined sweetness of its constituents, glucose and fructose. A molar

sucrose solution has a sweetness rating 1.0, whereas glucose has a rating of 0.6 and

fructose, 1.6. Breakdown of sucrose to individual sugars can, therefore, potentially

enhance sweetness. Most plants have large carbohydrate reserves, so sucrose depletion

may not impose a serious physiological limitation and a shift in sweetness of the tissue

may not be detectable. For tissues that contain little reserves, however, sucrose loss may

have serious negative implications, altering the expression of genes that may be related to

quality (King et al., 1995; Mir and Beaudry, 2002).

In the above study, total sugars, reducing and non reducing sugars decreased with

the progress of time during storage. However 3% CaCl2 significant decreased the losses

in all three sugars during the ten week storage. It was observed that 3% CaCl2 was

effective in maintaining total sugars of both Surkh and Sufaid cultivars during storage

and had lower losses as compared to other treatments. Concentration of reducing sugars

decreased during storage. Minimum losses 9.4% and 9.3% were recorded in Surkh, while

6.7% and 7.7% losses were recorded in Sufaid treated with 3% CaCl2 as compared to rest

of the treatments. Losses in non reducing sugars were significantly reduced by 1% and

3% CaCl2 treatments. Chardonnet et al. (2003) reported that the sucrose content in the

121

fruit tissue of untreated apple declined by 30% after 6 months storage, while fruit treated

with 3 or 4% CaCl2 had maximum sucrose content. Fructose and glucose content

increased during storage of apple. However, this immediate increase was temporary and a

20% decrease occured for both sugars from 2 weeks to 6 months storage in 0% CaCl2

treated fruit. Glucose content decreased with storage time, however, fruit stored for 2

weeks treated with 4% CaCl2 had 30% more glucose than fruit treated with 0% CaCl2.

Decrease in sugars during storage of loquat has also been reported Ding et al., 1997;

Ding et al., 1998b; Cai et al., 2006d; Amaros et al., 2008). The decrease in sugars during

storage may be attributed to their consumption as respiratory substrates (Mir and

Beaudry, 2002) which might explain the decrease in sugars of this study.

3.6.5 Effect on Titratable Acidity

Table 23.1 reveals no significant effect of calcium chloride treatments on cv.

“Surkh” of loquat during both years as all treatments were statistically similar. Highest

loss in TA was recorded in control, 1% and 2% CaCl2 during the last week of the

storage period. In “Sufaid” cultivar 2% CaCl2 retained significantly higher TA (0.48%

and 0.42%) during both years followed by 1% CaCl2. Control and 3% CaCl2 treatment

had no significant difference during the first year but differed significantly during the

second year. Lowest TA (0.29%) during the second year was recorded in control. TA

decreased continuously during storage in both years of study (Fig. 19).

Fruit flavor is a combination of taste (such as sweet or sour) and aroma. Total

soluble solids, titratable acidity and aroma volatile composition are all associated with

flavor and are commonly measured as part of fruit quality assessment (Ferguson and

Deleted: Appendix

122

A

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8 10

Titra

tabl

e Ac

idity

(%)

C

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8 10

B

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8 10


Titra

tabl

e Ac

idity

(%)

D

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8 10


Water Dip

CaCl 1%

CaCl 2%

CaCl 3%

Fig. 19: Effect of calcium chloride on titratable acidity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.05, B = 0.05, C = 0.02, D = 0.05

123

Table 23.1: Effect of calcium chloride on titratable acidity of “Surkh” loquat


Water dip 0.61 a 0.61 a 0.38 cd 0.33 ef 0.29 efg 0.19 hi 0.40 ns CaCl 1% 0.61 a 0.59 a 0.47 b 0.38 cd 0.28 fg 0.15 i 0.41 ns CaCl 2% 0.61 a 0.62 a 0.35 de 0.30 efg 0.20 hi 0.21 h 0.38 ns CaCl 3% 0.61 a 0.49 b 0.39 cd 0.29 fg 0.42 c 0.26 g 0.41 ns

Mean** 0.61A 0.58B 0.40C 0.32D 0.30D 0.20E

Surkh (Year 1)

LSD T= 0.03 W= 0.02 TW= 0.05


Water dip 0.59 a 0.47 c 0.36 de 0.25 gh 0.23 hi 0.14 j 0.41 ns CaCl 1% 0.59 a 0.53 b 0.46 c 0.35 def 0.25 gh 0.16 j 0.39 ns CaCl 2% 0.59 a 0.49 bc 0.40 d 0.29 g 0.25 gh 0.19 ij 0.37 ns CaCl 3% 0.59 a 0.50 bc 0.39 d 0.30 efg 0.30 fg 0.26 gh 0.39 ns

Mean** 0.59A 0.51B 0.42C 0.33D 0.27E 0.21F

Surkh (Year 2)

LSD T=0.10 W= 0.03 TW= 0.05 Table 23.2: Effect of calcium chloride on titratable acidity of “Sufaid” loquat


Water dip 0.54 d 0,28 hi 0.32 fgh 0.19 jk 0.18 jk 0.14 k 0.27C CaCl 1% 0.54 cd 0.68 b 0.44 e 0.37 f 0.19 jk 0.20 j 0.40B CaCl 2% 0.54 cd 0.75 a 0.58 c 0.49 de 0.34 fg 0.17 jk 0.48A CaCl 3% 0.54 cd 0.30 ghi 0.34 fgh 0.20 j 0.26 i 0.19 jk 0.30C

Mean** 0.54A 0.50B 0.42C 0.31D 0.24E 0.17F

Sufaid (Year 1)

LSD T= 0.04 W= 0.05 TW= 0.02


(T) 0 2 4 6 8 10 Means* Water dip 0.54 a 0.38 ef 0.29 g 0.23 hi 0.19 i 0.13 j 0.29D CaCl 1% 0.54 a 0.53 ab 0.45 cd 0.36 f 0.22 hi 0.18 i 0.38B CaCl 2% 0.54 a 0.50 abc 0.47 cd 0.42 de 0.37 ef 0.20 i 0.42A CaCl 3% 0.54 a 0.48 bc 0.35 f 0.20 hi 0.26 gh 0.19 i 0.34C

Mean** 0.54A 0.47B 0.39C 0.30D 0.26E 0.17F

Sufaid (Year 2)

LSD T= 0.02 W= 0.02 TW= 0.05


124

boyd, 2002). In loquat, Malic acid is the main organic acid which accounts for about

90% of the total organic acids present (Ding et al., 1998a). Appendices 23.1 and 23.2,

indicated that TA% of loquat fruits decreased gradually as storage period advanced for

both, treated and control fruits. TA was not influenced by the postharvest calcium dips in

Surkh loquat, however Sufaid loquat showed some response towards the treatments. 2%

CaCl2 had higher TSS at the end of ten week storage followed by 1% CaCl2. These

results support the findings of Manganaris et al. (2005) who reported that postharvest

calcium chloride dips did not effect TA % in peaches during a four weeks of storage. De

Souza et. al. (1999) also reported that strawberry fruit dipped in 0, 0.5 and 1% calcium

chloride solution (CaCl2) had no significant effect on the physic-chemical characteristics

such as: pH, total soluble solids, total titratable acidity, during cold storage at 4 °C in an

modified atmosphere.

3.6.6 Effect on SOD Activity

Treatment means of “Surkh” cv. (Table 24.1) reveal that control and 2% CaCl2had higher

SOD content (39.41 and 39.56 U/g FW) and were statistically similar, followed by 3%

CaCl2 during the first year, while 1% CaCl2 had the lowest activity (30.91 U/g FW).

Overall enzyme activity was highest (42.6 U/g FW) during the first week and decreased

thereafter. There was a sudden decrease in activity during the sixth week followed by an

increase and again decrease during the last week (Fig. 20). Maximum activity (56.17 U/g

FW) was recorded in control during the fourth week. During the second year, again

control showed higher activity (41.97 U/g FW) followed by 2% (40.41

Deleted: Appendix

125

A

0

10

20

30

40

50

60

0 2 4 6 8 10

U/g

FW

C

0

10

20

30

40

50

60

0 2 4 6 8 10

B

0

10

20

30

40

50

60

0 2 4 6 8 10


U/g

FW

D

0

10

20

30

40

50

60

0 2 4 6 8 10



Fig. 20: Effect of calcium chloride agents on SOD activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 3.99, B = 4.96, C = 4.96, D = 4.01

126

Table 24.1: Effect of calcium chloride on SOD of “Surkh” loquat


Water dip 42.60cd 38.07e 56.17a 40.00de 27.50gh 32.10f 39.41A CaCl 1% 42.60cd 29.80fg 33.30f 32.80f 23.93hi 23.03i 30.91C CaCl 2% 42.60cd 50.17b 28.80fg 23.87hi 45.63c 46.27bc 39.56A CaCl 3% 42.60cd 44.20cd 29.33fg 25.60cd 43.97cd 28.97fg 35.78B

Mean** 42.60A 40.56B 36.90C 30.57E 35.26C 32.59D

Surkh (Year 1)

LSD T= 1.83 W= 1.99 TW= 3.99


Water dip 47.93b 42.10d 45.93bc 53.73a 35.80efg 26.33k 41.97A CaCl 1% 47.93b 34.40fgh 37.67ef 30.03ij 31.57hi 29.67ijk 35.21D CaCl 2% 47.93b 44.77bcd 47.30b 35.13fg 38.87e 28.43ijk 40.41B CaCl 3% 47.93b 53.63a 42.83cd 34.20gh 28.03jk 27.70jk 39.06C

Mean** 47.93A 43.72B 43.43B 38.28C 33.57D 28.03E

Surkh (Year 2)

LSD T= 0.93 W= 1.39 TW= 4.96

Table 24.2: Effect of calcium chloride on SOD of “Sufaid” loquat


Water dip 45.53a 46.20a 26.87efg 23.20gh 27.70efg 21.00h 31.75C CaCl 1% 45.53a 36.33bc 31.67cde 26.93efg 26.67efg 36.03bc 33.86B CaCl 2% 45.53a 38.77b 24.87fgh 30.73cde 31.37cde 28.50efg 33.30B CaCl 3% 45.53a 39.27b 29.10def 32.03cde 34.57bcd 32.27cde 35.46AB

Mean** 45.53A 40.14B 28.13D 28.23D 30.07D 29.45D

Sufaid (Year 1)

LSD T= 2.01 W= 2.48 TW= 4.96


Water dip 49.37a 45.33ab 24.20g 26.87fg 26.33fg 27.90fg 41.97A CaCl 1% 49.37a 44.67b 47.27ab 32.63de 27.67fg 27.90fg 35.21D CaCl 2% 49.37a 29.10ef 32.33de 36.77cd 34.37cd 27.73fg 40.41B CaCl 3% 49.37a 48.53ab 36.40cd 33.63cd 37.53c 26.93fg 39.06C

Mean** 49.37A 41.91B 35.05C 32.47D 31.48D 27.62E Sufaid (Y

ear 2) LSD T= 0.93 W= 2.00 TW= 4.01


127

U/g FW ) while 3% and 1% CaCl2 had lower activity respectively. Overall activity

decreased during the ten week storage.

In Sufaid variety high activity (36.46 and 35.46 U/g FW) was observed in 2%

and 3% CaCl2 as compared to control which had the least activity (31.75 U/g FW) during

the first year (Table 24.2). 1% CaCl2 treatment was statistically with 3% CaCl2. SOD

activity decreased until the sixth week with a temporary increase during the eight week

and again declined in the tenth week. During the second year, control had maximum

activity (41.97 U/g FW) followed by 2% CaCl2 (40.41 U/g FW) while 1% CaCl2 had the

lowest activity (35.21 U/g FW). Overall a decreasing trend was observed during the

entire storage period. Highest activity (47.27 U/g FW) was recorded in 1% CaCl2 during

the fourth week.

Calcium is known to have a role in membrane stability (Kirkby and Pilbeam,

1984). Calcium contributed to the linkages between pectic substances within the cell wall

and is believed that Ca2+ ions increases the cohesion of cell-walls (Demarty et al., 1984).

Although calcium dips have been known to delay membrane deterioration, the level of

benefits has not been promising as compared to other treatments in controlling membrane

injuries which lead to tissue deterioration (Whitaker et al., 1997; Hodges, 2003). Calcium

applied exogenously stabilized plant cell walls and shield it from cell wall degrading

enzymes (White and Broadley, 2003).

Our study shows that calcium treatments did not have a significant effect on SOD

activity of Surkh variety. SOD does not always respond to physiological states of fruits,

however the differences in SOD activity among cultivars may predispose them to storage

Deleted: Appendix

128

disorders (Hodges, 2003). SOD and H2O2 can disrupt Ca2+ -ATPase activity causing a

prolonged release of calcium and elevation of cytoplasmic calcium content (Paliyath and

Droillard, 1992) which promotes decompartmentation and increase in cytoplasmic

hydrogen ion concentration leading to stimulated phospholipase-D activity and formation

of phosphatidic acid. Both O2 and H2O2 if not catabolised, will be transformed to active

oxygen species (AOS) and induce lipid peroxidation and accelerate the deteriorative

cycle associated with oxidative stress and fruit senescence (Bowler et al., 1992). SOD

transforms the harmful superoxide radical and hydrogen peroxide to molecular oxygen

and water in combination with catalase, thus averting cellular damage (Scandalios,

1993a). In this study there was a poor correlation of between SOD and CAT. Spychalla

and Desborough (1990) and Kawakami et al. (2000) have also reported similar findings.

This might be due to the fact that compared with control fruit, the degree of oxidative

stress varied in treatments which caused higher SOD activity.


Log values of Catalase (CAT) activity in “Surkh” cv. during the ten week

storage show that 1% and 2% CaCl2 had relatively higher activity (2.95 and 3.00 U/g

FW) as compared to control (2.65 U/g FW) and 3% CaCl2 (2.77 U/g FW). CAT activity

increased during the first two weeks (2.99 U/g FW) as compared to day one (2.47 U/g

FW) and started to decrease thereafter with a surge during the eight week (Table 25.1). A

fluctuating trend was observed during the tenth week in different treatments. During the

second year 2% CaCl2 and 3% CaCl2 had higher activity (2.92 and 2.83 U/g FW) as

compared to control and 1% CaCl2 (2.77 and 2.81 U/g FW). CAT activity started

Deleted: 89

Deleted: Appendix

129

A

0

1000

2000

3000

0 2 4 6 8 10

U/g

FW

C

0

1000

2000

3000

0 2 4 6 8 10

B

0

1000

2000

3000


U/g

FW

D

0

1000

2000

3000

0 2 4 6 8 10


Water Dip

CaCl 1%

CaCl 2%

CaCl 3%

Fig 21: Effect of calcium chloride on catalase activity in loquat cv. “Surkh” during 1st

year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.04, B = 0.66, C = 0.07, D = 0.06

Deleted: yer

130

Table 25.1: Effect of calcium chloride on catalase activity of “Surkh” loquat


Means*

Water dip 2.47j 3.04cde 2.91fg 2.33k 2.61i 2.58i 2.65C CaCl 1% 2.47j 2.95ef 2.84gh 3.12abc 3.20a 3.12abc 2.95AB CaCl 2% 2.47j 3.00def 3.17ab 3.0cd 3.20a 3.09bcd 3.00A CaCl 3% 2.47j 2.95ef 2.81h 3.08bcd 2.85gh 2.48j 2.77BC

Mean** 2.47E 2.99A 2.93BC 2.90C 2.96AB 2.82D

Surkh (Year 1)

LSD T=0.05 W=0.09 TW= 0.04


Means*

Water dip 2.80efg 3.15a 2.90cde 2.59gh 2.69gh 2.51i 2.77B CaCl 1% 2.80efg 3.13aa 2.87edf 2.73fgh 2.81efg 2.54i 2.81B CaCl 2% 2.80efg 3.10ab 3.08ab 2.97bcd 2.80efg 2.76efg 2.92A CaCl 3% 2.80efg 3.07abc 3.04abc 2.70gh 2.82d-g 2.58hi 2.83AB

Mean** 2.80C 3.10A 2.97B 2.75C 2.78C 2.60D

Surkh (Year 2)

LSD T=0.09 W=0.14 TW= 0.06

Table 25.2: Effect of calcium chloride on catalase activity of “Sufaid” loquat


Means

Water dip 2.78hi 3.08e 2.77hi 2.25jk 2.19k 2.22jk 2.55C CaCl 1% 2.78hi 3.35a 2.89g 3.26b 2.18cd 2.97f 3.07A CaCl 2% 2.78hi 2.98f 3.14de 3.16de 3.24bc 2.74i 3.01A CaCl 3% 2.78hi 2.78hi 2.71i 3.13de 2.85gh 2.29j 2.75B

Mean* 2.78D 3.05A 2.88C 2.95B 2.86C 2.55E

Sufaid (Year 1)

LSD T=0.15 W=0.03 TW= 0.07


Means*

Water dip 2.85d-g 3.14ab 2.78e-h 2.56ij 2.20k 2.12k 2.61B CaCl 1% 2.85d-g 3.17a 2.94cde 2.90c-f 2.71ghi 2.53j 2.85A CaCl 2% 2.85d-g 2.85d-g 3.02abc 3.04abc 2.70ghi 2.28d-g 2.83A CaCl 3% 2.85d-g 2.99bcd 2.75fgh 3.05abc 2.84d-h 2.69hi 2.86A

Mean** 2.85BC 3.08A 2.88B 2.80C 2.64D 2.48E Sufaid(Y

ear 2) LSD T=0.09 W=0.13 TW= 0.06


131

to decrease after two weeks of storage, however the activity remained higher in 2% and

3% CaCl2 until the fourth week (Fig. 21). In “Sufaid” cv. of loquat (Table 25.2), 2%

CaCl2 and 3% CaCl2 retained maximum activity (3.07 and 3.01 U/g FW) while control

had the lowest activity (2.55 U/g FW). Maximum CAT activity (3.05 U/g FW) was

recorded during the second week as compared to day one (2.78 U/g FW) and then started

to decrease till the end of ten week storage period. High activity (3.26 and 3.13 U/g FW)

was recorded in 1% and 3% CaCl2 during the sixth week while 2% CaCl2 showed greater

activity (3.24 U/g FW) during the eight week. During the second year, no significant

difference was observed among different concentrations of CaCl2, however they differed

significantly from control. A general decreasing trend in activity was observed after an

initial increase during the second week with a maximum value of 3.08 U/g FW and

ending at 2.48 U/g FW at the end of tenth week.

Fruit ripening and leaf senescence studies have shown that senescence depends on

the status of tissue calcium. By increasing levels of calcium, different parameters such as

senescence, respiration, chlorophyll content and fluidity of membranes are changed

(Poovaiah, 1988). Catalase activity is known to decrease during low temperature storage

(Wang, 1995). Our results also show that application of different calcium concentrations

maintained CAT higher activity during the entire storage period as compared to control.

This possible reason may be that calcium maintained respiration activities in treated

fruits.

Deleted: Appendix

132

3.6.8 Effect on POD Activity

Changes in POD activity (Table 26.1) of “Surkh” cv of loquat reveal that control

and 1% CaCl2 had high activity during the first year. Control was statistically similar

with 2% and 3% CaCl2. Lowest activity during the tenth week was recorded in control

(3.36 U/g FW) while highest (3.71 U/g FW) was recorded in 3% CaCl2. During the

second year, 1% and 3% CaCl2 had maximum activity (3.26 and 3.30 U/g FW) followed

by control (3.14 U/g FW). Lowest activity (3.04 U/g FW) was recorded in 2% CaCl2. At

the end of tenth week, there was high POD activity in control (3.97 U/g FW) followed

by 3% CaCl2 (3.71 U/g FW). Overall activity kept changing during the storage, reaching

its highest in the sixth week, declining till the eight week and again increaseing in the

tenth week.

In Sufaid variety, highest activity (3.29 U/g FW) was observed in 1% CaCl2 ,

followed by 3.08 and 3.06 U/g FW in control and 3% during the first year (Table 26.2).

Lowest activity (2.94 U/g FW) was recorded in 2% CaCl2. At the end of tenth week, 2%

CaCl2 had maximum activity (3.81 U/g FW), while control had the lowest activity (2.30

U/g FW). During the second year, control and 1% CaCl2 had maximum activity (3.20

and 3.24 U/g FW) followed by 2% and 3% CaCl2 (3.07 and 3.05 U/g FW). POD activity

increased gradually till the sixth week, declined in the eight week and again increased in

the tenth week (Fig 22).

Flesh browning is of great concern regarding fruits and is related to quality

deterioration of loquat. It is associated with phenol-related metabolic enzymes POD and

PPO (Loaiza and Saltveit, 2001). POD catalyzes the decomposition of H2O2, by

Deleted: Appendix

Deleted: Appendix

133

liberating free radicals instead of oxygen (Burris, 1960). The peroxidases in the cell walls

utilize H2O2 and generate phenoxy compounds which polymerize to produce components

such as lignin (Greppin et al., 1986). Francois and Espin (2001) reported that PPO and

POD are the main enzymes responsible for quality loss due to Phenolic degradation.

Bruising and physiological stress may enhance POD activity due to increased oxidative

stress in the fruits (Lamikanra and Watson, 2001).

Calcium is the important mineral constituent and it is the constituent of middle

lamellae. Softening of fruits is mainly due to weakening of middle lamellae during

ripening. Calcium helps to bind polygalactonic acid each other and make the membrane

strong and rigid (Dhruba and Gautam, 2006). Although calcium dips have been found to

delay membrane deterioration, the results have not been promising as compared to other

treatments in controlling tissue deterioration (Whitaker et al., 1997; Hodges, 2003).

Exogenously applied calcium stabilizes plant cell walls and protects them from cell wall

degrading enzymes (White and Broadley, 2003).

Our study show that POD activity fluctuated during the entire storage period and

was higher at the end of ten week storage as compared to day one. POD activity of loquat

has been found to change during storage (Ding et al., 2006). Increase in POD activity

during fruit maturation and senescence has been observed by Aydin and Kadioglu (2001).

El-hilali et al. (2003) also reported an increase in POD activity in mandarin during a 30

day storage period at 4 °C, with smallest changes in POD activity recorded in fruit

treated with 1% Ca(NO3)2.4H2O. Similar results on papaya stored at 5 °C and 15 °C for

upto 30 days have been reported by Setha et al. (2000) and zucchini squash during

134

A

1

2

3

4

5

0 2 4 6 8 10

U/g

FW

C

1

2

3

4

5

0 2 4 6 8 10 B

1

2

3

4

5

0 2 4 6 8 10


U/g

FW

D

1

2

3

4

5



Fig. 22: Effect of calcium chloride agents on POD activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.10, B = 0.10, C = 0.09, D = 0.14

135

Table 26.1: Effect of calcium chloride on POD activity of “Surkh” loquat


Water dip 2.26 k 3.30 gh 3.74 cd 4.19 a 2.33 k 3.36 fg 3.20AB CaCl 1% 2.26 k 2.91 j 3.68 d 3.05 i 3.92 b 3.66 d 3.25A CaCl 2% 2.26 k 3.06 i 3.28 gh 3.29 gh 3.82 bc 3.43 ef 3.19B CaCl 3% 2.26 k 3.19 h 3.52 e 3.07 i 3.23 h 3.71 d 3.17B

Mean** 2.26E 3.12D 3.56A 3.40B 3.32C 3.54A

Surkh (Year 1)

LSD T= 0.05 W= 0.05 TW= 0.10


Water dip 2.4 0l 2.65j 3.46e 3.45e 2.93i 3.97a 3.14B CaCl 1% 2.4 0l 2.51k 3.36ef 3.97a 3.60d 3.71c 3.26A CaCl 2% 2.4 0l 2.68j 3.28fg 3.29fg 3.20gh 3.43e 3.04C CaCl 3% 2.4 0l 3.01i 3.82b 4.04a 3.15h 3.38ef 3.30A

Mean** 2.4 0 F 2.71E 3.48C 3.69A 3.22D 3.62B

Surkh (Year 2)

LSD T= 0.06 W= 0.05 TW= 0.10 Table 26.2: Effect of calcium chloride on POD activity of “Sufaid” loquat


Water dip 2.30m 3.39f 3.29g 3.62d 2.59l 3.29g 3.08B CaCl 1% 2.30m 3.30fg 3.76ab 3.06ij 3.71bc 3.63cd 3.29A CaCl 2% 2.30m 3.01j 3.51e 2.81k 2.22m 3.81a 2.94C CaCl 3% 2.30m 3.31fg 3.58de 3.11hi 2.88k 3.16h 3.06B

Mean** 2.30F 3.25C 3.53A 3.15D 2.85E 3.47B

Sufaid (Year 1)

LSD T= 0.07 W= 0.04 TW= 0.09


Water dip 2.31k 2.93i 3.53de 3.24h 3.30gh 3.91a 3.20A CaCl 1% 2.31k 2.89i 3.72bc 3.81ab 3.35fgh 3.38e-h 3.24A CaCl 2% 2.31k 2.68j 3.46d-g 3.34gh 2.81ij 3.85ab 3.07B CaCl 3% 2.31k 2.81ij 3.39e-h 3.60cd 2.68j 3.51def 3.05B

Mean** 2.31E 2.82D 3.52B 3.50B 3.03C 3.66A Sufaid (Y

ear 2) LSD T= 0.01 W= 0.07 TW= 0.14


Formatted: Font: 10 pt

136

storage at 5°C (Wang, 1995). Ruoyi et al. (2005) state that the activity of POD in the

control treatment of peaches decreased during the first 25 days of storage due to the

inhibition of low temperature while POD in the fruits treated with 1% chitosan coating +

PEpackage, 1% chitosan + 0.5% CaCl2 coating + PE package, , and 1% chitosan + 0.5 %

CaCl2 coating + PE package + IW increased markedly within 25 days and lowered down

afterwards and related the changes to stress during the first 25 days of storage, and the

suppression effect later on. Therefore, all treatments had lower POD activities as

compared to control.

In this study 2% cc treatment had lower POD activity in Surkh loquat during both

years, while 2% and 3% cc had lower POD activity in Sufaid loquat. The lower activity

in these treatments may be due less oxidative stress as compared to the other treatments

and the increase in POD activity may be due to a need for H2O2 detoxification induced by

the senescence process as stated by Neill et al. (2002).

3.6.9 Effect on Ascorbic Acid Content

All three concentrations of calcium chloride (CaCl2) in “Surkh” cultivar were

similar in effect during the first year while 3% CaCl2 had significantly higher ascorbic

acid (AA) in the next year (Table 27.1). Maximum AA losses (48.1% and 46.9%)

occurred in control in the tenth week during both years. In the first year, 1% and 2%

CaCl2 had a loss of 10.9% and 8.4% compared to 19% loss in control whereas this loss

was 13.7% and 10% during the second year compared to 18.4% in control. Ascorbic acid

level decreased gradually during the ten week storage period during both years (Fig. 23).

Maximum AA level (3.26 mg/100ml) was recorded during the fourth week in 3% CaCl2.

Deleted: Appendix

137

A

1

2

3

4

0 2 4 6 8 10

Vit C

(m

g/10

0g F

W)

C

1

2

3

4

0 2 4 6 8 10

B

1

2

3

4


Vit C

(m

g/10

0g F

W)

D

1

2

3

4


Water Dip

CaCl 1%

CaCl 2%

CaCl 3%

Fig. 23: Effect of calcium chloride treatments on ascorbic acid content in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.32, B = 0.17, C = 0.30, D = 0.18

138

Table 27.1: Effect of calcium chloride on ascorbic acid content of “Surkh” loquat


Water dip 3.20abc 3.16abc 2.83c-f 2.43gh 2.26h 1.66i 2.59B CaCl 1% 3.20abc 3.13abc 2.96a-e 2.73d-g 2.60e-h 2.50fgh 2.85A CaCl 2% 3.20abc 3.06abc 2.93a-e 2.86b-f 2.83c-f 2.70d-g 2.93A CaCl 3% 3.20abc 3.13abc 3.26a 3.23ab 3.00a-d 2.90a-e 3.12A

Mean** 3.20A 3.12AB 3.00B 2.81C 2.65C 2.44D

Surkh (Year 1)

LSD T= 0.26 W= 0.16 TW= 0.32


(T) 0 2 4 6 8 10 Means* Water dip 3.26a 3.15ab 3.04b 2.56ef 2.20h 1.73i 2.66D CaCl 1% 3.26a 3.10ab 2.76cd 2.63de 2.43fg 2.36gh 2.76C CaCl 2% 3.26a 3.13ab 2.80cd 2.83c 2.73cde 2.56ef 2.88B CaCl 3% 3.26a 3.06ab 3.06ab 3.03b 2.83c 2.76cd 3.00A

Mean** 3.26A 3.11B 2.91C 2.76D 2.55E 2.35F

Surkh (Year 2)

LSD T= 0.08 W= 0.08 TW= 0.17

Table 27.2: Effect of calcium chloride on ascorbic acid content of “Sufaid” loquat


Water dip 3.16ab 3.00abc 2.83bcd 2.53de 2.26e 1.63f 2.57B CaCl 1% 3.16ab 3.20ab 3.00abc 2.86bcd 2.73cd 2.53de 2.91A CaCl 2% 3.16ab 3.14ab 3.10ab 3.03abc 2.90bc 2.90bc 3.00A CaCl 3% 3.16ab 3.16ab 3.26a 3.03abc 3.00abc 2.93abc 3.09A

Mean** 3.16A 3.13A 3.03A 2.83B 2.72B 2.43C

Sufaid (Year 1)

LSD T= 0.27 W= 0.15 TW= 0.30


(T) 0 2 4 6 8 10 Means* Water dip 3.23a 3.09bc 2.76cd 2.44fgh 2.20i 1.70j 2.54B CaCl 1% 3.23a 3.03ab 2.60efg 2.43gh 2.33hi 2.20i 2.63B CaCl 2% 3.23a 3.08ab 2.73def 2.60efg 2.43gh 2.43gh 2.75AB CaCl 3% 3.23a 3.10ab 3.00bc 2.80de 2.73def 2.70def 2.92A

Mean** 3.23A 3.07B 2.76C 2.58D 2.41E 2.23F

Sufaid (Year 2)

LSD T= 0.20 W= 0.09 TW= 0.18


139

The pattern of decrease was similar in “Sufaid” cv. as observed in Surkh . All

CaCl2 treatments had significantly higher AA content compared to control during the

first year, whereas during the second year, higher concentrations were statistically

superior. Storage period means reveal a decrease in AA content during the ten week

storage, however during the first year, no significant decrease was observed during the

first four weeks. Maximum losses were recorded in control in the tenth week during both

years.

Ascorbic acid is an important nutrient quality parameter of fruits and vegetables.

It is very sensitive to degradation as compared to other nutrients during processing of

foods and storage. It is believed that if ascorbic acid is retained during processing and

storage, other nutrients would be as well (Ozkan et al., 2004), however, during

processing and storage its levels tend to decrease (Veltman, 2000). According to Watada

et al. (1987), Vitamin C losses in fruits were associated with senescence and

deterioration in quality. Our results show that CaCl2 treatments had a significant effect as

compared to control on retaining ascorbic acid content in loquat fruit after ten week

storage period. These results verify the findings of Ruoyi et al. (2005) who stated that

AA content of peaches was maintained in a fifty day storage with application of 0.5%

postharvest treatment.

3.6.10 Effect on Radical Scavenging Activity

Radical Scavenging Activity (RSA) in terms of percent inhibition in “Surkh”

cultivar of loquat during storage show that higher concentrations of calcium chloride

(CaCl2) were significantly superior to control during both years (Table 28.1). RSA Deleted: Appendix

140

decreased until the sixth week in all treatments, after which it started to increase towards

the end of storage period. 2% and 3% CaCl2 had significantly higher RSA in the tenth

week during both years.

In “Sufaid” cultivar all CaCl2 concentrations had significantly higher RSA than

control during both years (Table 28.2), however they did not vary significantly among

each other. During both years RSA decreased during the first six weeks and then started

to increase towards the end of storage period. RSA in all concentrations was

significantly higher than control from the eighth week till the end of storage (Fig 24).

Plants are protected against conditions that generate high levels of reactive

oxygen species (ROS) by a complex antioxidant system. Harvested horticultural crops

undergo postharvest stresses which are superimposed on the natural ripening or

senescence process, producing ROS in the tissues. Internal quality and rate of senescence

of fruits and vegetables in storage have been linked to antioxidants (Lurie, 2003). When

a plant is stressed, the production of oxygen can exceed the scavenging capacity,

resulting in oxidative damage. Lipid peroxidation of plant membranes the intermediate

step of some crucial events during postharvest storage (Karakas and Yıldız, 2007).

Under prolonged oxidative conditions, active oxygen would cause lipid peroxidation,

DNA damage, and protein denaturation (Kawakami, 2000) and can also affect

anthocyanin, phenolic compound levels and antioxidant activity in fruits and vegetables

(Fernando et al., 2004).

Deleted: Appendix

141

A

0

20

40

60

80

100

0 2 4 6 8 10

% In

hibi

tion

C

0

20

40

60

80

100

0 2 4 6 8 10

B

0

20

40

60

80

100

0 2 4 6 8 10


% In

hibi

tion

D

0

20

40

60

80

100

0 2 4 6 8 10



Fig. 24: Effect of calcium chloride agents on radical scavenging activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSd for A = 5.16, B = 5.80, C = 6.90, D = 6.93

142

Table 28.1: Effect of calcium chloride on radical scavenging activity of “Surkh” loquat


Water dip 59.07ab 42.87f-i 40.10g-j 36.37jk 43.27f-i 46.40def 44.68C CaCl 1% 59.07ab 57.27ab 33.83k 37.63ijk 50.10cd 49.53cde 47.91BC CaCl 2% 59.07ab 45.67d-g 39.50hij 49.20cde 53.37bc 56.67b 50.58AB CaCl 3% 59.07ab 54.33bc 43.87e- h 45.97def 54.63bc 62.67a 53.42A

Mean** 59.07A 50.03C 39.33E 42.29D 50.34C 53.82B

Surkh (Year 1)

LSD T= 4.80 W= 2.58 TW= 5.16


Water dip 61.97b 39.70e-h 39.80e-h 37.43fgh 40.33efg 33.43h 42.11C CaCl 1% 61.97b 59.47b 37.07fgh 33.70gh 43.07ef 41.40ef 46.11BC CaCl 2% 61.97b 51.07c 41.13ef 39.93e-h 42.07ef 61.00b 49.53AB CaCl 3% 61.97b 50.10cd 42.77ef 44.60de 39.77e-h 74.03a 52.21A

Mean** 61.97A 50.08B 40.19C 38.92C 41.31C 52.47B

Surkh (Year 2)

LSD T= 3.99 W= 2.90 TW= 5.80

Table 28.2: Effect of calcium chloride on radical scavenging activity of “Sufaid” loquat


Water dip 60.77a 39.47fgh 33.07h 36.17gh 43.00d-g 42.73d-g 42.53B CaCl 1% 60.77a 58.47ab 39.57fgh 40.03e-g 48.57cd 58.60ab 51.00A CaCl 2% 60.77a 54.90abc 48.20cd 41.73d-g 52.57bc 59.77ab 52.99A CaCl 3% 60.77a 53.80abc 44.20def 47.30c-f 57.00ab 47.83cde 51.82A

Mean** 60.77A 53.38B 39.83D 45.30C 56.95A 53.82B

Sufaid (Year 1)

LSD T= 5.45 W= 0.04 TW= 6.90


Water dip 62.10ab 38.90hij 36.30ij 33.97j 34.23j 37.17hij 40.44C CaCl 1% 62.10ab 50.73def 42.60ghi 33.43j 49.40efg 54.00cde 48.71B CaCl 2% 62.10ab 67.13a 44.57fgh 48.67efg 49.63efg 57.50bcd 54.93A CaCl 3% 62.10ab 36.17ij 49.80efg 39.33hij 48.83efg 60.97abc 49.53B

Mean** 62.10A 48.23C 43.32D 38.85E 45.53CD 52.41B

Sufaid (Year 2)

LSD T= 4.88 W= 3.46 TW= 6.93


143

Calcium plays an important role in membrane stability (Kirkby and Pilbeam,

1984) by contributing to the linkages between pectic substances within the cell-wall.

Ca2+ ions increases the cohesion of cell-walls (Demarty et al., 1984). Although calcium

dips have been claimed to delay membrane deterioration even then its efficacy is less as

compared to other treatments in controlling membrane injuries leading to tissue

deterioration (Whitaker et al., 1997; Hodges, 2003). Calcium applied at pre- and

postharvest stages can detain senescence during storage of fruits with no adverse effect

on quality (Lester & Grusak, 2004).

In this study, calcium treatments showed a significant influence on the RSA. The

higher concentrations being more effective than the lower ones. A general decreasing

trend in RSA followed by an increase in RSA was also seen. Increase in RSA during

storage of fruits have been reported by Cocci et al. (2006) in apples and Del Caro et al.,

(2004) in mandarin, however there are antioxidant capacity of fruits and vegetables is

affected by several compounds (Vina & Chaves, 2003). Flavonoids, phenolic acids,

aminoacids, ascorbic acid (AA), tocopherols and pigments may promote antioxidant

(Chu et al., 2000). In this study AA showed a positive correlation (r = 0.99 and 0.99) in

Surkh and (r = 0.95 and 0.57) in Sufaid with RSA, proving that there a relationship of

between the two parameters existed. The initial decrease in RSA is in accordance with

the findings of Srilaong and Tatsumi (2003) who have reported a decrease in RSA

activity with the progress of senescence. Similarly the increase during the last weeks of

storage may be explained by fact that during advanced tissue senescence when

membranes are damaged the concentration of antioxidant substances including AA is

increased in order to repair or counterbalance the damage. This AA regeneration is used

144

to level off the increasing production of ROS and other free radicals (Sonia and Chaves,

2006).

3.6.11 Effect on PPO Activity

Maximum PPO activity in “Surkh” cv. of loquat (Table 29.1), was recorded in

control during both years. 1% and 2% CaCl2 had relatively lower activity (23.25 and

22.27 U/g FW) as compared to control in the first year. Maximum inhibition of PPO

activity (14.23 U/g FW) was recorded in 3% CaCl2. PPO activity was high during the

fourth and sixth week of storage. Maximum activity (77.46 U/g FW) was recorded in

control during the fourth week. During the second year, maximum activity (45.2 and

44.03 U/g FW) was recorded in control and 1% CaCl2. Maximum inhibition of PPO was

observed in 2% and 3% CaCl2 (27.11 and 25.41 U/g FW).

In “Sufaid” cv. of loquat (Table 29.2), maximum PPO activity (39.86 and 43.33

U/g FW) was recorded in control while 3% CaCl2 had maximum inhibition of PPO

(20.98 and 24.83 U/g FW) during both years. 1% CaCl2 and 2% CaCl2 had significantly

lower activity during the first year compared to control. Overall, high activity of PPO

(55.71 U/g FW) was observed during sixth week of storage. Highest PPO activity (73.7

u/g FW) in the first year, was recorded in 1% CaCl2 during the sixth week. Control had

higher activity (69.73 and 64.53 u/g FW) during the fourth and sixth week. During the

second year, 1% CaCl2 was statistically similar to control. 2% had greater inhibition on

PPO activity (34.32 U/g FW). PPO activity was higher during the eight week of storage

(Fig. 25). Maximum activity (79.84 U/g FW) was recorded during the

Deleted: et al.

Deleted: Appendix

Deleted: Appendix

145

A

0

20

40

60

80

100

0 2 4 6 8 10

U/g

FW

C

C

0

20

40

60

80

100

0 2 4 6 8 10

B

0

20

40

60

80

100


U/g

FW

D

0

20

40

60

80

100



Fig. 25: Effect of calcium chloride on PPO activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 6.09, B = 7.78, C = 7.86, D = 7.63

146

Table 29.1: Effect of calcium chloride on PPO activity of “Surkh” loquat


Water dip 0.61l 8.87jk 77.46a 68.21b 58.11c 32.58ef 40.98A CaCl 1% 0.61l 6.84jkl 32.52ef 35.29e 46.59d 17.64hi 23.25B CaCl 2% 0.61l 5.25kl 39.14e 37.91e 27.54fg 5.25kl 22.27B CaCl 3% 0.61l 4.83kl 21.74gh 28.08fg 12.92ij 17.17hi 14.23C

Mean** 0.61E 6.44D 42.72A 42.38A 36.29B 22.64C

Surkh (Year 1)

LSD T= 3.46 W= 3.04 TW= 6.09


Water dip 0.84h 7.63h 64.72c 97.88a 61.40c 38.89f 45.23A CaCl 1% 0.84h 17.64g 62.37c 84.50b 63.15c 35.65f 44.03A CaCl 2% 0.84h 8.08h 52.69d 42.56ef 35.18f 23.30g 27.11B CaCl 3% 0.84h 5.56h 47.19de 38.22f 24.34g 36.30f 25.41B

Mean** 0.84F 9.73E 56.74B 65.79A 46.02C 33.53D

Surkh (Year 2)

LSD T= 2.94 W= 3.89 TW= 7.78

Table 29.2: Effect of calcium chloride on PPO activity of “Sufaid” loquat


Water dip 0.52J 8.90ij 69.73ab 64.53bc 59.53bc 35.93g 39.86A CaCl 1% 0.52J 14.69i 27.18h 73.78a 42.05fg 35.46g 32.28B CaCl 2% 0.52J 7.94ij 51.33de 58.66cd 46.22ef 27.53h 32.04B CaCl 3% 0.52i 4.58j 40.41fg 25.87h 27.07h 27.42h 20.98C

Mean** 0.52E 9.02D 47.17B 55.71A 43.72B 31.59C

Sufaid (Year 1)

LSD T= 4.02 W= 3.69 TW= 7.86


(T) 0 2 4 6 8 10 Means* Water dip 0.72j 20.33gh 54.60c 66.93b 79.84a 37.53f 43.33A CaCl 1% 0.72j 5.10j 69.37j 73.77ab 66.70b 33.20f 41.48A CaCl 2% 0.72j 14.88hi 52.12cd 50.33cd 56.63c 31.26f 34.32B CaCl 3% 0.72j 7.75ij 45.73de 32.60f 39.03ef 23.15g 24.83C

Mean** 0.72E 12.01D 55.45B 55.91B 60.55A 31.28C

Sufaid (Year 2)

LSD T= 2.00 W= 3.81 TW= 7.63


147

eight week in control whereas 1% CaCl2 had highest activity (73.77 U/g FW) during the

sixth week. Mayer (1991) reported that PPO becomes active during ripening, senescence

or stress conditions when the membranes are damaged which result in an rise in PPO

activity. White and Broadley (2003) state that CaCl2 applied exogenously stabilized

plant cell walls and protected it from cell wall degrading enzymes. Inhibitory effects of

extracellular concentrations of calcium senescence has been hypothised by Ferguson

(1984) and Leshem (1992). In this study high concentrations (3%) significantly reduced

PPO activity in both cultivars as compared to control treatment while low concentrations

1% and 2% had comparatively higher activity of PPO. This might be due to the fact that

calcium stabilized the membranes against free radical induced lipid oxidation by binding

to the membrane as reported by Klien and Lurie (1994). When analyzing the possible

relationship between the evolutions of BI and PPO activity, strong positive correlation

existed between PPO and BI (r = 0.79, 0.85 for Surkh while r =0.94 and 0.72 for Sufaid

during the first and second years respectively.

3.6.12 Effect on Total Phenolic Content

During the first year, all three concentrations of CaCl2 were statistically similar in

“Surkh” cv. of loquat (Table 30.1), however 1% and 2% CaCl2 treatments differed

significantly from control. 3% CaCl2 retained maximum TP content (24.27 and 30.81

mg.100-1 ) during both years. During the second year, 1% cc was statistically similar to

control whereas 2% and 3% CaCl2 treatments had higher TP content (30.22 mg.100-1 and

30.81 mg.100-1 ) compared to control (28.61 mg.100-1).

Deleted: Appendix

148

A

0

10

20

30

40

50

0 2 4 6 8 10

mg/

100g

FW

C

0

10

20

30

40

50

0 2 4 6 8 10

B

0

10

20

30

40

50

0 2 4 6 8 10


mg/

100g

FW

D

0

10

20

30

40

50

0 2 4 6 8 10



Fig. 26: Effect of calcium chloride agents on total phenolics in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 3.69, B = 3.27, C = 4.23, D = 4.06

149

Table 30.1: Effect of calcium chloride on total phenolics of “Surkh” loquat


Water dip 36.40a 30.90b 27.00bc 23.57cde 19.87ef 15.23g 25.49B CaCl 1% 36.40a 30.20b 29.60b 27.47bc 21.53def 18.93f 27.36AB CaCl 2% 36.40a 30.27b 27.83bc 26.67bc 24.50cd 21.00def 27.78AB CaCl 3% 36.40a 35.17a 29.13b 26.90bc 24.77cd 24.27cd 29.44A

Mean** 36.40A 31.63B 28.39C 26.15D 22.67E 19.86F

Surkh (Year 1)

LSD T= 3.35 W= 1.85 TW= 3.69


Water dip 44.83a 30.63d 29.63def 25.70ghi 22.67ij 18.17ij 28.61AB CaCl 1% 44.83a 30.30de 26.17f-i 23.97hi 16.53l 17.43kl 26.54B CaCl 2% 44.83a 37.17b 31.77cd 26.87e-h 23.07ij 17.60kl 30.22A CaCl 3% 44.83a 34.67bc 31.07d 29.13d-g 25.00hi 20.17jk 30.81A

Mean** 44.83A 33.19B 29.66C 26.42D 21.82E 18.34F

Surkh (Year 2)

LSD T= 3.16 W= 1.63 TW= 3.27

Table 30.2: Effect of calcium chloride on total phenolics of “Sufaid” loquat


Water dip 36.23a 34.60ab 25.60e-i 23.53g-j 19.07jkl 15.80l 25.81B CaCl 1% 36.23a 33.73abc 24.57f-i 22.63g-k 21.10ijk 22.27h-k 26.76AB CaCl 2% 36.23a 32.87abc 29.90cde 26.80d-h 22.47g-k 18.23kl 27.75AB CaCl 3% 36.23a 35.90a 31.10bcd 29.13c-f 27.33d-g 25.20e-i 30.82A

Mean** 36.23A 34.28B 27.79C 25.52D 22.49E 20.38F

Sufaid (Year 1)

LSD T= 4.62 W= 1.89 TW= 4.23


Water dip 39.40a 32.03bc 26.83de 24.67def 22.00fg 16.57h 26.92 ns CaCl 1% 39.40a 33.97b 28.97cd 25.43def 19.60gh 15.53h 27.15 ns CaCl 2% 39.40a 33.27bc 32.27bc 25.27def 23.33efg 19.27gh 28.80 ns CaCl 3% 39.40a 33.57bc 27.33de 23.33efg 21.03fg 21.10fg 27.63 ns

Mean** 39.40A 33.21B 28.85C 24.67D 21.49E 18.12F Sufaid (Y

ear 2) LSD T= 1.82 W= 2.03 TW= 4.06


150

TP content in “Sufaid” cv. decreased in a similar manner during both years of

study (Table 30.2). In the first year, CaCl2 treatments were statistically similar with 3%

CaCl2 having highest TP content (30.28 mg.100-1 ) compared with control (25.18

mg.100-1 ) while no significant difference was observed between treatments during the

second year, however treatment means indicate that control had lowest TP content (26.92

mg.100-1 ) as compared to the other treatments. At the end of tenth week, 3% CaCl2 had

a maximum TP content of 21.10 mg.100-1 compared to 16.57 mg.100-1 in control. TP

content decreased in both years during storage (Fig. 26) in both varieties with maximum

decrease occurring during the first four weeks.

Natural phenolic substrates are separated from PPO by compartmentalization so

that browning does not occur (Marques et al., 1995, Crumiere, 2000). Soluble phenolic

compounds are accumulated mainly in the vacuoles of fruit cells (Macheix et al., 1990).

Tissue browning is associated with membrane deterioration which is lead by senescence

related peroxidation of membrane lipids (Thompson et al., 1987). Ca2+ inhibits stress

induced senescence by maintaining membrane integrity (Gekas et al., 2002). Browning

changes have been correlated with a decrease in total phenolics and a rise in PPO activity

(Cai et al., 2006a).

Our results indicate that, TP content in CaCl2 treatments remained higher than

control. This might be due to fact that CaCl2 helped to maintain cell structures and

controlled deterioration of membranes as reported above which kept the phenolic

substrates separate from PPO.

Deleted: Appendix

151

3.6.13 Effect on Browning Index (BI)

Treatment means in Table 31.1, reveals a significant effect of CaCl2 treatments

on BI of “Surkh” cv. of loquat during storage. Maximum BI (18.72 and 19.86 %) was

recorded in control while lowest BI (10.58 and 14.19%) was observed in 3% CaCl2

during both years. 1% CaCl2 was statistically to control during the first year. Both these

treatments significantly differed with 2% and 3% CaCl2. In the tenth week, control had a

BI of 33.23% while 1%, 2% and 3% CaCl2 treatments had a BI of 37.60, 29.13 and

23.17% respectively. During the second year, 1% and 2% CaCl2 treatments were at par

but differed significantly with control and 3% CaCl2. Control had 41.80% BI compared

with 29.13 and 30.78% in 2% and 3% CaCl2 in the tenth week. Overall BI increased

during storage (Fig. 27).

In “Sufaid” cv. (Table: 31.2), maximum BI was recorded in control which differed

significantly from rest of the treatments, while no significant difference was observed

within CaCl2 treatments during both years (Fig. 27). BI was highest during the eight and

tenth week in all treatments. In the tenth week, 38.73 and 43.57% BI was observed in

control during both years while lowest BI (23.40% and 27.87%) was recorded in 3%

CaCl2.

Membrane deterioration is a consequence of senescence related peroxidation of

membrane lipids (Thompson et al., 1987) and is associated with tissue browning.

Deleted: Appendix

Deleted: Appendix

152

A

0

10

20

30

40

50

0 2 4 6 8 10

Brow

ning

Inde

x (%

)

C

C

0

10

20

30

40

50

0 2 4 6 8 10

B

0

10

20

30

40

50


Brow

ning

Inde

x (%

)

D

0

10

20

30

40

50

0 2 4 6 8 10


Water Dip

CaCl 1%

CaCl 2%

CaCl 3%

Fig. 27: Effect of calcium chloride agents on browning index in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 2.50, B = 5.23, C = 2.74, D = 5.91

153

Table 31.1: Effect of calcium chloride on browning index of “Surkh” loquat


Water dip 0.00k 3.00j 23.17j 25.17def 27.77cd 33.23b 18.72A CaCl 1% 0.00k 1.33jk 19.67g 24.03ef 26.27de 37.60a 18.15A CaCl 2% 0.00k 0.66jk 15.17h 23.32f 26.43de 29.13c 15.79B CaCl 3% 0.00k 0.33jk 7.36i 13.27h 19.37g 23.17f 10.58C

Mean** 0.00F 1.33E 16.34D 21.45C 24.96B 30.78A

Surkh (Year 1)

LSD T= 1.61 W= 1.25 TW= 2.50


Water dip 0.00l 4.66k 15.70i 26.80def 30.17bc 41.80a 19.86A CaCl 1% 0.00l 1.70l 19.10h 23.83fg 26.63def 31.17b 17.07B CaCl 2% 0.00l 0.66l 14.77i 24.23cde 27.33cde 29.57bcd 16.09B CaCl 3% 0.00l 1.33l 10.48j 19.37h 22.97g 30.97b 14.19C

Mean** 0.00F 2.09E 15.01D 23.56C 26.77B 33.38A

Surkh (Year 2)

LSD T= 1.48 W= 2.621 TW= 5.23

Table 31.2: Effect of calcium chloride on browning index of “Sufaid” loquat


Water dip 0.00j 3.00j 21.40fg 26.90cd 32.23b 38.73a 20.38A CaCl 1% 0.00j 1.33j 10.17i 16.00h 27.80c 34.97b 15.04B CaCl 2% 0.00j 0.66j 14.80h 19.03g 24.13def 25.97cde 14.10BC CaCl 3% 0.00j 0.66i 10.43i 14.80h 18.97g 23.40ef 11.38C

Mean** 0.00F 1.41E 14.20D 19.18C 25.78B 30.77A

Sufaid (Year1)

LSD T= 3.02 W= 1.37 TW= 2.74


Water dip 0.00f 4.16f 18.20d 25.83bc 30.33b 43.57a 20.35A CaCl 1% 0.00f 1.00f 11.60e 20.33cd 29.17b 32.20b 15.72B CaCl 2% 0.00f 0.33f 14.83de 20.73cd 26.30bc 28.70b 15.15B CaCl 3% 0.00f 1.23f 15.23de 17.43de 25.70bc 27.87b 14.58B

Mean** 0.00E 1.68E 14.97D 21.08C 27.88B 33.08A Sufaid (Y

ear 2) LSD T= 2.41 W= 2.53 TW= 5.91


154

Dipping treatments are mainly employed to prevent oxidation of polyphenols by

PPO, which is a secondary oxidation process. Polyphenols are located in the vacuole and

PPO in the plastids and mitochondria of intact cells (Murata et al., 1997). Oxidative

membrane injury is the primary process that allows the mixing of the normally spatially

separated enzyme (PPO) and oxidizable substrates (polyphenols), which lead to browning

(Hodges, 2003). Calcium dips have been used to enhance membrane stability, slow down

senescence and enhance retention of membrane integrity (Poovaiah, 1988; Picchioni et

al., 1995) and have shown to delay membrane deterioration in cabbage (Cheour et al.,

1992) and apples (Picchioni et al., 1995).

Symptoms of internal breakdown often referred to as flesh browning have been

observed in peach fruits after extended cold storage. Similar indications in other fruits

have been related to low calcium content (Hewajulige et al., 2003; Thorp et al., 2003).

High calcium concentrations decreased flesh browning which have been related directly

to the calcium content in other fresh fruits (Hewajulige et al., 2003). Therefore, calcium

dipping treatments are believed to decrease flesh browning in fruits. Physiological

disorders in low storage temperatures may be associated with the calcium content

(Hewajulige et al., 2003; Thorp et al., 2003). Similar effect of calcium salts have been

observed for fresh-cut fruits (Gorny et al., 2002; Luna-Guzman and Barrett, 2000),

where the enzymatic flesh is a consequence of different metabolic pathways (Manganaris

et al., 2007).

Rosen and Kader (1989) reported that 1% CaCl2 dip and 0.5% O2 atmosphere

reduced softening and browning disorder in ’Bartlett’ pear slices. Postharvest application

155

of 4% calcium chloride on fruits of Pathernakh pear, cultivar of Asian pear proved to be

the an effective treatment in reducing core browning up to 75 days of storage, as

compared to water dip control which had a 30% level of core browning (Mahajan and

Dhatta, 2004). This study also indicates that CaCl2 treatments had a significant effect on

decreasing the BI of loquat as compared to control. This could be due to the fact that

calcium helped to maintain membrane stability as mentioned by Poovaiah (1988) and

Picchioni et al. (1995). Thus our results support the findings of the above mentioned

scientists.

3.6.14 Effect on Relative Electrical Conductivity (REC)

Highest REC (51.26% and 50.14%) in “Surkh” cultivar of loquat during both

years was recorded in control (Table 32.1). Both higher concentrations of CaCl2 had

lower REC values as compared to 1% CaCl2 during both years. Relative electrical

conductivity gradually increased during storage reaching its maximum at the end of

tenth week. In control REC reached upto 67.63% and 71.47% at the end of tenth week

during both years, while in other treatments, highest REC (59.70 and 60.7%) during

both years was recorded in 1% CaCl2 during the tenth week. In control, REC changes

increased during the sixth week (57.43%) reaching a maximum at the end of tenth week.

In “Sufaid” cultivar highest REC was also recorded in control during both years

(Table 32.2) and differed significantly from other CaCl2 treatments. During both years,

2% and 3% CaCl2 had the significantly lower REC values compared to control. REC

gradually increased towards the end of storage period throughout both years

(Fig. 28). In control REC reached upto 68.33% in the sixth week and was 67.63% at the

Deleted: Appendix

Deleted: Appendix

156

A

0

20

40

60

80

100

0 2 4 6 8 10

Rel

ativ

e El

ectri

cal C

ondu

ctiv

ity (%

) C

0

20

40

60

80

100

0 2 4 6 8 10

B

0

20

40

60

80

100

0 2 4 6 8 10


Rel

ativ

e El

ectri

cal C

ondu

ctiv

ity (%

)

D

0

20

40

60

80

100



Fig. 28: Effect of calcium chloride agents on relative electrical conductivity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 5.65, B = 4.90, C = 6.73, D = 6.0

157

Table 32.1: Effect of calcium chloride on relative electrical conductivity of “Surkh” loquat


(T) 0 2 4 6 8 10 Means* Water dip 29.83g 38.80f 50.33de 55.63b-e 65.63a 67.30a 51.26A CaCl 1% 29.83g 40.23f 49.33e 55.07b-e 57.97bc 59.70b 48.69B CaCl 2% 29.83g 39.77f 43.23f 43.33f 53.97b-e 56.13bcd 44.38C CaCl 3% 29.83g 38.93f 40.80f 41.70f 51.77cde 55.37b-e 43.07C

Mean** 29.83E 39.43D 45.92C 48.93B 57.33A 59.63A

Surkh (Year 1)

LSD T= 2.11 W= 2.82 TW= 5.65


(T) 0 2 4 6 8 10 Means* Water dip 25.70j 39.33gh 46.83ef 57.43bc 60.10b 71.47a 50.14A CaCl 1% 25.70j 34.13hi 44.33fg 51.00de 59.57bc 60.70b 45.91B CaCl 2% 25.70j 35.53hi 39.27gh 45.77ef 46.50ef 54.77cd 41.26C CaCl 3% 25.70j 31.13i 41.60 43.20fg 44.63f 50.10de 39.39C

Mean** 25.70F 35.03E 43.01D 49.35C 52.70B 59.26A

Surkh (Year 2)

LSD T= 2.35 W= 2.45 TW= 4.90

Table 32.2: Effect of calcium chloride on relative electrical conductivity of “Sufaid”

loquat


Water dip 30.30k 38.77ij 46.73fgh 68.33a 65.37ab 67.63ab 52.86A CaCl 1% 30.30k 47.80e-h 52.50def 54.73cde 54.53cde 56.40cd 49.38B CaCl 2% 30.30k 35.27jk 40.50hij 42.73hi 47.53e-h 60.57bc 42.82C CaCl 3% 30.30k 45.17f-i 51.60d-g 44.53ghi 54.90cde 66.87ab 48.89B

Mean** 30.30F 41.75E 47.83D 52.58C 55..58B 62.87A

Sufaid (Year 1)

LSD T= 1.74 W= 2.75 TW= 6.73


Water dip 26.63j 41.93fgh 41.37gh 57.77bc 61.07b 71.73a 50.08A CaCl 1% 26.63j 45.07fgh 48.63def 52.87cde 54.90bcd 53.43cde 46.92A CaCl 2% 26.63j 33.73i 43.00fgh 42.57fgh 44.13fgh 57.83bc 41.32B CaCl 3% 26.63j 30.03ij 40.40h 48.00efg 48.67def 51.93cde 40.94B

Mean** 26.63E 37.69D 43.35C 50.30B 52.19B 58.73A Sufaid (Y

ear 2)

LSD T= 3.39 W= 3.00 TW= 6.00


Formatted

158

end of tenth week during the first year, while highest REC values in other treatments was

recorded in 3% CaCl2 (66.87) during the tenth week. During the second year, REC in

control was highest in the tenth week (71.73%) as compared to other treatments, while in

CaCl2 treatments it remained less than 60%.

Cell membranes regulate ions and metabolites in and outside the cell by selective

transport and maintain the compartments of cells for water retention (Rubinstein, 2000).

Disruption in cell membrane lead to senescence (Itzhaki et al., 1990). Reports on

postharvest physiology propose that Ca may have a role in controlling membrane

stability and senescence of plant cells (Leshem, 1992; Torre et al., 1999; Rubinstein,

2000). Supplemental calcium may lower senescence by delaying physiological events

connected with senescence including lower water uptake, excessive water loss and

decrease in fresh weight (Nan, 2007). Decreased electrolyte leakage by calcium

application increases the cell wall integrity and stability (Mortazavi et al., 2007).This

study shows that calcium treatments had a positive effect on REC. 3% CaCl2 had the

lowest decrease in REC in both cultivars during both years as compared to control. The

lower REC might be due to less disruption in the plasma lemma membranes as reported

by Meng et al. (2009) and the increased cohesion of cell membranes (Demarty et al.,

1984).

Pearson linear correlation revealed highly significant correlations coefficients

(P < 0.05), r = 0.93, 0.97 for Surkh and r =0.89 and 0.87 between EC and browning

index for Sufaid during the first and second years respectively.

159

3.7 CONCLUSION

1 % CaCl2 treatment did not show significant effect on quality parameters

compared with control treatment

2% CaCl2 had high firmness, RSA, SOD, CAT activity and low PPO,

POD activity and EC while in addition to the above parameters 3%

CaCl2 retained maximum firmness, TSS, TP content, reducing, non

reducing and total sugars, lowest BI and weight loss up to 4-5 weeks in

both cultivars

160

Chapter 4

EFFECT OF ANTI BROWNING AGENTS ON THE KEEPING QUALITY OF LOQUAT FRUIT

4.1 ABSTRACT

Browning is major problem of loquat fruit which reduces its shelf life. Different

anti browning agents are used in food products to control undesirable browning. A study

was conducted to evaluate the effectiveness of two naturally occurring and generally

regarded as safe (GRAS) chemicals, namely ascorbic acid (AA) and citric acid (CA) to

assess their antibrowning potential on loquat fruit during a ten week storage period at

4˚C in a cold store. Dipping treatments for two minutes, at three concentrations (250

mg/l, 500 mg/l and 750 mg/l) of both AA and CA were applied on two local cultivars

(Surkh and Sufaid) of loquat fruit, harvested at mature ripe stage. The fruit were sorted,

clipped and washed on the same day. After applying the dipping treatments fruit was

stored in corrugated soft board cartons in a cold store at 4˚C, for ten weeks. Changes in

weight loss, firmness, total soluble solids, browning index, ascorbic acid, titratable

acidity, electrolyte leakage, total phenolics, polyphenol oxidase, superoxidase dismutase,

peroxidase, catalase and total antioxidants were studied. Higher concentrations of

Ascorbic acid held fruit quality much better then citric acid for up to 4-5 weeks. Ascorbic

acid content of both cultivars was not effected by antibrowning agents during both year,

however all treatments differed significantly from control. Higher concentrations of both

Ascorbic acid and Citric acid reduced browning significantly. Reducing, non reducing

and total sugars were not effected by anti browning agents in both cultivars. Higher

concentrations of both Ascorbic acid and Citric acid reduced browning significantly.

161

4.2 INTRODUCTION

Different types of chemicals, acidulants and reducing agents are used to control

enzymatic browning in fruits. CA and AA are used widely due to their antibrowning

properties in food processing (Son et al., 2001). Ascorbic acid (AA), a water soluble

antioxidant and is used as an inhibitor of browning reactions (Freedman and Francis,

1984). Because of its non detectable flavor and non corrosiveness it is widely used as a

food preservative in juices and to improve nutritional quality of food products. It also has

a medicinal value. It acts as a reducing agent and is oxidized during the process

(Padayatty et al., 2003). It directly removes harmful free radicals by the forming

ascorbyl radicals (Yamaguchi et al., 1999). It reduces the o-quinones generated by PPO

enzymes, back to the phenolic substrates (Robert et al., 2003). Citric acid is used in food

products as a preservative, acidulant, or flavourable agent. It acts as an antioxidant

synergist and controls growth of food spoilage microorganisms (Banwart, 1989;

Beuchat and Golden, 1989). Browning is a major problem in loquat which makes it

perishable with a short shelf life. Both these anti browning agents were used to evaluate

their effectiveness in reducing browning and to study its effectiveness in enhancing its

shelf life.


4.3.1 Chemicals For Extending Post Harvest Life

Various kinds of chemicals, reducing agents and acidulants are used as additives

to preserve foods which mainly serve to control enzymatic browning. The use of

chemicals is however, restricted to compounds that are nontoxic, and that do not

162

adversely affect taste and flavor (McEvily et al., 1992; Saper, 1993). Chemicals used as

food additives are known to decrease the disease pressure on harvested commodities

(Eckert, 1991; Smilanick et al., 1999). Organic acids classified as Generally Regarded As

Safe (GRAS) have been extensively used on foods for years (Niranjala and Karunaratne,

2001).

4.3.2 Ascorbic Acid

Ascorbic acid (AA) or vitamin C is a water soluble antioxidant known to be

important to health (Davey et al., 2000). It is the most widely used phenolase suppressor

because it does not impart any flavor at the concentration used and it does not corrode

metals. It also has a nutritive value (vitamin C). All known physiological and

biochemical actions of vitamin C are due to its ability to act as a reducing agent. Ascorbic

acid donates two electrons from a double bond between the second and third carbons of

the 6-carbon molecule. However, during this reaction, vitamin C itself is oxidized

(Padayatty et al., 2003).

AA exists mostly in reduced form in leaves and chloroplasts (Smirnoff, 2000). Its

capability to donate electrons in various enzymatic and non-enzymatic reactions makes

AA the main reactive oxygen species (ROS) detoxifying agent in aqueous phase

(Blokhina et al., 2003).

AA seizess harmful free radicals directly or indirectly, within the live cells. It

can directly scavenge superoxide, hydroxyl radicals and singlet oxygen and reduce H2O2

to water via ascorbate peroxidase reaction (Noctor and yamaguchi, 1998). It plays an

163

essential role in capturing hydrogen peroxide and protects thiol groups of enzymes and

proteins from oxidation (Foyer, 1993). Ascorbic acid acts against reactive O2 species in

concert with other antioxidants such as glutathione and α-tocopherol, in a system

referred to as the ascorbate–glutathione cycle [fig 29(Jimenez et al., 1997)]. The

repressing action of AA is also due to the reduction of the o-quinones produced by PPO

enzymes, back to the phenolic substrates (Robert et al., 2003).

Fig 29: The ascorbate-glutathione cycle (Noctor and Foyer, 1998)

Ascorbic acid and its derivatives are used in many foods for various purposes.

They are added to foods, including fruit juices, to enhance the nutritional quality, avoid

enzymatic browning (Freedman and Francis, 1984) and to help retain firmness in fruits.

Weight loss was greatly reduced in fresh okra dipped in an aqueous solutions

containing 250 and 500 mg/l ascorbic acid and stored at 2°C for 20 days (Aderiye, 1985).

164

Both citric and ascorbic acid were effective in improving the quality, shelf life and

delaying of browning reaction of the artichoke heads stored in closed polyethylene bags

after 2 or 4 weeks (Lattanzio et al., 1989). Post-harvest dipping in 150 and 300 mg/l

ascorbic acid solution lowered over-ripening, enhanced TSS but did not affect acidity and

ascorbic acid content in ber (Ziziphus mauritiana Lamk.) during storage (Siddiqui and

Gupta, 1995). Gorny et al. (1999) reported that 20000 mg/l ascorbic acid + 10000 mg/l

calcium lactate post cutting dip did not significantly effect cut surface browning and

tissue softening in ‘Carnival’ peach slices. Ascorbic acid and its compounds have been

used in many on fruits in different concentrations ranging from 5000 mg/l to 40000 mg/l.

The anti-browning properties of ascorbic acid have been proved in many processed fruits

under a different conditions (Soliva et al., 2002). Esparza et al. (2005) observed that

overall acceptability and flavor quality of green leaf lettuce was highest when treated in

a 10000 mg/l ascorbic acid solution for two minutes and stored at 5 °C for up to 14

days in sealed polyethylene bags. Elez et al. (2005) reported that 200 mg/l ascorbic acid

reduced oil rancidity processes during 12 week storage of minimally processed avocado

purees.

4.3.3 Citric Acid

Citric acid is a GRAS-listed compound and is broadly used as a preservative,

acidulant, or flavoring agent in many foods and beverages (Pao and Petracek, 1997).

Citric acid is a phenolase Cu-chelating agent and inhibits polyphenol oxidase (PPO) due

to its property to act as a chelating agent (Jiang et al.,1999). It is also an antioxidant

synergist and anti-microbial agent (Christopher et al., 2003). Citric acid is believed to be

165

useful in repressing superficial pH of cut fruits (Robert et al., 2003). The significant

effect of citric acid in limiting the development of food spoilage and pathogenic micro-

organisms is widely accepted (Banwart, 1989; Beuchat and Golden. 1989)

Application of citric acid avoided browning of apple slices and extended its

shelf life (Santerre et al., 1988). Vincenzo et al. (1989) observed that both citric and

ascorbic acid were effective in improving the quality, as well as the shelf life, of the

stored artichoke heads and by using either of the acids, an important delay of browning

reaction could be noticed in the treated plant material. Treating slices of Carambola

fruit with 10000 or 25000 mg/l citric acid before packaging effectively limited

browning (Weller et al., 1997). Maximal shelf life extension in citrus with 5000 mg/l

citric acid dipping treatment for 4°C storage (Pao and Petacek, 1997). Brenna et al.

(2000) reported that fresh sliced mushrooms dipped for 10 minutes in citric acid

solutions and stored at 4 oC for up to 19 day checked the growth of pseudomonas

bacteria and enhanced the keeping quality when compared to control (water soaked)

slices. Niranjala and Karunaratne (2001) observed that 500 mg/l citric acid or 1000

mg/l ascorbic acid significantly reduced disease incidence in banana. Citric acid at

10000 mg/l reduced growth of black speck and extended shelf life from 10 days of the

control to 14 days at 5 °C in Chinese Cabbage (Kim and Klieber, 1999). Lopez (2002)

reported that the best treatment for the storage of avocado halves was a 10000 mg/l

ascorbic acid and 10000 mg/l citric acid solution at pH 5 and 7 °C. Severini et al.

(2003) found that citric acid or addition of some other antioxidants such as ascorbic

acid, sodium or potassium bisulphate prevented browning by inhibiting PPO or

preventing tmation of melanins. Citric acid was found to be the most efficient

166

antibrowning agent during storage in air at 30 °C and inhibited browning to 36% after

four weeks in a glucose–lysine model (Kwak and Seong, 2005). Assimopoulou et al.

(2005) observed that highest antioxidant activity in sunflower oil was obtained where

Pistacia lentiscus resin (500 mg/l + citric acid 300 mg/l), followed by P. lentiscus resin

(100 mg/l + citric acid 200 mg/l) was used.

4.3.4 Peroxidase (POD)

Flesh browning is the main problem which is related to the deterioration of loquat

fruits and is linked with phenol-related metabolic enzymes POD and PPO (Loaiza and

Saltveit, 2001). POD (EC 1.11.1.7) also catalyzes the breakdown of H2O2 by liberating

free radicals instead of oxygen as in case of catalase (Burris, 1960). The peroxidases

mostly occur in cell walls where they use H2O2 to generate phenoxy compounds which

are polymerized to yield compounds such as lignin (Greppin et al., 1986). Various types

of peroxidases are found in plants; unlike catalase, and these require a substrate (R) for

catalysis:

2H2O2 2H2O + O2 (CAT)

H2O2 + RH2 2H2O + O2 (POD)

The peroxidases are involved in several metabolic plant processes such as the

catabolising auxins, forming bridges between cell wall components and oxidizing the

cinnamyl alcohols prior to their polymerization during formation of suberin and lignin

(Quiroga et al., 2000; Lejaa et al., 2003). Polyphenol oxidase (PPO) and peroxidases

167

(POD) are the main enzymes responsible for quality loss due to Phenolic degradation

(Francois and Espin, 2001). Peroxidases appear to present in all part of the living cell in

response to stress and take part in different biochemical functions in higher plants

(Gaspar et al., 1981).They are a class of copper proteins and exist in bacteria to mammals

(Robb, 1984.). The are 3 kinds of proteins which are associated with PPO’s mamely

laccase, catechol oxidase, and cresolase (Yelena et al., 1996).

Activated oxygen species in plant cells may react with unsaturated fatty acids and

cause peroxidation of membrane lipids in plasmalemma or intracellular organelles. This

damage causes desiccation, leakage of cellular contents and cell mortality in plant tissue

(Scandalios, 1993b). The peroxidation of plasmalemma causes leakage of phenolic

compounds from the vacuole, facilitating the polyphenol oxidase reaction.

Aydin and Kadioglu (2001) observed an increase in POD activity during fruit

maturation and senescence. El-hilali et al. (2003) reported POD specific activity in

mandarin increased continuously during a 30 day storage period at 4 °C, with least

changes in fruit treated with 1% Ca(NO3)2.4H2O. Setha et al. (2000) also observed

similar results in papaya during a 30 day storage at 5 °C and 15 °C.

4.3.5 Phenolic Compounds And Polyphenol Oxidase (PPO)

Phenolic compounds belong to an important class of naturally occurring

antioxidants, because of their diverse nature wide distribution (Sonia and Chaves, 2006).

They are bioactive substances synthesized as secondary metabolites by all plants

connected to diverse functions such as nutrient uptake, protein synthesis, enzyme activity,

168

photosynthesis, and as structural components (Robbins, 2003). They have both chemical

and biological characteristics. Positive impacts of phenolic compounds on human health

include inhibition of oxidation of low-density protein thereby reducing the risk of heart

disease. Anti-inflammatory and anticarcinogenic properties of polyphenolic compounds

have also been reported ( Kang et al., 2005).

Polyphenolics are synthesized by numerous plants as secondary metabolites. The

beneficial effects from fruits and vegetables have been ascribed to natural antioxidants

such as anthocyanins and polyphenolics (Kaur and Kapoor, 2001). Polyphenolic

compounds are reported to have diverse biological effects, including antioxidant activity,

antimutagenic, antitumor and antibacterial characteristics (Shui and Leong, 2002). More

than 8000 naturally occurring phenolic compounds with diverse structural configurations

have been isolated from natural sources (Robbins, 2003; Devanand and Mukhopadhyay,

2006).

Polyphenols play an important role in preventing oxidation of not only foods but

also biomolecules in human body (Ramassamy, 2006). Polyphenolics behave as

antioxidants, mainly due to the reactivity of the hydroxyl substituents in the aromatic

ring. They are capable of reducing the formation of free-radical formation by eliminating

free radicals (Hashim et al., 2005) and many electrophiles, for chelating metallic ions,

trend of self-oxidation and ability for regulating the enzyme activity of some cells

(Robards et al., 1999; Pyo et al., 2004). Phenolic compounds have a strong antioxidant

capacity in quenching and/or neutralizing free radicals by donating hydrogen to reactive

free radicals (Karakaya et al., 2001; Fernandez-Pachon et al., 2004). Phenolic compounds

169

also protect the delicate cell structures from the harmful effects of UV radiation by acting

as filters. These filters are generally in the form flavonols present in the fruit skin

(Hamauzu, 2006).These compounds impart vital sensory attributes in foods such as

color, astringency, and bitterness along with other possible nutritional properties.

Phenylalanine acts as a precursor in the biosynthesis of phenolic compounds in

higher plants. The most important enzyme in the biosynthesis of phenolics is

phenylalanine ammonialyase (PAL) which catalyses the deamination of phenylalanine to

form trans-cinnamic acid which is further transformed to 4- coumaric acid by cinnamate

4-hydroxylase. During the process hydroxycinnamic acids and certain coenzyme A

esters are formed which are integral elements some other groups of phenolic compounds

which include lignin, hydroxycinnamate esters, flavonoids, benzoic acids and stilbenes

(Hamauzu, 2006).

Phenolic acids may exist in multiple forms as free, esterified, glycosylated, or

polymerized and may coexist as complexes with proteins, carbohydrates, lipids, or other

plants components (Naczk and Shahidi, 2004). Basically, they have one common

structural feature, which is a phenol (an aromatic ring possessing at least one hydroxyl

substituent) and are divided into two categories that include polyphenols and simple

phenols based on the number of phenol subunits present. Polyphenolics have at least two

phenol subunits and tannins have at least three phenol subunits. Phenolic acid is a phenol

that has one carboxylic acid functional group and is related to color, sensory quality, and

antioxidant capacity of foods (Robbins, 2003). Phenolics having three or more phenol

subunits and having the ability to precipitate proteins are known as “tannin” and are

170

categorized as either “condensed” or “hydrolyzable” tannins (Hagerman, 2002; Robbins,

2003).

4.3.6 Role of Phenolics In Enzymatic Browning

Enzymatic browning is the most common defect appearing in horticultural

products (Shewfelt, 1994). which is caused mainly by polyphenol oxidase (PPO) in fruits

and vegetables. It is an undesirable reaction which causes bitterness, deterioration in the

quality and loss of nutrients (Sanchez and Solano, 1997). Browning can occur by

mechanical damage that unites polyphenol oxidase and phenolic compounds to form

brown pigment (Wills et al., 1982). Three different causes of browning can be cited as

follows:(i) various technological processes which constitute the main cause and include

wounding (such as cuts, peels), crushing, extraction, freezing, freeze drying; (ii) some

disorders which may occur during cold storage; and (iii) physiological evolution related

to the maturation (Marqués et al., 1995; Crumiere, 2000).

Enzymatic browning is also known as the most important colour reaction that

affects fruits and vegetables. Browning intensity is regulated by the quantity of active

forms of the enzyme and phenolic content present in the fruit tissue (Robert et al., 2003).

However, in certain instances, such as in certain dried fruits including prunes, black

raisins, black figs, dates as well as in the manufacturing of tea, coffee and cocoa, PPO

activity is essential to the manufacturing processes; it contributes to the desirable color

and flavor of the products and thus improves their sensory properties (Walker, 1995).

Enzymatic browning has a key role in the "fermentation" stage of black tea

manufacturing (Zawistoski et al., 1991). The beverage quality of coffee has been shown

171

to be related to the level of PPO activity in green coffee beans and PPO has a key role in

the development of the color of processed cacao beans which contain large amounts of

phenolic constituents such as epicatechin (Walker,1995).

Polyphenol oxidase (EC 1.10.3.1) is primary enzyme which causes enzymatic

browning in fruits. Phenolic compounds are catalysed by this enzyme, and is also known

as phenoloxidase, monophenol oxidase, phenolase, tyrosinase and diphenol oxidase

(Madinez and Whitaker, 1995; Crumiere, 2000.).

Two kinds of enzymes are classified under the trivial name of PPO. Based on

substrate specificity, Enzyme Nomenclature (1992) has designated these two kinds as (i)

diphenol oxidases, catechol oxidases or diphenol oxygen oxidoreductases (EC 1.10.3. l),

the enzymes which catalyze two distinct reactions (Fig. 30 ), including the hydroxylation

of monophenols to o-diphenols (reaction 1) followed by the oxidation of o-diphenols to

o-quinones (reaction 2); and (ii) laccases, or p-diphenol oxygen oxidoreductase (EC

1.10.3.2), the enzymes that oxidize o-diphenols as well as p-diphenols to the

corresponding quinines.

The nomenclature of PPO is somewhat confusing because besides the two types

of PPOs designated as EC 1.10.3.1 and EC 1.10.3.2, a third one exists, designated as EC

1.14.18.1 (Enzyme Nomenclature, 1992); it is referred to as monophenol

monooxygenase, cresolase or tyrosinase and corresponds to the same enzyme as EC

1.10.3.1 and catalyzes the hydroxylation of monophenols (Crumiere, 2000).

172

Fig. 30 : Reactions catalyzed by polyphenol oxidases.

(a) Hydroxylation of monophenol to o-diphenol. (b) Dehydrogenation of o- diphenol to o-quinone.

PPO is a copper enzyme which catalyzes the oxidation of o-diphenols to

o-quinones (diphenolase, catecholase activity) in the presence of oxygen (Ding et al.,

1998) which is the first step in polymerizing phenolics into o-quinones. The primary

products, o-quinones, are yellowish, reactive and unstable compounds. They can

interreact with each other to yield polymers of high molecular weights, form

macromolecular complexes with amino acids or proteins, and oxidize compounds of

lower oxidation-reduction potentials (Vamos-Vigyazo, 1995). Further non-enzymatic

reactions with oxygen lead to additional reactions to give relatively dark, insoluble

polymers referred to as melanins (Whitaker and Lee, 1995). These melanins act as

barriers and possess antimicrobial properties and prevent infection or damage to plant

tissues. The color of pigments differs widely in hue and intensity, depending on the

Deleted: The nomenclature of PPO is somewhat confusing because besides the two types of PPOs designated as EC 1.10.3.1 and EC 1.10.3.2, a third one exists, designated as EC 1.14.18.1 (Enzyme Nomenclature, 1992); it is referred to as monophenol monooxygenase, cresolase or tyrosinase and corresponds to the same enzyme as EC 1.10.3.1 and catalyzes the hydroxylation of monophenols (Crumiere, 2000).¶

Deleted: rn

Deleted: 81

173

phenols from which they originate and the environmental factors of the oxidation

reactions (Nicolas et al., 1994).

PPO normally becomes active during ripening, senescence or stress conditions

such as membrane damage, resulting in increased PPO activity (Mayer, 1991). Once cell

walls and cellular membranes are disrupted, enzymatic oxidation starts at much faster

rates (Madinez and Whitaker. 1995). Andres et al. (2002), reported that PPO activity was

reduced by two-thirds in apple cubes treated with ascorbic acid and citric acid. Acids,

including malic, phosphoric or citric acid, can retard PPO activity by lowering pH and /

or copper chelation in food products (Richardson and Hyslop, 1985).

Among the other compounds having anti browning properties include ascorbic

acid and its derivatives, sulphites, citric acid, oxalic acid and thiol compounds such as

cysteine. Certain anti browning agents also have antioxidant properties (Altunkaya and

Gokmen, 2008). Browning can also be inhibited using low temperature storage,

atmospheric modification and careful handling (Shewfelt, 1994).

4.3.7 Substrates of PPO

Fruits and vegetables contain a wide variety of phenolic compounds with the most

commonly found being benzoic acids, cinnamic acids, flavonols, tannin "precursors" and

anthocyanidins; however only few compounds act as PPO substrates because the enzyme

does not act on glycosides. The most important natural substrates are catechins, cinnamic

acid esters including chlorogenic acid and its isomers, 3,4- dihydroxyphenyl alanine &-

DOPA) and tyrosine (Macheix et al., 1990, Crumiere, 2000).

174

4.3.8 Sources of PPO

PPOs are found in most plant tissues including apples (Harel et al., 1964), grapes,

pears (Rivas and Whitaker, 1973), potatoes (Craft, 1966) and tea (Zawistoski et al.,

1991), as well as certain seeds such as cocoa and coffee, in microorganisms including

bacteria and fungi (Vamos-Vigyazo, 1981) and some higher animals such as insects

(Sugumaran, 1988), arthropods, mammals and humans (Witkop, 1985). The localization

of PPO in plant cells depends on the species, age and on maturity of fruits and vegetables.

In addition, in uncut or not damaged fruits and vegetables, the natural phenolic substrates

are separated from PPO by compartmentalization so that browning does not occur

(Marques et al., 1995, Crumiere, 2000).

The polyphenols concentration in loquats is very high and approximately 60% of

it in ripe fruit consists of chlorogenic acid and neochlorogenic acid (Ding et al., 1999).

Ascorbic acid is a commonly used as a natural PPO inhibitor (Gonzalez-Aguilar et al.,

2005). Pizzocaro et al. (1993) reported that a 5 min dip in a solution containing a

mixture of 10000 mg/l ascorbic acid and 2000 ppm citric acid resulted in 90–100%

inhibition of PPO. Andres et al. (2002) reported that when ascorbic acid and citric acid

was applied to apple cubes it reduced PPO activity by two-thirds. Small amounts of citric

acid may enhance PPO activity, but at 21000 mg/l or higher concentrations it markedly

reduced PPO activity (Jiang et al., 2004).

Deleted: rn

Deleted: mas

Deleted: 81

Deleted: 95

Deleted:

175


Fruit of two loquat cultivars were harvest as described in section 2.5. Ascorbic

acid and citric acid dipping treatments were applied to freshly harvested loquat fruit for

two minutes in the following concentrations:

1. Distilled water (control)

2. Ascorbic acid 250 mg/l



5. Citric Ascorbic acid 250 mg/l



Sampling and analysis of the following parameters was done as described in

section 2.4.

• Weight Loss

• Fruit Firmness

• Total Soluble Solid

• Sugars

Reducing sugars

Total Sugars

Non- Reducing Sugars

176

• Titratable Acidity

• Total Soluble Proteins

• Superoxide Dismutase (SOD) Assay

• Catalase (CAT) Assay

• Peroxidase (POD) Assay

• Ascorbic Acid Content (Vitamin C)

• Radical Scavenging Activity

• Polyphenol Oxidase (PPO) Assay

• Total Phenolic Compounds

• Browning Index

• Relative Electrical Conductivity


The experiment layout and analysis was done as described in section 2.5.

Deleted: EXPERIMENTAL DESIGN AND

177


4.6.1. Effect on weight Loss

In Surkh cv. of loquat, control, AA 250 mg/l, CA 500 mg/l and CA 750 mg/l all

had significantly higher weight loss (3.23%, 3.31%, 3.05% and 3.17%) whereas

minimum losses (2.28% and 2.39%) were recorded in AA 500 mg/l and AA 750 mg/l

(Table 33.1). Maximum average weight loss (3.84% and 3.75%) were recorded during

the sixth and eight week. Highest loss (6.15%) was observed in control during the sixth

week followed by 5.11% in AA 250 mg/l during the tenth week. During the second

year, all treatments had higher losses and all were statistically similar in effect except AA

500 mg/l and AA 750 mg/l which differed significantly with the rest and had lower losses

in weight (Fig. 31). Maximum average loss in weight (8.61%) was recorded in control

during the sixth week. Storage period means show that weight loss was high during the

fourth and sixth weeks.

In “Sufaid” cv. of loquat control had maximum loss in weight (4.07%) followed

by AA 750 mg/l, CA 500 mg/l and CA 750 mg/l in both years. Lowest loss (2.99%) was

recorded in AA 250 mg/l (Table 33.2). The highest average loss in weight (4.51%) was

recorded during the fourth week in all treatments. During the second year, control, AA

750 mg/l and CA 250 mg/l were statistically similar in effect. Highest losses in weight

were recorded during the fourth and sixth weeks. Maximum loss (6.44%) was recorded in

CA 750 mg/l during the fourth week.

Deleted: Appendix

Deleted: Appendix

178

A

0

2

4

6

8

0 2 4 6 8 10

Wei

ght L

oss

(%)

C

0

2

4

6

8

0 2 4 6 8 10 B

0

2

4

6

8

10

0 2 4 6 8 10

Storage periods (w eeks)

Wei

ght L

oss

(%)

D

0

2

4

6

8

0 2 4 6 8 10



Fig. 31: Effect of antibrowning agents on weight loss in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.38, B = 0.33, C = 0.37, D = 1.09

AA = Ascorbic acid, CA = Citric acid

179

Table 33.1: Effect of anti browning agents on weight loss percentage of “Surkh” loquat

Storage Period – weeks (W) Treatment (T) 0 2 4 6 8 10 Means

Water dip 0.00q 2.28mno 3.01l 6.15a 4.96bc 2.97l 3.23A AA 250 mg/l 0.00q 2.40m 4.97ab 3.29jkl 4.11efg 5.11a 3.31A AA 500 mg/l 0.00q 1.49p 2.25mno 3.63hij 4.44de 1.87op 2.28D AA 750 mg/l 0.00q 1.93no 3.55ijk 3.68hij 2.8l 2.32mn 2.39D CA 250 mg/l 0.00q 2.00mno 2.23mno 4.86abc 3.54ijk 4.04e-h 2.78BC CA 500 mg/l 0.00q 2.33mn 3.55ijk 3.86ghi 4.25d-g 4.33def 3.05AB CA 750 mg/l 0.00q 2.93l 4.63bcd 4.47cde 3.95f-i 3.05l 3.17A

Mean* 0.00D 2.34C 3.64AB 3.84A 3.75A 3.29B

Surkh (Year 1)

T = 0.28 W = 0.55 TW = 0.38


Water dip 0.00o 2.57j-m 3.37f-k 8.61a 5.97b 3.46f-k 4.00A AA 250 mg/l 0.00o 2.72j-m 4.73b-e 4.63cde 4.19d-h 5.8a 3.69A AA 500 mg/l 0.00o 1.40n 2.78i-m 3.63e-j 4.21d-h 1.43n 2.24B AA 750 mg/l 0.00o 1.78mn 3.71e-j 4.06e-h 3.65e-j 3.07h-l 2.71B CA 250 mg/l 0.00o 3.27g-l 3.34f-k 5.81ab 5.38a-d 3.61e-k 3.57A CA 500 mg/l 0.00o 2.15lmn 4.44c-g 6.36a 4.71b-e 4.59cde 3.70A CA 750 mg/l 0.00o 4.51c-f 6.32a 4.47c-g 3.95e-i 3.05h-l 3.72A

Mean* 0.00E 2.91D 4.40AB 4.66A 4.26B 3.44C

Surkh (Year 2)

T = 0.49 W = 0.38 TW = 0.33

AA= Ascorbic acid CA= Citric acid *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)

180

Table 33.2: Effect of anti browning agents on weight loss percentage of “Sufaid” loquat


Water dip 0.00t 2.92def 5.64b 6.14a 3.95c 5.76ab 4.07A AA 250 mg/l 0.00t 4.13fgh 4.27efg 3.24j-m 4.53c-f 1.77r 2.99C AA 500 mg/l 0.00t 2.12pqr 4.65cde 4.13fgh 2.55nop 2.05qr 2.58D AA 750 mg/l 0.00t 3.44jk 5.00bc 4.50def 4.56c-f 2.05qr 3.26BC CA 250 mg/l 0.00t 1.14s 3.97ghi 4.12fgh 2.94lmn 1.98oqr 2.36D CA 500 mg/l 0.00t 3.55ij 4.86bcd 3.67hij 5.14b 3.30j-m 3.42B CA 750 mg/l 0.00t 3.34jkl 5.99a 4.75b-e 4.15fgh 2.46opq 3.45B

Mean* 0.00E 2.86C 4.51A 3.92B 3.77B 2.09D

Sufaid (Year 1)

T = 0.33 W = 0.16 TW = 0.37


Water dip 0.00l 3.25bcd 6.19a 6.32a 3.76bc 6.17a 4.28A AA 250 mg/l 0.00l 4.40cde 3.89efg 4.14c-g 5.25bcd 2.24jk 3.32B AA 500 mg/l 0.00l 2.37ijk 4.34c-f 4.60b-e 2.69h-k 2.22jk 2.70C AA 750 mg/l 0.00l 4.05d-g 5.31bc 4.58b-e 3.74e-h 2.67h-k 3.39B CA 250 mg/l 0.00l 1.70k 4.20c-g 4.01d-g 2.05jk 2.08jk 2.34C CA 500 mg/l 0.00l 3.47e-i 4.29c-g 4.42cde 5.65ab 4.26c-g 3.68B CA 750 mg/l 0.00l 3.96efg 6.44a 5.31bc 3.95efg 3.07g-j 3.79B

Mean* 0.00D 3.42BC 4.64A 4.30AB 3.78AB 2.61C

Sufaid (Year 2)

T = 0.55 W = 0.39 TW = 1.09


181

Weight loss is the amount of moisture lost from fruits or vegetables with the

passage of time and is related with shelflife of produce (Lim – Byung et al., 1998). The

loss of water from fruit is due to skin evaporation (transpiration) and to some extent

respiration. In this study, the respiration rate was initially high in fruit and declined

afterwards in all treatments. The high percent of initial weight loss during the first weeks

could be attributed to stress imposed during harvest and higher respiration rates. The

decline in weight loss afterwards may imply that transpiration rate was reduced in all

treatments. The presence of ascorbic acid or citric acid, could have impaired this

hydration process.

Ayranci and Tunc (2004) reported that inclusion of AA and CA as an antioxidant

in coatings as an additive proved to be efficient only to a certain extent in reducing

weight loss in apricot. Weight of stored commodities are reported to be reduced as

storage prolongs. According to Ding et al. (1998a) low temperatures may increase the

storage period but reduction in water loss cannot be completely inhibited. Zheng and Xi,

(1999) stated that respiration rate and ethylene production in loquat can significantly be

reduced by storing the at 1 °C. Bidabe (1970) confirmed this view and reported that

weight loss in apple fruits decreased by prolonging the storage period.

Our results are in accordance with the above mentioned observation and with

Abbasi et al. (2009) who demonstrated that the reduction in weight loss is attributed to

the physiological loss in weight due to respiration, transpiration of water through peel

tissue and other biological changes occur in the fruit. Therefore, preserving at lower

182

temperature decreases respiration intensity and limits water evaporation which

eventually limits weight loss.


Firmness remained significantly high in 500 mg/l AA and 500 mg/l citric acid

(CA) while 750 mg/l AA and 250 mg/l CA were statistically non significantly during

both years and had the lowest firmness values during both years of study (Table 34.1).

During the second year control and higher concentrations of CA were non significant and

had highest firmness values. Maximum increase (1.50 and 1.46 kgf) was observed in

500 mg/l AA and 500 mg/l CA treatments during the eight week respectively (Fig. 32).

In “Sufaid” cv. s. (Table 34.2). Control had significantly lower firmness during

both years as compared to rests of the treatments. 500 mg/l AA and 250 mg/l CA were

statistically similar and had the highest firmness followed by both higher concentrations

of CA during both years. Maximum firmness was observed during sixth to eight week of

storage as compared to day one, after which it declined. Maximum firmness (1.5 kgf)

was recorded in 500 mg/l AA during eight week after which it decreased.

Results of the study show inconsistent effects of both antibrowning agents during

both years of study. Both agents had some effect on firmness. Cai et al. (2006c) reported

that firmness of loquat increased during ripening and senescence. These changes are

accompanied by flesh lignification and a decrease in juicen content (Zheng et al., 2000a;

Ding et al., 2002; Cai et al., 2006b). According to Ding et al. (2002), quality loss in

Deleted: Appendix

Deleted: Appendix

183

A

0

1

2

0 2 4 6 8 10

Firm

ness

(kgf

)

C

0

1

2

0 2 4 6 8 10

B

0

1

2

0 2 4 6 8 10


Firm

ness

(kgf

)

D

0

1

2

0 2 4 6 8 10



Fig 32: Effect of antibrowning agents on firmness in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.03, B = 0.05, C = 0.05, D = 0.05


184

Table 34.1: Effect of anti browning agents on firmness of “Surkh” loquat


Water dip 0.66m 0.96k 1.33cde 1.30def 1.33cde 1.06ijk 1.11B AA 250 mg/l 0.66m 0.60m 1.13hij 1.26d-g 1.16ghi 1.23e-h 1.01D AA 500 mg/l 0.66m 1.03jk 1.23e-h 1.26d-g 1.50a 1.43abc 1.18A AA 750 mg/l 0.66m 0.80l 1.03jk 1.26d-g 1.23e-h 1.36bcd 1.06C CA 250 mg/l 0.66m 0.80l 1.13hij 1.30def 1.13hij 1.16ghi 1.03CD CA 500 mg/l 0.66m 1.03jk 1.23e-h 1.36bcd 1.46ab 1.33cde 1.18A CA 750 mg/l 0.66m 1.06ijk 1.30def 1.43abc 1.20fgh 1.13hij 1.13B

Mean** 0.66E 0.90D 1.20C 1.31A 1.29A 1.24B

Surkh (Year1)

LSD T= 0.04 W= 0.10 TW= 0.03


Water dip 0.73kl 1.06j 1.46abc 1.40a-d 1.36b-e 1.13hij 1.19A AA 250 mg/l 0.73kl 0.63l 1.20f-j 1.30d-g 1.23e-i 1.26d-h 1.06B AA 500 mg/l 0.73kl 1.06j 1.26d-h 1.30d-g 1.53a 1.50ab 1.23A AA 750 mg/l 0.73kl 0.86k 1.1ij 1.2f-j 1.26d-h 1.36b-e 1.08B CA 250 mg/l 0.73kl 0.80k 1.20f-j 1.40a-d 1.20f-j 1.20f-j 1.08B CA 500 mg/l 0.73kl 1.06j 1.26d-h 1.40a-d 1.5a 1.40a-d 1.23A CA 750 mg/l 0.73kl 1.1ij 1.3c-f 1.46abc 1.23e-i 1.16g-j 1.17A

Mean** 0.73E 0.94D 1.26C 1.35A 1.33AB 1.29BC

Surkh (Year 2)

LSD T= 0.08 W= 0.13 TW= 0.05


185

Table 34.2: Effect of anti browning agents on firmness of “Sufaid” loquat


Water dip 0.76kl 1.03ghi 1.26bcd 1.10e-i 1.06f-i 0.80k 1.00C AA 250 mg/l 0.76kl 0.63l 1.26bcd 1.23b-e 1.26bcd 1.36ab 1.08B AA 500 mg/l 0.76kl 0.96ij 1.30bc 1.33ab 1.46a 1.36ab 1.20A AA 750 mg/l 0.76kl 0.73kl 0.80k 1.26bcd 1.16b-f 1.36ab 1.01C CA 250 mg/l 0.76kl 1.20b-f 1.20b-f 1.26bcd 1.36ab 1.23b-e 1.17A CA 500 mg/l 0.76kl 1.06f-i 0.86jk 1.36ab 1.23b-e 1.23b-e 1.08B CA 750 mg/l 0.76kl 1.0hij 1.26bcd 1.33ab 1.13d-h 1.13d-h 1.10B

Mean** 0.76E 0.94D 1.13C 1.27A 1.24AB 1.21B

Sufaid (Year 1)

LSD T= 0.04 W= 0.13 TW= 0.05


Water dip 0.83jkl 1.13fgh 1.33a-e 1.16e-h 1.13fgh 0.90ijk 1.08CD AA 250 mg/l 0.83jkl 0.66l 1.23c-g 1.26b-g 1.30b-f 1.4abc 1.11CD AA 500 mg/l 0.83jkl 1.10gh 1.33a-e 1.36a-d 1.5a 1.43ab 1.26A AA 750 mg/l 0.83jkl 0.73kl 0.8.jkl 1.26b-g 1.23c-g 1.36a-d 1.03D CA 250 mg/l 0.83jkl 1.20d-h 1.26b-g 1.30b-f 1.30b-f 1.30b-f 1.20AB CA 500 mg/l 0.83jkl 1.13fgh 0.93ij 1.43ab 1.30b-f 1.30b-f 1.15BC CA 750 mg/l 0.83jkl 1.03hi 1.30b-f 1.4abc 1.20d-h 1.2d-h 1.16BC

Mean** 0.83D 1.0C 1.17B 1.31A 1.28A 1.27A

Sufaid (Year 2)

LSD T= 0.07 W= 0.15 TW= 0.05


186

loquat fruit after harvest was mainly due to internal browning, pulp dryness and adhesion

of peel and flesh. He attributed these disorders to tissue lignification. Postharvest

firmness at low temperatures has also been reported by Zheng et al. (2000a) who

described this as a chilling injury symptom. Cai et al. (2006a) reported that increased

firmness in loquat fruit after harvest is not a specific low temperature response. Not

much is known regarding the effects of these antibrowning agents on firmness of loquat.

In this study both AA and CA showed some positive response on firmness, however it is

not clear whether it was the effect of antibrowning agents or simply due tissue

lignification as reported by the above researchers. Citric acid has been used for shelf life

extension and maintain the quality of fresh-cut Chinese Water Chestnut stored at 4 °C as

reported by Jiang et al. (2004) . Treatment with 0.1M CA markedly extended the shelf

life and reduced the eating quality loss.

Gonzalez et al. (2004) stated that firmness maintenance by antibrowning agents

may be due to the inhibition of degradation processes thus lowering of the metabolism,

which in turn may have avoided decomposition of tissue and hypothesized that loss of

texture in stored fruits was a result of enzymatic hydrolysis of cell wall components

which may justify our results.

4.6.3 Effect on Total Soluble Solids (TSS)

Citric acid 250 and 750 mg/l retained significantly higher TSS in “Surkh” cv. (Table

35.1) compared to control which had the lowest TSS (11.4 ○Brix) during both years. 500

mg/l CA had the next higher TSS (12.8○Brix and 13.0○Brix) during both years. TSS

decreased initially during first two weeks then started to increase during later weeks

Deleted: Appendix

187

however an overall decrease in TSS was observed during the ninth and tenth weeks . 250

mg/l and 500 mg/l concentrations of AA had lower TSS (12.5 ○Brix and 12.7 ○Brix)

compared to rest of the concentrations (Fig. 33).

In “Sufaid” cv., 250 mg/l AA had maximum TSS (14.1○Brix and 13.7○Brix)

during both years. 500 mg/l AA, 500 mg/l CA and 750 mg/l CA were statistically at par

during the first year but during the second year no significant difference was observed in

250 mg/l CA and 500 mg/l CA. 500 mg/l AA, 250 mg/l CA and 750 mg/l CA were at

par. Lowest TSS during both years during both years was recorded in control. TSS

remained constant during the first four weeks, with a slight increase during the sixth

week and finally started to decrease towards the end of storage during both years.

TSS content is an important parameter in judging fruit quality as consumers

consider quality factors (TSS and TA) as much as visible quality (e.g. color, size and

firmness) (Hoehn et al., 2003; Lu, 2004). The changes in TSS are directly correlated with

hydrolytic changes in the starch concentration during the post harvest period.

In this study, an increase in TSS was observed till the first six weeks followed by

a gradual decrease towards the end of storage. Increase in TSS is due to transformation of

insoluble starch into soluble solids (Martisen and Schaare, 1998; McGlone and Kawano,

1998; Vela et al., 2003) or may also be due to the accumulation of different solutes in

vacuoles of cells. Minimum TSS in control might be due to the fact that it retarded the

hydrolysis of starch into sugars and also the conversions of polysaccharides into

disaccharides and monosaccharides.

188

A

8

12

16

0 2 4 6 8 10

TSS

(Brix

)

B

8

12

16

0 2 4 6 8 10

B

8

12

16


TSS

(Brix

)

D

8

12

16



Fig. 33: Effect of antibrowning agents on total soluble solids in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.36, B = 0.43, C = 0.44, D = 0.60


189

Table 35.1: Effect of anti browning agents on total soluble solids s of “Surkh” loquat


Water dip 12.07 jk 111.7kl 11.5lm 11.4lm 11.2m 11.5n 11.4F AA 250 mg/l 12.07 jk 12.0jk 11.6lm 11.3lm 11.3lm 11.2m 11.6E AA 500 mg/l 12.07 jk 11.6lm 12.4hij 12.7fgh 13.2cde 13.1cde 12.5D AA 750 mg/l 12.07 jk 12.6ghi 13.2cde 13.1c-f 12.9efg 12.4hij 12.7C CA 250 mg/l 12.07 jk 13.0d-g 12.3hij 13.4bcd 13.7ab 13.7ab 13.0A CA 500 mg/l 12.07 jk 12.2ij 13.1cde 13.2cde 13.5bc 13.0d-g 12.8B CA 750 mg/l 12.07 jk 12.9d-g 13.3b-e 13.2cde 14.0a 12.4hij 13.0A

Mean** 12.07D 12.3C 12.5B 12.6B 12.8A 12.3C

Surkh (Year 1)

LSD T= 0.12 W= 0.13 TW= 0.36


Water dip 12.8 f-j 11.6no 11.4op 11.2opq 11.0pqr 10.6r 11.4E AA 250 mg/l 12.8 f-j 12.6h-l 12.3klm 11.6no 11.3opq 10.8qr 11.9D AA 500 mg/l 12.8 f-j 12.0mn 12.6h-l 12.8f-k 13.2c-g 13.0d-h 12.7C AA 750 mg/l 12.8 f-j 13.3c-f 13.1c-h 12.9e-i 12.7g-k 12.4j-m 12.9BC CA 250 mg/l 12.8 f-j 12.9e-i 13.0d-h 13.4b-e 13.6bc 13.8ab 13.2A CA 500 mg/l 12.8 f-j 12.2lm 13.1c-h 13.2c-g 13.5bcd 13.0d-h 13.0B CA 750 mg/l 12.8 f-j 12.9e-i 13.3c-f 13.2c-g 14.0a 12.4i-m 13.1A

Mean** 12.8A 12.5C 12.7ABC 12.6BC 12.7AB 12.3D

Surkh (Year 2)

LSD T= 0.15 W= 0.16 TW= 0.43


190

Table 35.2: Effect of anti browning agents on total soluble solids of “Sufaid” loquat


Water dip 12.8efg 12.8efg 12.8ef 11.7jk 11.7jk 10.6l 12.1D AA 250 mg/l 12.8efg 14.3b 14.4b 15.3a 14.1b 13.6c 14.1A AA 500 mg/l 12.8efg 13.2cde 13.2cde 13.2cde 12.3hi 13.4cd 13.0B AA 750 mg/l 12.8efg 12.5fgh 12.5fgh 12.3ghi 10.6l 11.4k 12.0D CA 250 mg/l 12.8efg 12.9def 12.5fgh 10.3l 13.2cde 13.2cde 12.5C CA 500 mg/l 12.8efg 12.3hi 13.2cde 13.2cde 14.2b 12.2hi 13.0B CA 750 mg/l 12.8efg 11.8ijk 11.4k 15.6a 14.3b 12.1hij 13.0B

Mean** 12.83B 12.87B 12.90B 13.12A 12.95B 12.39C

Sufaid (Year 1)

LSD T= 0.29 W= 0.16 TW= 0.44


Water dip 12.9e-k 13.0e-j 12.9e-k 11.8nop 11.5op 10.6q 12.1D AA 250 mg/l 12.9e-k 13.7a-d 14.2a 14.1ab 13.9abc 13.5b-f 13.7A AA 500 mg/l 12.9e-k 13.4c-f 13.3c-g 13.0d-j 12.3i-n 12.2k-n 12.8C AA 750 mg/l 12.9e-k 12.5h-n 12.5h-n 12.3j-n 10.6q 11.4p 12.0D CA 250 mg/l 12.9e-k 12.8f-l 12.1l-o 13.1d-i 13.3c-g 13.5a-f 12.9BC CA 500 mg/l 12.9e-k 13.0e-k 13.2c-h 13.6a-e 13.7a-d 12.4i-n 13.1B CA 750 mg/l 12.9e-k 12.0m-p 12.5i-n 13.3c-g 13.6a-e 12.6g-m 12.8C

Mean** 12.9AB 12.9AB 12.9AB 13.0A 12.7B 12.3C

Sufaid (Year 2)

LSD T= 0.24 W= 0.22 TW= 0.60


191

Numerous studies have reported that low O2 storage suppresses TSS

increase (Hoehn et al., 2003; Lu and Toivonen, 2000). A gradual increase then loss of

TSS in loquat has also been reported by (Ding et al., 1998a; Lin et al., 1999; Zheng et al.,

2000b). In this study, TSS started to increase After four weeks as shown in Fig 31. This

might be because lowered O2 suppressed TSS synthesis as explained above.

Jiang et al. (2004) reported that 0.1 M citric acid markedly reduced the loss in

total soluble solid, titratable acidity in Chinese water chestnut stored at 4 °C. Post-harvest

dipping in 150 and 300 mg/l ascorbic acid solution have also been reported to increase

TSS in ‘ber’ during storage (Siddiqui and Gupta, 1995).



No significant effect of anti browning agent on total sugars of “Surkh” cv. of

loquat was observed during both years (Table 36.1), however terms of percent losses, 750

mg/l AA had the lowest loss in total sugars (3.9%) whereas control had a loss of 8.2%

in the first year. The highest losses (19%) was recorded in 250 mg/l AA (Fig 34). During

the second year, control had the highest loss (14.5%) followed by 250 mg/l AA (12.2%).

Both these treatments differed statistically from the rest and from each other as well. In

“Sufaid” cv. of loquat no significant effect was observed during the first year however,

during the second year, higher concentrations of both AA and CA retained highest total

sugars as compared to in control. Maximum loss (11.6%) was recorded in 250 mg/l AA

in the first year. During the second year, control had maximum loss of 18.4% followed by

Deleted: Appendix

192

12.4% in 250 mg/l AA. Overall total sugars decreased during the entire ten week storage

period.


Higher concentrations of both AA and CA retained higher reducing sugars in

“Surkh” cv. during both years (Table 37.1). 750 mg/l concentration of both these agents

had the lowest losses (9.1% and 9.4%) during the first year and differed significantly

from rest of the treatments. Control and 250 mg/l AA had the highest losses (13.1% and

13.8%). 500 mg/l AA, 250 mg/l CA and 750 mg/l CA were statistically similar. In the

second year, again higher concentration (750 mg/l) of both AA and CA had the lowest

losses (10.3% and 8.9%) as compared to other treatments, while highest losses (14.1%)

were again observed in control and 250 mg/l AA. Highest loss in reducing sugars (26.8%

and 30.5%) was observed during the tenth week in 250 mg/l AA during both years.

In “Sufaid” cv. of loquat, all treatments were statistically similar in the first year.

Highest loss in reducing sugars (10.5%) was observed in control. During the second year,

750 mg/l concentration of both AA and CA had the lowest losses of (8.4% and 8.1%)

whereas highest loss of 13.8% was recorded in control. Highest loss in reducing sugars

(20.48% ) was observed during the tenth week in 250 mg/l AA in the first years while

27.3% loss was recorded in control during the second year. A gradual decrease in

reducing sugars was recorded during the ten week storage period.

Deleted: Appendix

193

A

4

6

8

10

0 2 4 6 8 10

Tota

l Sug

ars

(%)

C

4

6

8

10

0 2 4 6 8 10

B

4

6

8

10


Tota

l Sug

ars

(%)

D

4

6

8

10



Fig. 34: Effect of antibrowning agents on total sugars in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 1.17, B = 0.27, C = 0.23, D = 0.37


194

Table 36.1: Effect of anti browning agents on total sugars of “Surkh” loquat


Water dip 8.51a-d 8.58abc 8.25a-d 7.59a-f 7.22a-g 6.73efg 7.81A AA 250 mg/l 8.51a-d 8.43a-d 5.06h 7.13c-g 6.33fg 5.87gh 6.89B AA 500 mg/l 8.51a-d 8.64ab 8.10a-e 7.69a-f 7.56a-f 7.11c-g 7.93A AA 750 mg/l 8.51a-d 8.66a 8.32a-d 8.21a-d 7.92a-e 7.46a-f 8.18A CA 250 mg/l 8.51a-d 8.21a-d 7.94a-e 7.54a-f 7.27a-f 7.08d-g 7.76A CA 500 mg/l 8.51a-d 8.42a-d 8.17a-e 7.96a-e 7.47a-f 7.16c-g 7.95A CA 750 mg/l 8.51a-d 8.34a-d 8.14a-e 7.83a-e 7.37a-f 7.17b-g 7.89A

Mean** 8.51A 8.47A 7.71B 7.71B 7.30BC 6.94C

Surkh (Year 1)

LSD T= 0.72 W= 0.44 TW= 1.17


Water dip 8.67a 8.42a-d 8.19def 7.27jk 6.34m 5.60n 7.41C AA 250 mg/l 8.67a 8.40a-d 8.26cde 7.49ij 6.66l 6.18m 7.61BC AA 500 mg/l 8.67a 8.56abc 8.22de 7.90fgh 7.37jk 7.43ijk 8.02AB AA 750 mg/l 8.67a 8.64a 8.59ab 8.27cde 8.11d-g 7.55ij 8.30A CA 250 mg/l 8.67a 8.71a 8.18def 7.84gh 7.41ijk 7.16k 7.99AB CA 500 mg/l 8.67a 8.43a-d 8.31b-e 8.03efg 7.70hi 7.43ijk 8.10AB CA 750 mg/l 8.67a 8.61ab 8.23de 7.88fgh 7.43ijk 7.28jk 8.02AB Mean** 8.67A 8.54B 8.28C 7.81D 7.29E 6.95F

Surkh (Year 2)

LSD T= 0.51 W= 0.14 TW= 0.27 AA= Ascorbic acid CA= Citric acid *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)



195

Table 36.2: Effect of anti browning agents on total sugars of “Sufaid” loquat


Water dip 8.36bc 8.25bcd 7.99d-g 7.65hij 7.14lm 6.06p 7.57BC AA 250 mg/l 8.36bc 8.06de 7.78f-i 7.35kl 6.51o 6.30op 7.39C AA 500 mg/l 8.36bc 8.67a 8.27bcd 7.48jk 7.15lm 6.89n 7.80ABC AA 750 mg/l 8.36bc 8.24bcd 8.10cde 8.10cde 7.76g-j 7.54ijk 8.01A CA 250 mg/l 8.36bc 8.26bcd 7.89e-h 7.65hij 7.30kl 7.03mn 7.75ABC CA 500 mg/l 8.36bc 8.40b 8.19bcd 8.03def 7.87e-h 7.53ijk 8.06A CA 750 mg/l 8.36bc 8.24bcd 8.07de 7.91e-h 7.72g-j 7.54ijk 7.97AB Mean** 8.36A 8.30A 8.04B 7.74C 7.35D 6.98E

Sufaid (Year 1)

LSD T= 0.38 W= 0.08 TW=0.23


Water dip 8.58a 7.56i-l 7.46jkl 6.58nop 6.20p 5.66q 7.00C AA 250 mg/l 8.58a 8.47abc 7.46jkl 7.63h-k 6.62no 6.37op 7.52B AA 500 mg/l 8.58a 8.44abc 8.25a-f 7.91d-i 7.34klm 6.97mn 7.91A AA 750 mg/l 8.58a 8.27a-e 8.12b-g 8.02c-h 7.85e-j 7.66h-k 8.08A CA 250 mg/l 8.58a 8.49ab 8.17a-g 7.77g-k 7.57h-l 7.18lm 7.96A CA 500 mg/l 8.58a 8.33a-d 8.20a-g 8.12b-g 7.97d-i 7.63h-k 8.14A CA 750 mg/l 8.58a 8.31a-d 8.12b-g 7.97d-i 7.81f-j 7.66h-k 8.08A Mean** 8.58A 8.27B 7.97C 7.71D 7.34E 7.02F

Sufaid (Year 2)




196

Table 37.1: Effect of anti browning agents on reducing sugars of “Surkh” loquat


(T) 0 2 4 6 8 10 Means* Water dip 2.98a 2.77a-f 2.66-i 2.49g-m 2.40j-o 2.24no 2.59B AA 250 mg/l 2.98a 2.85ab 2.64b-j 2.48h-m 2.31k-o 2.18o 2.57B AA 500 mg/l 2.98a 2.83abc 2.64b-j 2.45h-n 2.50g-m 2.28l-o 2.61AB AA 750 mg/l 2.98a 2.78a-e 2.69b-h 2.58d-j 2.68b-h 2.54e-k 2.71A CA 250 mg/l 2.98a 2.81a-d 2.64b-j 2.55e-k 2.41i-o 2.27mno 2.61AB CA 500 mg/l 2.98a 2.87ab 2.68b-h 2.59c-j 2.52f-l 2.45h-m 2.68AB CA 750 mg/l 2.98a 2.87ab 2.74a-g 2.58d-j 2.58d-j 2.48h-m 2.70A

Mean** 2.98A 2.83B 2.67C 2.53D 2.49D 2.35E

Surkh (Year 1)

LSD T= 0.10 W= 0.07 TW= 0.20


Water dip 3.02a 2.78b-e 2.67c-h 2.47i-n 2.37lmn 2.14p 2.57C AA 250 mg/l 3.02a 2.82bc 2.63d-i 2.48i-n 2.35mno 2.10p 2.57C AA 500 mg/l 3.02a 2.84abc 2.68c-h 2.52g-m 2.40j-n 2.32no 2.63BC AA 750 mg/l 3.02a 2.91ab 2.76b-f 2.65c-i 2.56g-k 2.40j-n 2.71AB CA 250 mg/l 3.02a 2.78b-e 2.58g-j 2.50h-n 2.55g-l 2.20op 2.60C CA 500 mg/l 3.02a 2.80bcd 2.69c-g 2.62e-i 2.49i-n 2.38k-n 2.66ABC CA 750 mg/l 3.02a 2.93ab 2.82bc 2.62e-i 2.59f-i 2.53g-m 2.75A Mean** 3.02A 2.84B 2.69C 2.55D 2.47E 2.29F

Surkh (Year 2)




197

Table 37.2: Effect of anti browning agents on reducing sugars of “Sufaid” loquat


Water dip 2.85ab 2.73a-d 2.57a-g 2.42d-g 2.44d-g 2.28fg 2.55 ns AA 250 mg/l 2.85ab 2.86ab 2.72a-e 2.44d-g 2.42d-g 2.27g 2.59 ns AA 500 mg/l 2.85ab 2.81abc 2.63a-f 2.56a-g 2.54a-g 2.37efg 2.63 ns AA 750 mg/l 2.85ab 2.88a 2.68a-e 2.54a-g 2.56a-g 2.50b-g 2.67 ns CA 250 mg/l 2.85ab 2.81abc 2.70a-e 2.53a-g 2.47c-g 2.42d-g 2.63 ns CA 500 mg/l 2.85ab 2.86ab 2.71a-e 2.56a-g 2.56a-g 2.48c-g 2.67 ns CA 750 mg/l 2.85ab 2.73a-d 2.76a-d 2.63a-f 2.61a-g 2.43d-g 2.67 ns Mean** 2.85A 2.81A 2.68B 2.53C 2.51C 2.39D

Sufaid (Year 1)

LSD T= 0.19 W= 0.08 TW=0.28


Water dip 2.97a 2.78a-g 2.61f-l 2.46l-p 2.36pq 2.16r 2.56D AA 250 mg/l 2.97a 2.82a-e 2.68c-j 2.49k-p 2.40op 2.18r 2.59BCD AA 500 mg/l 2.97a 2.86abc 2.72bh 2.60f-m 2.48k-p 2.36pq 2.66ABC AA 750 mg/l 2.97a 2.88ab 2.79a-f 2.66c-k 2.63e-l 2.40nop 2.72A CA 250 mg/l 2.97a 2.73b-h 2.58g-o 2.50j-p 2.51j-p 2.22qr 2.59CD CA 500 mg/l 2.97a 2.85a-d 2.71b-i 2.58h-o 2.49j-p 2.41m-p 2.67AB CA 750 mg/l 2.97a 2.85a-d 2.82a-e 2.66d-k 2.60f-n 2.52i-p 2.73A Mean** 2.97A 2.82B 2.70C 2.56D 2.49E 2.32F

Sufaid (Year 2)

LSD T= 0.07 W= 0.06 TW= 0.16 AA= Ascorbic acid CA= Citric acid ns = Non significant *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)



Deleted: ¶¶

Deleted: ¶

198

Table 38.1: Effect of anti browning agents on non-reducing sugars of “Surkh” loquat


Water dip 5.83abc 5.88ab 5.63a-e 4.98hi 4.30j 3.99j 5.10 ns AA 250 mg/l 5.83abc 5.75a-d 5.51a-h 4.99hi 4.23j 4.15j 5.07 ns AA 500 mg/l 5.83abc 5.89ab 5.70a-d 5.48a-i 5.05ghi 5.29c-i 5.54 ns AA 750 mg/l 5.83abc 6.00a 5.91ab 5.80a-d 5.49a-i 5.27d-i 5.72 ns CA 250 mg/l 5.83abc 5.85abc 5.61a-f 5.32c-i 5.07f-i 5.06f-i 5.45 ns CA 500 mg/l 5.83abc 5.71a-d 5.71a-d 5.55a-g 5.15e-i 5.09e-i 5.51 ns CA 750 mg/l 5.83abc 5.77a-d 5.60a-g 5.41b-i 4.95i 4.95i 5.42 ns

Mean** 5.83A 5.83A 5.67A 5.36B 4.89C 4.83C

Surkh (Year 1)

LSD T= 0.58 W= 0.17 TW= 0.45


Water dip 5.80a-d 5.78a-d 5.65b-f 4.92lm 4.08o 3.56p 4.96B AA 250 mg/l 5.80a-d 5.71a-e 5.76a-e 5.12i-m 4.43n 4.19no 5.17AB AA 500 mg/l 5.80a-d 5.86abc 5.67b-f 5.50c-h 5.09j-m 5.22g-m 5.52A AA 750 mg/l 5.80a-d 5.87abc 5.96ab 5.75a-e 5.68b-f 5.27g-l 5.72A CA 250 mg/l 5.80a-d 6.07a 5.72a-e 5.47d-i 4.98klm 5.07j-m 5.52A CA 500 mg/l 5.80a-d 5.76a-e 5.76a-e 5.54c-g 5.33f-k 5.17h-m 5.56A CA 750 mg/l 5.80a-d 5.82a-d 5.55c-g 5.39e-j 4.97klm 4.88m 5.40AB Mean** 5.80A 5.84A 5.72A 5.38B 4.93C 4.76D

Surkh (Year 2)

LSD T= 0.50 W= 0.11 TW= 0.31 AA= Ascorbic acid CA= Citric acid ns = Non significant *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)



199

Table 38.2: Effect of anti browning agents on non-reducing sugars of “Sufaid” loquat


Water dip 5.77ab 5.31a-e 5.30a-e 4.52f-i 4.19hi 3.88i 4.83C AA 250 mg/l 5.77ab 5.56abc 5.03b-f 5.20a-f 4.29ghi 4.26ghi 5.02BC AA 500 mg/l 5.77ab 5.82a 5.79a 5.29a-e 4.82d-h 4.77e-h 5.38AB AA 750 mg/l 5.77ab 5.52a-d 5.56abc 5.63abc 5.30a-e 5.30a-e 5.51A CA 250 mg/l 5.77ab 5.72ab 5.50a-e 5.32a-e 5.13a-f 4.91c-g 5.39AB CA 500 mg/l 5.77ab 5.63abc 5.62abc 5.65abc 5.48a-e 5.35a-e 5.58A CA 750 mg/l 5.77ab 5.70ab 5.48a-e 5.46a-e 5.29a-e 5.37a-e 5.51A Mean** 5.77A 5.61AB 5.47BC 5.29C 4.93D 4.83D

Sufaid (Year 1)

LSD T= 0.36 W= 0.22 TW=0.60


Water dip 5.76 abc 4.92 ij 4.97 hij 4.24 kl 3.95 l 3.60 m 4.57C AA 250 mg/l 5.76 abc 5.78 ab 4.91 ij 5.27 d-i 4.34 k 4.29 kl 5.06B AA 500 mg/l 5.76 abc 5.72 abc 5.66 a-d 5.43 b-f 4.98 g-j 4.72 j 5.38A AA 750 mg/l 5.76 abc 5.53 a-e 5.47 a-f 5.49 a-e 5.34 c-h 5.37 b-h 5.49A CA 250 mg/l 5.76 abc 5.89 a 5.72 abc 5.39 b-g 5.19 e-i 5.06 f-j 5.50A CA 500 mg/l 5.76 abc 5.62 a-d 5.62 a-d 5.67 a-d 5.60 a-e 5.34 c-h 5.60A CA 750 mg/l 5.76 abc 5.60 a-e 5.44 b-f 5.44 b-f 5.34 c-h 5.27 d-i 5.47A Mean** 5.76A 5.58B 5.40C 5.27C 4.96D 4.81E

Sufaid (Year 2)




200


Results of changes in non reducing sugars of “Surkh” cv. of loquat show no

significant effect of antibrowning agents during the first year (Table 38.1). however

percent losses reveals that antibrowning agents had lower losses compared to control.

The lowest loss (1.9%) was recorded in 750 mg/l AA compared to 12.5% in control. 250

mg/l AA had the highest loss (13%) while in rest of the treatments the losses were 7%

and less. At the end of tenth week control had 31.1% less non reducing sugars as

compared to day one while 250 mg/l AA had 28.8% losses. During the second year,

almost similar results of treatments were recorded. Lowest losses (1.9%) were again

recorded in 750 mg/l AA compared to 14.1% in control. The next highest losses were

recorded in 250 mg/l AA. Losses in other treatments were less than 6.9%.

In “Sufaid” cv. of loquat (Table 40.2) 500 mg/l CA had significantly lower losses

(3.3% and 2.8%) during both years. 250 mg/l AA had the higher losses (13% and 12.2%)

following (16.3% and 20.7%) in control. Highest losses (32.8% and 37.5%) were

recorded in control at the end of tenth week.

Results of the total, reducing and non reducing sugars show that although

statistically no significant difference were observed between treatments on sugars,

however high concentration of AA and CA treated retained higher percent of sugars at

the end of storage period during both years in both cultivars of loquat. All sugars

decreased during the storage period. Flavor is considered an important quality parameter

by the consumers and effects fruit consumption (Pelayo et al., 2003). Concentration

changes in vitamin C, sugars and soluble solids during storage are essential because they

Deleted: Appendix

Deleted: Appendix

201

are the main quality parameters (Gorny et al., 2002). Sugars and organic acids contents

are key factors in determining taste attributes of fruits (Raffo et al., 2007). No work

relating to the effect of antibrowning agents on sugars retention during cold storage of

loquat has been reported.

Our results are in line with the findings of Gonzalez et al. (2005) who reported

that levels of glucose, fructose and sucrose in pine apple slices treated with different

antibrowning declined during storage. AA treatments generally maintained these sugar

levels probably by suppressing the degradation of sugars during this period. AA

appeared to slow the degradation rates of the sugars during storage by maintaining higher

levels of sugars and preventing the breakdown and oxidation of sugars. Although low

temperatures increase loquat storage periods, they may not completely control the decline

of organic acid levels or water losses during long term storage (Ding et al., 1998a). Cai et

al. (2006d) and Zheng et al. (2000a) has reported that total sugar content decreased in the

loquat fruit during storage. Similarly Ding et al. (1998b) found that sucrose declined

while fructose and glucose changed slightly during storage of loquat.

4.6.5 Effect on Titratable Acidity (TA)

Maximum TA (0.47% and 0.46%) was retained by 250 mg/l AA in “Surkh” cv. of loquat

while no significant difference was observed between control and 750 mg/l AA during

both years (Table 39.1). All citric acid treatments had significantly low TA as compared

to AA treatments. In general, TA decreased with the passage of time in all

Deleted: Appendix

202

A

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8 10

Titra

tabl

e Ac

idity

(%)

C

0.0

0.2

0.4

0.6

0.8

1.0

0 2 4 6 8 10

B

0.0

0.2

0.4

0.6

0.8

1.0


Titra

tabl

e Ac

idity

(%)

D

0.0

0.2

0.4

0.6

0.8

1.0


Water Dip

AA 250 mg/l

AA 500 mg/l

AA 750 mg/l

CA 250 mg/l

CA 500 mg/l

CA 750 mg/l

Fig. 35: Effect of antibrowning agents on titratable acidity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.04, B = 0.19, C = 0.02, D = 0.01


203

Table 39.1: Effect of anti browning agents on titratable acidity of “Surkh” loquat


Water dip 0.61 b 0.61 b 0.38 de 0.33 efg 0.29 gh 0.19 ijk 0.40B AA 250 mg/l 0.61 b 0.69 a 0.54 c 0.33 efg 0.49 c 0.16 jkl 0.47A AA 500 mg/l 0.61 b 0.36 def 0.21 ij 0.21 ij 0.20 ijk 0.13 l 0.29C AA 750 mg/l 0.61 b 0.52 c 0.34 efg 0.31 fg 0.21 ij 0.38 de 0.39B CA 250 mg/l 0.61 b 0.40 d 0.22 ij 0.21 ij 0.18 jkl 0.13 l 0.29C CA 500 mg/l 0.61 b 0.37 de 0.31 fgh 0.25 hi 0.22 ij 0.14 kl 0.32C CA 750 mg/l 0.61 b 0.29 gh 0.30 fgh 0.35 defg 0.17 jkl 0.17 jkl 0.31C

Mean** 0.61A 0.46B 0.33C 0.28D 0.25E 0.18F

Surkh (Year 1)

LSD T= 0.01 W= 0.05 TW= 0.04


Water dip 0.59 a 0.47 bc 0.36 efg 0.25 ijkl 0.23 j-m 0.14 opq 0.34BC AA 250 mg/l 0.59 a 0.59a 0.63a 0.51 b 0.47 bc 0.43 cd 0.46A AA 500 mg/l 0.59 a 0.38 def 0.23 j-m 0.21 k-n 0.18 m-p 0.12 q 0.28E AA 750 mg/l 0.59 a 0.51 i-b 0.35 efg 0.30 ghi 0.20 l-o 0.16 n-q 0.35B CA 250 mg/l 0.59 a 0.43 cd 0.26 ijk 0.21 k-n 0.17 m-q 0.13 pq 0.30E CA 500 mg/l 0.59 a 0.39 de 0.33 fgh 0.26 ijk 0.22 klm 0.14 opq 0.32CD CA 750 mg/l 0.59 a 0.34 efg 0.31 ghi 0.28 hij 0.18 m-p 0.15 opq 0.31DE

Mean** 0.59A 0.45B 0.33C 0.28D 0.23E 0.14F

Surkh (Year 2)

LSD T= 0.02 W= 0.05 TW= 0.19


204

Table 39.2 : Effect of anti browning agents on titratable acidity of “Sufaid” loquat


Water dip 0.54 a-d 0.28 ijkl 0.32 h-k 0.19 opq 0.18 opq 0.14 qr 0.27C AA 250 mg/l 0.54 a-d 0.59 ab 0.51 cd 0.43 ef 0.29 i-l 0.26 k-n 0.44AB AA 500 mg/l 0.54 a-d 0.44 e 0.50 d 0.32 h-k 0.27 klm 0.20 n-q 0.38ABC AA 750 mg/l 0.54 a-d 0.40 efg 0.33 h-k 0.23 l-o 0.23 l-o 0.24 l-o 0.33BC CA 250 mg/l 0.54 a-d 0.35 ghi 0.37 fgh 0.14 pqr 0.13 qr 0.11 r 0.27C CA 500 mg/l 0.54 a-d 0.60 a 0.52 bcd 0.57 abc 0.34 hij 0.31 h-k 0.48A CA 750 mg/l 0.54 a-d 0.21 m-p 0.21 mno 0.27 j-m 0.14 qr 0.14 pqr 0.25C

Mean** 0.54A 0.41B 0.39B 0.31C 0.22D 0.20E

Sufaid (Year 1)

LSD T= 0.13 W= 0.06 TW= 0.02


Water dip 0.54 abc 0.38 hij 0.29 mno 0.23 pq 0.19 qrs 0.13 t 0.29E AA 250 mg/l 0.54 abc 0.57 ab 0.19 cde 0.44 efg 0.30 l-o 0.24 opq 0.43B AA 500 mg/l 0.54 abc 0.43 fgh 0.47def 0.32 k-n 0.27 nop 0.20 qrs 0.37C AA 750 mg/l 0.54 abc 0.41 ghi 0.31 k-n 0.28 nop 0.20 qr 0.21 qr 0.32D CA 250 mg/l 0.54 abc 0.37 ijk 0.36 ijk 0.20 qr 0.15 rst 0.12 t 0.29E CA 500 mg/l 0.54 abc 0.59 a 0.52 bcd 0.52 bcd 0.35 i-l 0.31 k-n 0.47A CA 750 mg/l 0.54 abc 0.34 j-m 0.29 mno 0.27 nop 0.16rst 0.14 st 0.29E

Mean** 0.54A 0.44B 0.39C 0.32D 0.23E 0.19F

Sufaid (Year 2)

LSD T= 0.02 W= 0.05 TW= 0.01


205

treatments (Fig. 35). 250 mg/l AA maintained the TA level till the first four weeks after

which it started to decrease.

In “Sufaid” cv., all AA treatments and 500 mg/l CA retained significantly higher

TA, while lowest TA was recorded in control during both years. 250 mg/l AA, 500

mg/l AA and 500 mg/l CA were statistically at pat with each other in the first year

(Table 39.2). During the second year, 250 mg/l AA maintained significantly higher TA

(0.43%). TA decreased in all treatments during the ten week storage. TA in 500 mg/l

CA remained steady with little losses till the first six weeks, thereafter it started to

decrease.

Flavor is closely associated with sugar and acid ratio. Acidity is mainly

contributed by organic acids such as citric acid, malic acid, quinic acid and tartaric acid.

Malic acid is the principle organic acid in loquat and comprises about 90% while lactic

acid contributes about 10% of total organic acids present in the fruit (Ding et al., 1998b).

High acidity in fruits has an important role in retaining the flavor retention of ripened

fruit (Ulrich, 1970). In loquat, an acid concentration of 0.2 ~ 0.4% is necessary for flavor

retention (Ding et al., 2002). Organic acids in loquat have been known to decrease during

storage (Ding et al., 2002; Ding et al., 2006; Cai et al., 2006a).

These above findings of the study show that among both antibrowning agent used,

250 mg/l AA had a significant effect on retaining titratable acidity of Surkh loquat during

both years of study, similarly lower concentration of AA also had a positive effect on

Sufaid loquat during both years while 500 mg/l CA retained higher acidity during the

second year. Not much is known about the effect of antibrowning agent on changes of

Deleted: Appendix

206

organic acids of loquat, however Jiang et al., (2004) has stated that by applying 0.1 M

citric acid,shelf life of chinese water chestnut was greatly extended loss in titratable

acidity was markedly reduced.

4.6.6 Effect on SOD Activity

SOD activity of “Surkh” cv. of loquat (Table 40.1) was significantly high in

control and 250 mg/l CA (39.41 and 35.14 U/g FW) during the first year, followed by

500 mg/l CA (40.90 U/g FW ). Lowest activity (31.01 U/g FW ) was observed in 750

mg/l CA and 250 mg/l AA (28.19 U/g FW). Both, 500 mg/l AA and 750 mg/l AA were

at par. 750 mg/l AA, 500 mg/l AA and 750 mg/l CA had higher activity than control at

the end of tenth week. The activity decreased during the first two weeks, increased and

remained constant until the eight week and finally declined again in the tenth week.

During the second year, maximum activity was observed in 250 mg/l CA followed by

control (41.97 U/g FW). Both 500 mg/l AA and 500 mg/l CA were statistically similar

whereas 750 mg/l concentration of AA and CA had the lowest activity. At the end of

tenth week all treatments had higher activity than control. Overall activity decreased

during the ten week storage period (Fig. 36).

Higher concentrations of both AA and CA in “Sufaid” cv., had significantly lower

activity and were statistically similar with control (Table 40.2). Maximum activity (39.56

and 39.45 U/g FW) was recorded in 500 mg/l AA and 250 mg/l CA as compared to

control (31.75 U/g FW). During the tenth week, 250 mg/l AA, 250 mg/l CA and 500 mg/l

CA had highest activity. Overall activity fluctuated during storage, decreasing till

Deleted: Appendix

Deleted: Appendix

207

A

1

11

21

31

41

51

61

71

0 2 4 6 8 10

U/g

FW

C

1

11

21

31

41

51

61

0 2 4 6 8 10

B

1

11

21

31

41

51

61

0 2 4 6 8 10


U/g

FW

D

1

11

21

31

41

51

61

0 2 4 6 8 10


Water DipAA 250 mg/lAA 500 mg/lAA 750 mg/lCA 250 mg/lCA 500 mg/lCA 750 mg/l

Fig. 36: Effect of antibrowning agents on SOD activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 3.41, B = 3.73, C = 3.62, D = 4.13


208

Table 40.1: Effect of anti browning agents on SOD of “Surkh” loquat


Water dip 42.60def 38.07g 56.17b 40.00efg 27.50lmn 32.10hij 39.41A AA 250 mg/l 42.60def 20.03p 29.23i-m 31.50h-k 22.93op 22.87op 28.19E AA 500 mg/l 42.60def 32.57hi 30.03h-l 27.77k-n 43.67de 29.97h-l 34.43C AA 750 mg/l 42.60def 28.27j-m 29.37i-l 28.10klm 44.97cd 37.57g 35.14C CA 250 mg/l 42.60def 24.10no 48.00c 63.03a 39.37fg 26.97lmn 40.68A CA 500 mg/l 42.60def 22.47op 24.10no 44.97cd 45.93cd 40.90efg 36.83B CA 750 mg/l 42.60def 26.37l-o 33.37h 25.30mno 25.30mno 33.13hi 31.01D

Mean** 42.60A 27.41D 35.75B 37.24B 35.67B 31.93C

Surkh (Year 1)

LSD T= 1.62 W= 1.83 TW= 3.41


Water dip 47.93cd 42.10e-h 45.93def 53.73ab 35.80j-m 26.33st 41.97B AA 250 mg/l 47.93cd 23.57t 35.00k-o 26.43st 37.50ijk 29.47p-s 33.32E AA 500 mg/l 47.93cd 46.27cde 44.73def 31.17opq 32.83l-p 25.90st 38.14C AA 750 mg/l 47.93cd 43.93cd 32.93l-p 26.10st 32.97l-p 31.33n-q 35.87D CA 250 mg/l 47.93cd 36.47i-l 50.50bc 54.57a 45.10def 35.60j-n 45.03A CA 500 mg/l 47.93cd 41.73fgh 30.63pqr 25.40st 43.53d-h 39.60hij 38.14C CA 750 mg/l 47.93cd 40.27ghi 31.53m-q 36.40i-l 26.80rst 28.13qrs 35.18D

Mean** 47.93A 39.19B 38.75B 36.26C 36.36C 30.91D

Surkh (Year 2)

LSD T= 1.66 W= 1.41 TW= 3.73


209

Table 40.2: Effect of anti browning agents on SOD of “Sufaid” loquat


Water dip 45.53bc 46.20b 26.87i-l 23.20k-n 27.70hij 21.00mn 31.75D AA 250 mg/l 45.53bc 41.17cd 32.10efg 29.23ghi 35.53e 41.67cd 37.54B AA 500 mg/l 45.53bc 41.20cd 41.07d 33.50ef 41.13cd 34.90e 39.56A AA 750 mg/l 45.53bc 34.77e 23.10k-n 26.50i-l 26.20i-l 27.50hij 30.60D CA 250 mg/l 45.53bc 55.03a 44.50bcd 27.23h-k 22.77lmn 41.63cd 39.45A CA 500 mg/l 45.53bc 30.10f-i 33.87ef 31.43e-h 28.77g-j 42.73bcd 35.41C CA 750 mg/l 45.53bc 44.93bcd 24.50j-m 20.10n 22.97lmn 28.27g-j 31.05D

Mean** 45.53A 41.91B 32.29D 27.31F 29.30E 33.96C

Surkh (Year 1)

LSD T= 1.59 W= 1.37 TW=3.62


Water dip 49.37bc 45.33cd 24.20m-p 26.87j-o 26.33j-o 27.90j-n 33.33C AA 250 mg/l 49.37bc 48.70bc 37.60fg 34.90gh 37.60fg 29.33i-l 39.58A AA 500 mg/l 49.37bc 50.27bc 37.00fg 37.13fg 38.17fg 31.13hij 40.51A AA 750 mg/l 49.37bc 49.83bc 29.80bc 23.07nop 24.67l-p 28.10j-m 34.14C CA 250 mg/l 49.37bc 50.03bc 25.80k-p 43.50de 27.60j-n 28.63j-m 37.49B CA 500 mg/l 49.37bc 51.70b 33.73ghi 35.50fgh 40.10ef 26.17k-o 39.43A CA 750 mg/l 49.37bc 61.67a 25.93k-o 23.93m-p 21.07p 22.57op 34.09C

Mean** 49.37B 51.08A 30.58C 32.13C 30.79C 27.69D

Sufaid (Year 2)

LSD T= 1.73 W= 1.56 TW= 4.13


210

sixth week and increasing again in the last week. During the second year, 250 mg/l AA,

500 mg/l AA and 500 mg/l CA had highest activities and were statistically similar.

Control, 750 mg/l AA and 750 mg/l CA had significantly lower activity compared to

other treatments. SOD activity was high in 750 mg/l CA till the first two weeks after

which it started to decrease. Overall activity increased in the first two weeks and then

gradually decreased in all treatments till the end of storage.

SOD is the first line of defense from damages caused by oxygen radicals (Mittler,

2002) and its activity has been linked to physiological stresses such as low temperature,

high intensity light, water stress and oxidative stress (Bowler et al., 1992). SOD

alongwith with catalase transforms superoxide radical and hydrogen peroxide into

molecular oxygen and water, thus avoiding cellular damage (Scandalios, 1993a).

However the activity of CAT has been reported not to correspond with SOD activity

(Kawakami et al., 2000; Spychalla and Desborough (1990). In this study there was a poor

correlation between SOD and CAT. Such observations might be explained by the CAT

not working until H2O2 concentration increased beyond a certain threshold, since CAT

possesses a very low affinity for H2O2 (Kawakami et al., 2000).

SOD activity of fruits is known to decrease during storage at low temperature

(Gong et al., 2001; Kondo et al., 2005; Wang et al., 2005). Our study also shows

decreasing trend in SOD activity during the ten week storage which is in accordance with

the findings of the above mentioned researchers. However, SOD activity in pear

increased with increased concentrations of CO2 treatments during storage (Fernandez et

211

al., 2007) indicating the healthy tissues have greater capacity to produce SOD protein

because of less damaged cells (De Martino et al., 2006).

In this study, individual effect of AA and CA was mixed showing a marked

oxidative stress in loquat fruit. 250 mgl and 500 mg/l concentrations of both AA and CA

retained greater levels of SOD compared with 750 mg/l concentrations of both, showing

that oxidative stress in these concentrations might not be at dangerous levels for the

higher activities of SOD in lower concentrations (Ding et al., 2006).


Catalase activity was significantly high in 500 mg/l AA and both high

concentrations of CA while lower concentrations of AA had lower activity in “Surkh” cv.

during the first year (Table 41.1). CA 500 mg/l had high activity while control had low

activity during both years. Activity in 250 mg/l AA and all concentrations of CA

increased during the sixth week. During the second year, control and 750 mg/l AA were

statistically similar in effect. Overall activity increased till the second week and then

started to decrease (Fig 37).

Significantly high CAT in “Sufaid” cv. of loquat activity was recorded in CA

500 mg/l whereas rest of the treatments had significantly low activity during the first year

(Table 41.2). AA 250 and CA 500 mg/l had significantly high activity in the fourth week.

During the second year, Catalase activity was high in AA 500 mg/l and all CA

treatments, while control and 750 mg/l CA had the lowest activity. Storage period means

indicate that CAT activity increased in all treatments during the first two weeks and then

decreased gradually during both years.

Deleted: Appendix

Deleted: Appendix

212

A

0

1000

2000

3000

0 2 4 6 8 10

U/g

FW

C

0

1000

2000

3000

0 2 4 6 8 10

B

0

1000

2000

3000

0 2 4 6 8 10


U/g

FW

D

0

1000

2000

3000

0 2 4 6 8 10


Water Dip

AA 250 mg/l

AA 500 mg/l

AA 750 mg/l

CA 250 mg/l

CA 500 mg/l

CA 750 mg/l

Fig. 37: Effect of antibrowning agents on catalase activity in loquat cv. “Surkh” during 1st

year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.21, B = 0.05, C = 0.12, D = 0.19


213

Table 41.1: Effect of anti browning agents on catalase activity of “Surkh” loquat

Storage Period – weeks (W) Treatment (T) 0 2 4 6 8 10 Means*

Water dip 2.47k-o 3.04a-e 2.91a-g 2.33m-p 2.61h-l 2.58i-m 2.65 BC AA 250 mg/l 2.47k-o 2.76f-i 2.84fd-h 2.56i-n 2.81e-i 2.58i-m 2.67 BC AA 500 mg/l 2.47k-o 3.12ab 2.93a-g 3.08a-d 2.81e-i 2.4l-p 2.75 A AA 750 mg/l 2.47k-o 3.11abc 2.92a-g 2.71g-k 2.32nop 2.92g-k 2.63 C CA 250 mg/l 2.47k-o 3.14a 2.81e-i 2.72g-j 2.67g-k 2.19p 2.70 BC CA 500 mg/l 2.47k-o 3.08a-d 2.78f-i 2.88b-g 2.86c-h 2.59i-l 2.80 AB CA 750 mg/l 2.47k-o 2.98a-f 2.90a-g 3.13ab 2.91a-g 2.51j-o 2.74 A Mean** 2.47D 3.03A 2.87B 2.77C 2.71C 2.45D

Surkh (Year 1)

LSD T=0.12 W=0.08 TW=0.21


Water dip 2.80g-j 3.15ab 2.90efg 2.59k-o 2.69i-m 2.51nop 2.77DE AA 250 mg/l 2.80g-j 3.09bc 2.87fgh 2.60k-o 2.78g-i 2.27q 2.73E AA 500 mg/l 2.80g-j 3.16ab 2.86f-i 3.13abc 2.65j-n 2.40g-j 2.83BC AA 750 mg/l 2.80g-j 3.11abc 2.74h-k 2.78g-j 2.58l-o 2.59k-o 2.76DE CA 250 mg/l 2.80g-j 3.26a 2.93g-i 2.60k-o 2.79d-g 2.47op 2.81CD CA 500 mg/l 2.80g-j 3.16ab 2.82g-j 3.07bcd 2.88fgh 2.72h-l 2.91A CA 750 mg/l 2.80g-j 3.05b-e 2.86fgh 2.98c-f 2.92d-g 2.54m-p 2.86B Mean** 2.80CD 3.14A 2.85B 2.82BC 2.76D 2.50E

Surkh (Year 2)

LSD T=0.04 W=0.13 TW=0.05


214

Table 41.2: Effect of anti browning agents on catalase activity of “Sufaid” loquat

Storage Period – weeks (W) Treatment

(T) 0 2 4 6 8 10 Means* Water dip 2.78hi 3.08abc 2.77hi 2.25lm 2.19m 2.22lm 2.55CD AA 250 mg/l 2.78hi 3.10a-d 3.19a 2.71i 2.86gh 2.89gh 2.77B AA 500 mg/l 2.78hi 3.08a-d 2.71i 2.75hi 2.85ghi 2.22lm 2.73BC AA 750 mg/l 2.78hi 3.14ab 2.25lm 2.22lm 2.34kl 2.93efg 2.61BCD CA 250 mg/l 2.78hi 3.03b-f 2.22lm 2.22lm 2.52j 2.19m 2.49D CA 500 mg/l 2.78hi 3.12ab 3.17ab 2.96c-g 2.83ghi 2.94d-g 2.97A CA 750 mg/l 2.78hi 3.07a-e 2.41jk 2.16m 2.52j 2.90fgh 2.64BCD Mean** 2.78B 3.10A 2.60C 2.49D 2.59C 2.51D

Sufaid (Year 1)

LSD T=0.17 W=0.12 TW=0.12


Water dip 2.85ef 3.14bc 2.78efg 2.56gh 2.20jk 2.12k 2.61C AA 250 mg/l 2.85ef 3.23b 2.93cde 2.84ef 2.82ef 2.28ijk 2.82B AA 500 mg/l 2.85ef 3.17b 2.81ef 2.91def 2.88def 2.45hi 2.84AB AA 750 mg/l 2.85ef 3.14bc 2.78efg 2.31ijk 2.34ijk 2.37hij 2.63C CA 250 mg/l 2.85ef 3.54a 2.85ef 2.68fg 2.90def 2.71efg 2.92A CA 500 mg/l 2.85ef 3.19b 2.84def 2.92c-f 2.89def 2.76efg 2.91A CA 750 mg/l 2.85ef 3.11bcd 2.78efg 2.91def 2.83ef 2.71efg 2.86AB Mean** 2.85B 3.22A 2.82B 2.73C 2.69C 2.48D

Sufaid (Year 2

LSD T=0.07 W=0.19 TW=0.19


215

CAT has been found to be a major determinant of cellular resistance to the toxic

effects of hydrogen peroxide. High CAT activity is known to be preventive against

oxidant damage (Ji et al., 1988). Decreased CAT activity suggests the diminished

capacity of the cell to scavenge hydrogen peroxide (Ng et al., 2005). AA can donate

electrons in a large number of reactions making it the major ROS detoxifying compound

(Blokhina et al., 2003). CA is commonly used as an antibrowning agent, however it is

known to be an antioxidant synergist (Christopher et al., 2003). Results of the study

indicate that higher concentrations of AA and CA maintained higher CAT activity which

shows that they had a role in protection against oxidative damage as described by Ng et

al. (2005). Higher activity in CA treatments is indicative of its antioxidant synergistic

effect.

4.6.8 Effect on POD Activity

POD activity was significantly higher in both lower concentrations of AA

followed by the 250 and 500 mg/l CA during both years in “Surkh” cv (Table 42.1).

Control and 750 mg/l had significantly higher during both years. Highest activity during

the first year was recorded in control during the sixth week while 500 mg/l AA and 250

mg/l AA had highest activity during the second year in the same week. Overall activity

increased during both years, reaching its maximum in the sixth week, declined during the

next two weeks and again increased by the end of tenth week (Fig. 38).

In “Sufaid” cv. all AA concentrations had significantly higher POD activity

during the first year whereas higher concentrations had significantly lower activity during

the second year. Lowest activity during both years was recorded in 500 mg/l CA and 750

Deleted: Appendix

216

mg/l CA. During both years, 250 mg/l AA had the highest activity in the fourth week.

During the second year, 500 mg/l AA and 250 mg/l CA were statistically similar.

Overall activity increased till the fourth week, decreased during the next two weeks and

again increased by the end of tenth week during both years.

Internal quality and the rate of senescence of fruits and vegetables in storage has

been linked with antioxidants. In terms of nutritional value, the decrease in antioxidant

enzymes during storage and sometimes, the increase of POD during ripening or

senescence is of less interest than the fate of antioxidant compounds (Hodges, 2003).

Losses of these compounds during storage vary by the type of vegetable, storage

temperature and environment. Most studies of antioxidant losses have examined ascorbic

acid as being the most reactive of the antioxidants (Shewfelt, 1990). Research shows that

antioxidative enzymes play a key role in postharvest stress responses in fruits (Fernandez

et al., 2007). Antioxidant defenses against active oxygen species (AOS) depend on the

concentration and activities of antioxidative enzymes (Watkin and Rau, 2003).

POD and PPO are the main enzymes responsible for quality loss due to phenolic

degradation (Francois and Espin, 2001). POD oxidize polyphenol substances quickly in

the presence of H,O, and cause fruits or vegetables to brown together with PPO (Zhang

and Zhang, 2008). Peroxidase may indirectly enhance the browning processes by

detoxifying peroxides using antioxidant as substrates, thus catalyzing the transfer of

electrons to peroxides and oxidizing compounds that may play an active role in browning

prevention (Rojas et al., 2007). POD activity is known to increased with advancing

217

A

1

2

3

4

5

0 2 4 6 8 10

U/g

FW

C

1

2

3

4

5

0 2 4 6 8 10

B

1

2

3

4

5


U/g

FW

D

1

2

3

4

5



Fig. 38: Effect of antibrowning agents on POD activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 0.08, B = 0.08, C = 0.07, D = 0.08


218

Table 42.1: Effect of anti browning agents on POD activity of “Surkh” loquat


Water dip 2.26p 3.30ij 3.74de 4.19a 2.33p 3.36hi 3.20B AA 250 mg/l 2.26p 3.42gh 3.81cd 3.59f 3.05lm 3.74cde 3.31A AA 500 mg/l 2.26p 3.26ij 3.84c 4.06b 3.09lm 3.31i 3.31A AA 750 mg/l 2.26p 3.08lm 3.74cde 3.79cde 3.21jk 4.03b 3.35A CA 250 mg/l 2.26p 3.30ij 3.48g 3.99b 3.14kl 3.97b 3.36A CA 500 mg/l 2.26p 3.49g 3.83cd 3.33hi 2.92n 3.46g 3.22B CA 750 mg/l 2.26p 3.01m 3.76cde 3.70e 2.69o 3.41gh 3.14C

Mean** 2.26F 3.27D 3.74B 3.81A 2.92E 3.61C

Surkh (Year 1)

LSD T= 0.05 W= 1.83 TW= 0.08


Water dip 2.4 0p 2.65n 3.46fg 3.45fg 2.93kl 3.97ab 3.14BC AA 250 mg/l 2.4 0p 2.88l 3.70de 3.85c 3.18hi 3.74d 3.29A AA 500 mg/l 2.4 0p 2.96kl 3.47fg 4.00a 3.02jk 3.64e 3.25A AA 750 mg/l 2.4 0p 2.55o 3.72de 3.86c 3.12i 3.46fg 3.18B CA 250 mg/l 2.4 0p 2.79m 3.54f 4.02a 3.24h 3.10ij 3.18B CA 500 mg/l 2.4 0p 2.51fg 3.42g 3.90bc 2.65n 3.72de 3.10C CA 750 mg/l 2.4 0p 2.25q 3.45fg 3.51fg 3.44g 3.52fg 3.09C Mean** 2.4 0F 2.65E 3.54C 3.80A 3.08D 3.59B

Surkh (Year 2)


219

Table 42.2: Effect of anti browning agents on POD activity of “Sufaid” loquat


Water dip 2.30r 3.39fg 3.29hi 3.62c 2.59q 3.29hi 3.08B AA 250 mg/l 2.30r 3.32gh 3.93a 2.96m 3.04kl 3.45ef 3.17A AA 500 mg/l 2.30r 3.08k 3.58c 3.35gh 3.16j 3.49de 3.16A AA 750 mg/l 2.30r 3.39fg 3.44ef 3.57cd 2.82o 3.38fg 3.15A CA 250 mg/l 2.30r 2.98lm 3.56cd 2.88no 3.18j 3.45ef 3.06B CA 500 mg/l 2.30r 2.67p 3.28hi 3.75b 2.52q 3.45ef 3.00C CA 750 mg/l 2.30r 3.16j 3.55cd 2.73p 2.92mn 3.21ij 2.98C Mean** 2.30F 3.14D 3.52A 3.27C 2.89E 3.39B

Sufaid (Year 1)

LSD T= 0.05 W= 0.02 TW=0.07


Water dip 2.31s 2.93o 3.53ef 3.24klm 3.30i-l 3.91a 3.20B AA 250 mg/l 2.31s 3.30i-l 3.91a 3.61cd 3.26ijk 3.81p 3.35A AA 500 mg/l 2.31s 2.54q 3.35hij 3.49f 3.44fgh 3.75bc 3.15C AA 750 mg/l 2.31s 2.41r 3.33ijk 3.48fg 3.43fgh 3.52ef 3.08D CA 250 mg/l 2.31s 2.86op 3.30ijkl 3.69cd 3.09n 3.37hi 3.10CD CA 500 mg/l 2.31s 2.58q 3.38ghi 2.82p 3.24klm 3.32ijk 2.94E CA 750 mg/l 2.31s 2.94o 3.22lm 3.09n 2.34rs 3.72bc 2.94E Mean** 2.31F 2.78E 3.43B 3.34C 3.16D 3.63A

Sufaid (Year 2)


220

senescence of fruits (Tian, et al. 2004), however high O2 treatment during initial days of

storage reduced activities of PPO and POD (Ding et al. 2006).

Results of the study show that overall POD activity increased during storage. A

rise in POD activity during fruit maturation and senescence in medlar fruits has been

reported by Aydin and Kadioglu (2001), similarly El-hilali et al. (2003) reported that

POD activity in mandarin increased continuously during one month storage at 4 °C and

papaya stored at 5 °C and 15 °C for upto 30 days (Setha et al, . 2000). AA treatments

had no significant effect on POD activity of both varieties of loquat as all concentration

had high POD activity indicating that there was greater stress in these treatments.

Bruising and physiological stress may increase POD activity as a reaction to increased

oxidative stress in the fruits (Lamikanra and Watson, 2007). AA is an antioxidant and

widely used natural inhibitor of PPO for fruit products, although its effect is only

temporary because of its irreversible oxidation (Gonzalez et al. 2005) therefore AA levels

fall during storage and processing of fruits and vegetables (Veltman et al., 2000). It is

possible that AA losses its effectiveness due to the oxidation process during long term

storage. Moreover, Peroxidase has been known to detoxify peroxides using antioxidant as

substrates, thus catalyzing the transfer of electrons to peroxides and oxidizing compounds

that may play an active role in browning prevention (Rojas et al., 2007).

POD activity in fruits treated with 500 mg/l and 750 mg/l CA remained low in

both varieties compared to control. Although CA is not an antioxidant agent but acts as

an antioxidant synergist and anti-microbial agent (Christopher et al., 2003) and its

inhibiting effect is thought to be associated with the phenolase Cu-chelating power

221

(Pizzocaro et al., 1993; Jiang et al.,1999). CA is known to prevent browning of fruits

(Lopez, 2002; Severini et al., 2003; Kwak and Seong, 2005). The lower POD activity in

the higher concentrations may be due less oxidative stress as compared to the lower

concentrations and the increase in POD activity may be in response to detoxify H2O2

produced during senescence as stated by Neill et al. (2002). The quality of loquat fruits

is deteriorated by phenol-related metabolic enzymes POD and PPO (Loaiza and Saltveit,

2001). POD catalyzes the breakdown of H2O2, by releasing free radicals rather than

oxygen (Burris, 1960). POD activity may be limited by the availability of H2O2 in situ.

Hence our results are supported by the findings of the above mentioned researchers.

4.6.9 Effect on Ascorbic Acid (AA) Content

No significant difference within different concentrations of antibrowning agents

was observed on the AA content of “Surkh” cv. during the storage period (Table 43.1),

however all treatments differed significantly with control during both years. 750 mg/l AA

preserved maximum AA content with only 4 % loss while 500mg/l CA showed a 5.3%

loss during the first season. 500 mg/l AA and 750 mg/l CA both had 5.6% loss.

Maximum loss (48.1% and 46.9%) was recorded in control during the tenth week.

In “Sufaid” cv. all treatments differed significantly from control, however no

significant difference was observed within the treatments (Table 43.2) during both years.

Minimal loss of AA content (4.4%) was recorded in 750 mg/l AA followed by 250

Deleted: Appendix

Deleted: Appendix

222

A

1

2

3

4

0 2 4 6 8 10

Vit C

(m

g/10

0g F

W)

C

1

2

3

4

0 2 4 6 8 10

B

1

2

3

4


Vit C

(m

g/10

0g F

W)

D

1

2

3

4

0 2 4 6 8 10



Fig. 39: Effect of antibrowning agents on ascorbic acid content content in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for 0.32, B = 0.17, C = 0.25, D = 0.16


223

Table 43.1: Effect of anti browning agents on ascorbic acid content of “Surkh” loquat


Water dip 3.20ab 3.16ab 2.83a-d 2.43ef 2.26f 1.66g 2.59C AA 250 mg/l 3.20ab 3.06abc 2.90a-d 2.86a-d 2.73cde 2.73cde 2.91B AA 500 mg/l 3.20ab 3.23a 3.06abc 3.00a-d 2.86a-d 2.80b-e 3.02AB AA 750 mg/l 3.20ab 3.03a-d 3.10abc 3.00a-d 3.16ab 2.96a-d 3.07A CA 250 mg/l 3.20ab 3.06abc 2.96a-d 2.90a-d 2.80b-e 2.63de 2.92AB CA 500 mg/l 3.20ab 3.13abc 3.03a-d 3.10abc 2.90a-d 2.86a-d 3.03AB CA 750 mg/l 3.20ab 3.16ab 3.03a-d 3.00a-d 2.93a-d 2.80b-d 3.02AB

Mean** 3.20A 3.12A 2.99B 2.90BC 2.81C 2.63D

Sufrkh (Year 1)

LSD T= 0.14 W= 0.12 TW= 0.32


(T) 0 2 4 6 8 10 Means* Water dip 3.26a 3.16ab 3.03b-e 2.56j 2.20k 1.73l 2.66B AA 250 mg/l 3.26a 3.03b-e 3.10abc 2.86d-h 2.80f-i 2.66hij 2.95A AA 500 mg/l 3.26a 3.16ab 3.06a-d 2.96b-f 2.83e-h 2.66hij 2.99A AA 750 mg/l 3.26a 2.96b-f 2.96b-f 2.86d-h 2.76f-j 2.66hij 2.91A CA 250 mg/l 3.26a 3.13abc 2.96b-f 2.86d-h 2.73g-j 2.60ij 2.92A CA 500 mg/l 3.26a 3.13abc 3.03b-e 2.93c-g 2.80f-i 2.70hij 2.97A CA 750 mg/l 3.26a 3.13abc 3.06b-f 2.96b-h 2.86d-h 2.7hij 3.00A

Mean** 3.26A 3.10B 3.03C 2.86D 2.71E 2.53F

Surkh (Year 2)

LSD T= 0.09 W= 0.06 TW= 0.17


224

Table 43.2: Effect of anti browning agents on ascorbic acid content of “Sufaid” loquat


Water dip 3.16a 3.00a-e 2.83b-h 2.53h 2.26i 1.63j 2.57B AA 250 mg/l 3.16a 3.16a 3.13ab 3.03a-e 2.73e-h 2.80c-h 3.00A AA 500 mg/l 3.16a 3.13ab 2.96a-e 2.93a-e 2.83b-h 2.73e-h 2.96A AA 750 mg/l 3.16a 3.06a-d 3.13ab 3.03a-e 2.96a-e 2.76d-h 3.02A CA 250 mg/l 3.16a 3.16a 3.06a-d 2.83b-h 2.76d-h 2.56gh 2.92A CA 500 mg/l 3.16a 3.13ab 3.10abc 2.83b-h 2.80c-h 2.63fgh 2.94A CA 750 mg/l 3.16a 3.10abc 2.93a-f 2.96a-e 2.86a-g 2.76d-h 2.96A

Mean** 3.16A 3.11AB 3.02B 2.88C 2.74D 2.55E

Sufaid (Year 1)

LSD T= 0.17 W= 0.09 TW= 0.25


Water dip 3.23a 3.09bc 2.76i-l 2.44o 2.20p 1.70q 2.57C AA 250 mg/l 3.23a 3.20ab 3.13a-d 3.03b-f 2.80h-l 2.63l-o 3.02A AA 500 mg/l 3.23a 3.16abc 1.13a-d 2.93e-i 2.73j-m 2.56mno 2.95AB AA 750 mg/l 3.23a 3.06a-e 2.96d-h 2.86f-j 2.86f-j 2.66k-n 2.94AB CA 250 mg/l 3.23a 3.06a-e 2.93e-i 2.76i-l 2.63l-o 2.46o 2.85B CA 500 mg/l 3.23a 3.13a-d 2.93e-i 2.76i-l 2.63l-o 3.23a 2.99AB CA 750 mg/l 3.23a 3.10a-e 2.96d-h 2.93e-i 2.76i-l 2.63l-o 2.94AB

Mean** 3.23A 3.11B 2.96C 2.83D 2.65E 2.54F

Sufaid (Year 2)

LSD T= 0.12 W= 0.06 TW= 0.16


225

mg/l AA which had a loss of 5%. During the second season, AA 250 mg/l had a

minimum loss of 7.1% and was at par with AA 500mg/l, 750 mg/l and 750 mg/l CA.

AA content losses ranged from 7.1 % in 250 mg/l AA to 11.7 % in 250 mg/l CA as

compared to 20.4% in control during the second season. Overall AA content declined in

both cultivars during storage in both years of study (Fig. 39).

Ascorbic acid is an effective nutrient stability index during fruit storage

operations and has been generally seen that if it is well retained, the other nutrients are

also well retained (Fennema, 1996 ; Rueda, 2005). Use of AA and CA as antioxidants t in

post harvest treatments have been known to preserve the AA contents of fruits during

storage. Our results depict that AA content was much higher in all concentrations of both

AA and CA at the end of ten weeks storage as compared to control. These results agree

with those reported by Ayranci and Tunc (2004) who stated that AA loss rate was much

lower in stored apricots treated with AA and CA as compared to non treated fruits.

Moreover Gonzalez (2005) also reported that pineapple slices treated with AA

maintained higher levels AA content than control during storage. Similarly Jiang et al.

(2004) found that treating Chinese water chest nut with CA markedly inhibited the loss of

AA content as compared to non treated at 4 °C.

4.6.10 Effect on Radical Scavenging Activity

AA 750 mg/l had significantly higher Radical scavenging activity (RSA) in

“Surkh” cv. (Table 44.1) while 500 mg/l AA and both higher concentrations of CA had

low RSA during both years. Highest value (74.30%) was recorded in 250 mg/l AA during

the eight week in the first year while 750 mg/l AA had significantly higher

Deleted: Appendix

226

A

0

20

40

60

80

100

0 2 4 6 8 10

% In

hibi

tion

C

0

20

40

60

80

100

0 2 4 6 8 10

B

0

20

40

60

80

100

0 2 4 6 8 10


% In

hibi

tion

D

0

20

40

60

80

100

0 2 4 6 8 10



Fig. 40: Effect of antibrowning agents on radical scavenging activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 7.34, B = 6.81, C = 7.92, D = 7.14


227

Table 44.1: Effect of anti browning agents on radical scavenging activity of “Surkh” loquat


(T) 0 2 4 6 8 10 Means* Water dip 59.07cde 42.87i-l 40.10j-m 36.37l-o 43.27i-l 46.40h-k 44.68D AA 250 mg/l 59.07cde 55.53d-g 30.33o 31.40no 74.30a 50.83e-i 50.24B AA 500 mg/l 59.07cde 59.50cde 39.03k-n 59.43cde 50.97e-i 58.63cde 54.44A AA 750 mg/l 59.07cde 52.27e-h 42.27i-l 52.17e-h 64.57bc 62.77bcd 55.52A CA 250 mg/l 59.07cde 68.10ab 48.47f-j 45.87h-k 29.97o 31.73no 45.70CD CA 500 mg/l 59.07cde 50.60e-i 39.33k-n 47.23g-k 35.00l-o 46.83h-k 46.34CD CA 750 mg/l 59.07cde 59.00cde 46.70h-k 39.33k-n 56.03c-f 30.83no 48.49BC

Mean** 59.07A 55.41B 40.89E 44.54D 49.30C 46.86CD

Surkh (Year 1)

LSD T= 3.32 W= 2.77 TW= 7.34


Water dip 61.97bcd 39.70j-o 39.80j-o 37.43l-o 40.33j-o 33.43no 42.11D AA 250 mg/l 61.97bcd 48.77f-i 45.27h-l 32.47o 65.10ab 46.30g-k 49.98B AA 500 mg/l 61.97bcd 54.03d-g 33.37no 19.97p 52.90e-h 65.43ab 47.94BC AA 750 mg/l 61.97bcd 53.33efg 40.07j-o 43.50i-m 54.13d-f 70.13a 53.86A CA 250 mg/l 61.97bcd 49.13f-i 54.67c-f 34.77no 34.67no 40.87j-n 46.01C CA 500 mg/l 61.97bcd 62.67bc 46.60g-j 38.33k-o 36.17mno 54.20d-g 49.99B CA 750 mg/l 61.97bcd 59.43b-e 51.23f-i 46.47g-j 32.80no 39.23j-o 48.52BC Mean** 61.97A 52.44B 44.43C 36.13D 45.16C 49.94B

Surkh (Year 2)


228

Table 44.2: Effect of anti browning agents on radical scavenging activity of “Sufaid”

loquat


Water dip 60.77ab 39.47j-n 33.07m-o 36.17l-n 43.00h-l 42.73h-l 42.53C AA 250 mg/l 60.77ab 43.83g-l 38.43k-n 42.27h-m 41.77i-m 33.20m-o 43.38C AA 500 mg/l 60.77ab 52.73a-g 46.93f-k 56.93a-d 56.07a-f 61.97a 55.90A AA 750 mg/l 60.77ab 61.57a 50.37c-i 62.10a 60.77ab 48.83d-j 57.40A CA 250 mg/l 60.77ab 31.93no 27.07o 31.53no 49.93d-i 57.53a-d 43.13C CA 500 mg/l 60.77ab 43.07h-l 39.80j-n 56.47a-e 56.43a-e 47.43e-k 50.66B CA 750 mg/l 60.77ab 58.13a-d 38.53k-n 30.70n-o 59.50abc 51.47b-h 49.85B Mean** 60.77A 47.25CD 39.17E 45.17D 52.50B 49.02C

Sufaid (Year 1)

LSD T= 3.28 W= 2.89 TW=7.92


Water dip 62.10ab 38.90h-k 36.30ijk 33.97kl 34.23kl 37.17h-k 40.44C AA 250 mg/l 62.10ab 47.60d-g 40.43g-k 37.73h-k 40.57g-k 50.13def 46.43B AA 500 mg/l 62.10ab 47.17d-g 53.47cde 48.10d-g 54.10bcd 51.30def 52.71A AA 750 mg/l 62.10ab 38.83h-k 50.53def 47.70d-g 51.13def 64.67a 52.49A CA 250 mg/l 62.10ab 32.87kl 28.00lm 24.87m 36.07jkl 52.77def 39.44C CA 500 mg/l 62.10ab 32.90kl 48.33d-g 34.63kl 44.57f-i 54.73bcd 46.21B CA 750 mg/l 62.10ab 44.20f-j 37.63h-k 44.97e-h 54.27bcd 60.90abc 50.68A Mean** 62.10A 40.35DE 42.10D 38.85E 44.99C 53.10B

Sufaid (Year 2)


229

activity (70.13 %) in the eighth week in the second year. During both years, RSA

decreased until the sixth week followed by an increase towards the end of storage period

(Fig. 40).

Higher concentrations of AA in “Sufaid” cv. (Table 44.2) had high RSA followed by

same concentrations of CA while 250 mg/l CA had lower RSA during both years and

was statistically similar to control. Storage period means indicate that RSA decreased till

the sixth week and then increased slightly till the end of storage during both years. 750

mg/l AA had the highest RSA (62.10%) in the sixth week, while lowest RSA (27.07%

and 24.87) was recorded in 250 mg/l CA in the fourth and sixth weeks during the both

years respectively. During the second year, highest RSA (64.67%) was recorded in 750

mg/l AA in the tenth week.

Losses of antioxidants during storage vary by the type of vegetable, storage

temperature and environment. Most studies of antioxidant losses have examined ascorbic

acid as being the most reactive of the antioxidants (Shewfelt, 1990). Several other

phytochemicals are known to contribute to the total antioxidant activity of fruits and

vegetables ( Chu et al., 2000) including phenols, phenolic acids and their derivatives,

tocopherols, flavonoids, amino acids, phospholipids, peptides, phytic acid, ascorbic acid

and sterols. Phenolic antioxidants are major antioxidants that eliminate free-radicals

(Roesler et al. 2006).

Under stress conditions, the production of ROS can outrun the capacity of the

scavenging systems, resulting in oxidative damage. Under prolonged oxidative

Deleted: Appendix

230

conditions, active oxygen may cause lipid peroxidation, DNA damage, and protein

denaturation (Fridovich, 1978).

When membranes are damaged during senescence, the concentration of

antioxidant substances including ascorbic acid (AA), increases in order to counter the

effects of damage. The regeneration of AA helps to scavenge the ROS and other

harmful free radicals which might injure or kill the cells (Sonia and Chaves, 2006). AA

can liberate electrons in a vast array of enzymatic and non-enzymatic reactions making it

the major detoxifier of reactive oxygen species (ROS) in aqueous phase (Blokhina et al.,

2003). It is also the most widely used compound for fruit products, though it only has a

temporary effect because of its irreversible oxidation, hence its levels decrease during

storage of fruits (Rojas, et al. 2007). According to McCarthy and Matthews (1994),

processing of fruits and vegetables may lower ascorbic acid content of tissues. Other

findings reveal an increase in ascorbate synthesis in stress conditions, moreover changes

in the ascorbate pool is a reliable index of the stress being encountered by a cell tissues

(Stegmann et al., 1991).

In this study, higher concentration of AA had the highest RSA in both cultivars

during both years of the study followed by high concentrations of CA. Kulkarni and

Aradhya (2005) attributed low RSA in pomegranate arils during storage to a reduced

concentration of total phenolics and ascorbic acid and a surge in antioxidant activity to

an increased concentration of anthocyanin pigments whereas Padda and Picha (2008)

attributed the increase in RSA to higher total phenolic content due to exposure to low

temperature stress, which might explain the reduction in our results. In this study total

231

phenolic content showed a positive correlation (r = 0.98 and 0.66) in Surkh and (r = 0.55

and 0.87) in “Sufaid” with RSA which show that there existed a relationship between the

two parameters.

4.6.11 Effect on PPO Activity

PPO activity of “Surkh” cv. loquat remained high in control during both years

(Table 45.1), whereas higher concentrations of both AA and CA had lower activity.

Control showed high activity (77.46 and 68.21 U/g FW) during the fourth and sixth

weeks, while 250 mg/l CA showed high activity (66.85 U/g FW) in the sixth week during

the first year . During the second year, 250 mg/l AA and 500 mg/l CA were at par after

control. Lowest activity was recorded in 750 mg/l AA and 750 mg/l CA. Control showed

high activity during fourth to eight week. Overall high activity was recorded during

fourth and sixth weeks in all treatments (Fig. 41).

In “Sufaid” cv. there was a similar effect of antibrowning agents as observed in

“Surkh” cv. Control also had the highest activity in both years (Table 45.2). Higher

concentrations of both AA and CA had lower activity as compared to control. Overall no

significant change in activity was observed after the fourth week till the end of tenth

week in all treatments. During the second year, 750 mg/l AA and 750 mg/l CA had the

lowest activity (18.42 and 25.22 U/g FW). Control had the highest activity (79.84 U/g

FW) during the eight week as compared to other treatments. Overall, maximum activity

Deleted: Appendix

Deleted: Appendix

232

A

0

20

40

60

80

100

0 2 4 6 8 10

U/g

FW

C

0

20

40

60

80

100

0 2 4 6 8 10

B

1

21

41

61

81

101

121

0 2 4 6 8 10


U/g

FW

D

1

21

41

61

81

101

0 2 4 6 8 10



Fig. 41: Effect of Anti browning agents on PPO activity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 6.69, B = 6.31, C = 6.94, D = 6.55


233

Table 45.1: Effect of anti browning agents on PPO activity of “Surkh” loquat


(T) 0 2 4 6 8 10 Means* Water dip 0.61p 8.87no 77.46a 68.21b 58.11c 32.58fg 40.98A

AA 250 mg/l 0.61p 6.25op 45.44de 14.05mn 42.57e 30.15fgh 23.18C AA 500 mg/l 0.61p 1.24p 32.18fg 22.15i-l 35.01f 29.09f-i 20.05C AA 750 mg/l 0.61p 1.64op 26.42g-j 21.06j-m 13.99mn 23.25h-l 14.50D CA 250 mg/l 0.61p 1.36p 47.71de 66.85b 52.08cd 25.86g-j 32.41B CA 500 mg/l 0.61p 6.00op 18.16klm 47.85de 28.61f-j 18.16klm 19.90C

CA 750 mg/l 0.61p 1.09p 28.47f-j 45.96de 25.04g-k 16.04lmn 19.54C Mean** 0.61E 3.78D 39.40A 40.88A 36.49B 25.02C

Surkh (Year 1)

LSD T= 4.40 W= 2.52 TW= 6.69


Water dip 0.84n 7.63mn 64.72cd 97.88a 61.40de 38.89gh 45.23A AA 250 mg/l 0.84n 7.24mn 60.26de 51.56f 29.69j 36.16j 30.96BC AA 500 mg/l 0.84n 3.79mn 59.20de 41.92g 38.81gh 31.26ij 29.30C AA 750 mg/l 0.84n 3.68mn 58.76de 31.26ij 29.58j 15.1kl 23.20D CA 250 mg/l 0.84n 9.21lm 75.76b 51.65f 14.38kl 20.63k 28.75C CA 500 mg/l 0.84n 3.68mn 69.40c 58.60de 29.23j 32.76hij 32.42B CA 750 mg/l 0.84n 3.70mn 54.57ef 37.24ghi 33.17hij 18.23k 24.63D

Mean** 0.85F 5.57E 63.24A 52.87B 33.75C 27.58D

Surkh (Year 2)

LSD T= 2.90 W= 2.39 TW= 6.31


234

Table 45.2: Effect of anti browning agents on PPO activity of “Sufaid” loquat


Water dip 0.52q 8.90nop 69.73a 64.53ab 59.53bc 35.93f 39.86A AA 250 mg/l 0.52q 15.11lmn 24.97ij 66.22ab 49.20de 54.59cd 35.10A AA 500 mg/l 0.52q 6.41opq 24.71ij 26.23hi 28.07ghi 24.97ij 18.49C AA 750 mg/l 0.52q 1.59pq 17.97j-m 21.49i-l 17.21j-m 23.48ijk 13.71CD CA 250 mg/l 0.52q 5.35opq 24.56ij 28.18ghi 44.81e 62.28ab 27.62B CA 500 mg/l 0.52q 1.64pq 27.52ghi 16.44k-n 12.75mno 16.12k-n 12.50D CA 750 mg/l 0.52q 1.67pq 36.40f 33.42fgh 35.18fg 36.15f 23.89B

Mean** 0.52D 5.81C 32.27B 36.64A 35.25A 36.22A

Sufaid (Year 1)

LSD T= 5.34 W= 2.62 TW= 6.94


Water dip 0.72n 20.33jk 54.60d 66.93b 79.84a 37.53f 43.33A AA 250 mg/l 0.72n 10.56l 66.18b 49.54e 38.68f 21.98jk 31.28B AA 500 mg/l 0.72n 8.81lm 58.76cd 36.13f 32.54fgh 36.13f 28.85BC AA 750 mg/l 0.72n 3.60lmn 38.28f 24.26hij 26.40hij 17.21k 18.42D CA 250 mg/l 0.72n 8.49lm 67.65ab 64.10bc 25.15ij 31.81f-i 32.99B CA 500 mg/l 0.72n 3.06mn 63.77bc 48.81e 34.60fg 27.54g-j 29.75B CA 750 mg/l 0.72n 2.68mn 56.17d 34.81fg 35.67f 21.25jk 25.22C

Mean** 0.72F 6.05E 60.03A 47.34B 37.11C 27.02D

Sufaid (Year 2)

LSD T= 4.08 W= 2.47 TW= 6.55


235

(60.03 U/g FW) was observed during the fourth week in all treatments, after which it

started to decrease gradually.

PPO is a related to enzymatic browning and is triggered during ripening,

senescence or stress condition when the membrane is damaged, resulting in increased

PPO activity (Mayer, 1987). The activity of PPO has been known to increase during

storage of loquat at low temperatures (Cai et al., 2006a). Ascorbic acid inhibits browning

reactions by reducing the o-quinones back to phenolic substrates which are produced in

response to PPO enzymes (Robert et al., 2003) however, since AA is oxidized during the

process the protection is not permanent against discoloration as long as larger quantities

are not used (Gil et al., 1998). Citric acid also inhibits PPO due to its chelating action

(Jiang et al., 1999; Pizzocaro et al., 1993). PPO activity has been reported to increase

during storage of processed carambola stored at 4.4 °C for 6 weeks (Weller et al., 1997).

According to Lattanzio et al., (1989) both citric and ascorbic acid effectively delayed

browning reactions of the artichoke heads after 2 or 4 weeks storage. Andres et al. (2002)

has also reported that the application of AA and CA to apple cubes reduces PPO activity

by two-thirds.

Our results show highly significant effects of AA and CA on PPO activity as

compared to control. It is evident from the results that higher concentrations of both AA

and CA proved to be effective in reducing PPO activity. The possible explanation may be

that AA inhibited browning reactions by reducing the o-quinones whereas CA inhibited

PPO due to its chelating action, which is in agreement with the findings of above

236

scientists. This is also proved by by positive correlation between PPO and BI (r = 0.95,

0.67 for Surkh while r =0.70 and 0.72 for Sufaid during both years respectively.

4.6.12 Effect on Total Phenolic Content

In “Surkh” cv. (Table 46.1) lowest TP content was recorded in control, 750 mg/l

AA and 250 mg/l CA while 500 mg/l CA and 750 mg/l CA had maximum TP content

during both years. A sharp decrease in TP was observed during the first two weeks in 750

mg/l AA however TP at the end of tenth week was higher (19.20 mg.100-1) than other

two AA concentrations. During the second year, 750 mg/l had significantly higher TP

content (34.14 mg.100-1) than rest of the treatments. Overall TP content decreased during

both years in all treatments.

The treatments means of “Sufaid” cv. (Table 46.2) during the first year show no

significant difference of antibrowning agents compared to control except for 750 mg/l

AA which had a TP content of 29.51 compared to 25.81 of control. At the end of tenth

week, control had the lowest TP content (15.80 ) compared to other treatments while

highest values of 22.37 and 22.33 was maintained by 750 mg/l AA and 750 mg/l CA.

During the second year, both high concentrations of AA maintained high TP content

followed by 750 mg/l CA. Lowest TP content was recorded in control. 750 mg/l AA has

significantly higher TP content till the fourth week as compared to other treatments.

Overall TP content decreased during both years of study (Fig. 42).

Browning changes have been correlated with a decrease in total phenolics and an

increase in PPO activity (Ding et al., 1998b; Gil et al., 1998; Rocha and Morais, 2005;

Formatted

Deleted: Appendix

Deleted: Appendix

237

A

1

11

21

31

41

51

0 2 4 6 8 10

mg/

100g

FW

C

1

11

21

31

41

51

0 2 4 6 8 10

B

1

11

21

31

41

51


mg/

100g

FW

D

1

11

21

31

41

51



Fig. 42: Effect of antibrowning agents on total phenolics in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 4.86, B = 3.01, C = 3.92, D = 3.37


238

Table 46.1: Effect of anti browning agents on total phenolics of “Surkh” loquat


Water dip 36.40ab 30.90b-g 27.00f-j 23.57h-o 19.87l-q 15.23q 25.49C AA 250 mg/l 36.40ab 35.83ab 36.43ab 24.47h-n 22.53i-o 16.63pq 28.72AB AA 500 mg/l 36.40ab 35.73ab 32.77a-e 28.87c-h 22.20i-p 18.23ab 29.03AB AA 750 mg/l 36.40ab 26.40g-k 23.03i-o 25.23h-l 21.23j-p 19.20m-q 25.25C CA 250 mg/l 36.40ab 33.13a-d 27.87d-i 24.53h-n 21.00k-p 18.97n-q 26.98BC CA 500 mg/l 36.40ab 33.60abc 31.63b-g 32.50a-f 24.90h-m 22.23i-p 30.21A CA 750 mg/l 36.40ab 38.27a 34.33abc 26.47g-k 27.40e-i 22.10i-p 30.83A

Mean** 36.40A 33.41B 30.44C 26.52D 22.73E 18.94F

Surkh (Year )

LSD T= 2.42 W= 1.83 TW= 4.86


Water dip 44.83a 30.63ghi 29.63hi 25.70k-n 22.67m-p 18.17qr 28.61C AA 250 mg/l 44.83a 37.30bcd 30.73ghi 24.63l-o 20.93pq 18.03qr 29.41C AA 500 mg/l 44.83a 38.10bc 33.57efg 29.13hij 24.40l-o 23.23l-p 32.21B AA 750 mg/l 44.83a 38.77b 34.50def 32.20fgh 28.30ijk 26.23jkl 34.14A CA 250 mg/l 44.83a 29.97hi 25.83klm 25.23k-o 18.77qr 16.40r 26.84D CA 500 mg/l 44.83a 36.67b-e 29.57h-i 25.23k-o 22.10op 16.77r 29.19C CA 750 mg/l 44.83a 35.63b-e 34.90c-f 30.87ghi 25.73k-n 22.27nop 32.37B

Mean** 44.83A 35.30B 31.25C 27.57D 23.27E 20.16F

Surkh (Year 2)

LSD T= 1.58 W= 1.13 TW= 3.01


239

Table 46.2: Effect of anti browning agents on total phenolics of “Sufaid” loquat


Water dip 36.23a 34.60a 25.60c-f 23.53e-j 19.07jkl 15.80l 25.81B AA 250 mg/l 36.23a 35.33a 30.10bc 25.47c-f 20.27g-k 19.67i-l 27.84AB AA 500 mg/l 36.23a 33.53a 26.00c-f 28.60cd 25.83c-f 20.07h-l 28.38AB AA 750 mg/l 36.23a 36.83a 28.8cd 28.37cd 24.47d-h 22.37f-k 29.51A CA 250 mg/l 36.23a 34.03ab 26.53c-f 24.47d-h 22.30f-k 18.83kl 27.07AB CA 500 mg/l 36.23a 33.17ab 24.83d-g 26.93c-f 24.27d-i 20.70g-k 27.69AB CA 750 mg/l 36.23a 34.67a 27.83cde 26.00c-f 24.87d-g 22.33f-k 28.66AB

Mean** 36.23A 34.60B 27.10C 26.20C 23.01D 19.97E

Surkh (Year !)

LSD T= 3.26 W= 1.48 TW=3.92


Water dip 39.40a 32.03def 26.83hij 24.67ijk 22.00k 16.57l 26.92D AA 250 mg/l 39.40a 37.53ab 30.03e-h 23.50jk 22.47k 17.73l 28.44C AA 500 mg/l 39.40a 37.30abc 33.80cde 31.50d-g 30.63d-h 25.80ijk 33.07A AA 750 mg/l 39.40a 37.80ab 36.43abc 30.60d-h 28.33f-i 25.37ijk 32.99A CA 250 mg/l 39.40a 36.47abc 30.23e-h 27.90ghi 23.77jk 16.57l 29.06C CA 500 mg/l 39.40a 36.93abc 32.53de 27.80ghi 23.40jk 16.83l 29.48C CA 750 mg/l 39.40a 34.43bcd 30.13e-h 30.70d-h 31.20d-g 22.97jk 31.47B

Mean** 39.40A 36.07B 31.43C 28.10D 25.97E 20.26F

Sufaid (Year 2)

LSD T= 1.44 W= 1.27 TW= 3.37

A= Ascorbic acid CA= Citric acid *, ** = Means followed by a same letter are not significantly different at P=0.05(DMRT)

240

Cai et al., 2006a). AA is a water soluble antioxidant known to be important to health

(Davey et al., 2000) and is added to foods to avoid enzymatic browning (Freedman and

Francis, 1984; Soliva et al., 2002). CA inhibits PPO due to its chelating action (Jiang et

al., 1999). Both CA and AA are effective in delaying of browning reactions (Lattanzio

et al., 1989; Vincenzo et al., 1989). Severini et al. (2003) found that browning can be

prevented with CA or inclusion of antioxidants e.g. ascorbic acid, sodium or potassium

bisulphate, which avoid melanin formation or inhibit PPO.

Our results also show that both antibrowning agents (AA and CA) were effective

in maintaining the TP content as compared to control. The rate of TP decrease was

greater in control while higher concentrations of both AA and CA retained higher TP

content at the end of ten week storage (Fig. 42). In general, AA treatments retained

higher levels of TP in both varieties. Gil et al. (1998) has also reported that application

of 2% AA as an anti-browning treatment was effective in stopping decrease in TP

content during storage of ‘Fuji’ apple slices. Similarly, Lattanzio and Linsalata (1989)

reported that AA resulted in steadying the metabolism and large AA concentrations

could limit browning (Vamos-Vigyazo, 1981; Rocha and De Morais, 2005).

Free phenolics are known to be present mainly in the vacuole of cells (Xu, 2005).

Membrane damage in cell structures induced during storage allows these phenolics to

react with PPO. The lower phenolic contents recorded at the end of storage may be as a

result break up of cellular structure (Toor, 2006) leading to oxidation of TP (Cocci et

al., 2006). There existed a negative correlation between TP content and PPO, r = -0.43,

-0.58 for Surkh and r = -0.72 and -0.85 for Sufaid during both years respectively.

Formatted: Default Paragraph Font

241

4.6.13 Effect on Browning Index

Treatment means in Table 47.1 shows that lower concentrations of both ascorbic

acid (AA) and citric acid (CA) had greater BI values compared to the higher

concentrations. Maximum BI (18.72) was recorded in control while lowest BI (10.26 and

11.34) was recorded in 750 mg/l AA and 750 mg/l CA during the first year in “Surkh”

cv. of loquat. No significant difference was observed in 250 mg/l AA and 250 mg/l CA.

At the end of tenth week, control and 250 mg/l CA had 33.23% and 34.67% BI

respectively while 24.37% and 21.73% BI was recorded in 750 mg/l AA and 750 mg/l

CA. A similar trend was seen in the second year, with maximum BI (19.86 and 19.58) in

control and 250 mg/l CA while lowest value (10.84) was recorded in 750 mg/l AA. No

significant difference was observed in 250 mg/l AA, 500 mg/l CA and 750 mg/l CA.

Control and 250 mg/l CA had a BI of 41.80 and 38.60% at the end of tenth week

compared to 25.93 and 28.63 in 750 mg/l AA and 750 mg/l CA.

Maximum BI in “Sufaid” cv was also observed in control. Treatment means show

that control had the highest BI value of 20.38 and 20.35 during both years (Table 47.2).

All other treatments were statistically similar. At the end of tenth week, control had a BI

value of 38.83 and 43.57 during both years. During the second year, 250 mg/l CA had

significantly higher BI (24.06) followed by control (20.35). Higher concentrations of

both AA and CA differed significantly from control and lower concentrations of AA and

CA. In general, both “Surkh” and “Sufaid” had an increase in BI in all treatments during

both years of study (Fig. 43).

Deleted: Appendix

Deleted: Appendix

242

Dipping treatments are extensively used to protect fruits from decay. Dipping

treatments rinse the enzymes and substrates released from injured cells. The use of

synthetic chemicals for controlling browning is becoming less acceptable to consumers

(Lu and Toivonen, 2000), therefore efforts have been focused on use of natural materials

(Saper, 1993). Ascorbic acid is a well known anti-browning agent and commonly used in

fruits for a number of purposes (Soliva et al., 2002). Gonzalez et al. (2005) reported that

AA successfully inhibited PPO activity. It also reduces enzymatic browning very

efficiently as it can reduce o-quinones back to their native phenolics before they further

react and form melanins (McEvily et al., 1992). The only draw back of using AA is that

once it is completely oxidized to dehydroascorbic acid, quinones formation again begins

so relatively higher quantities of AA have to used in order to provide permanent

protection against browning (Vamos-Vigyazo, 1981).

Citric acid checks PPO activity by two ways, it brings down the pH and chelates

the copper at the active site of the enzyme (Robert et al., 2003). Copper binding looses at

the active enzyme site at pH below 4 which causes a decrease in PPO activity, permitting

the citric acid to remove the copper (Martinez and Whitaker, 1995; Limbo and

Piergiovanni, 2006). Lattanzio et al. (1989) and Vincenzo et al. (1989) reported that both

CA and AA effectively delayed browning in artichoke heads during storage.

243

A

1

11

21

31

41

51

0 2 4 6 8 10

Brow

ning

Inde

x (%

)

C

1

11

21

31

41

51

0 2 4 6 8 10

B

1

11

21

31

41

51


Brow

ning

Inde

x (%

)

D

1

11

21

31

41

51



Fig. 43: Effect of antibrowning agents on browning index in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for 2.05, B = 2.64, C = 2.30, D = 2.10


244

Table 47.1: Effect of anti browning agents on browning index of “Surkh” loquat


Water dip 0.00p 3.00no 23.17efg 25.17de 27.77c 33.23a 18.72A AA 250 mg/l 0.00p 1.26op 12.57kl 20.03hi 24.80de 31.07b 14.96B AA 500 mg/l 0.00p 0.33p 7.73m 12.07l 20.00hi 26.90cd 11.17CD AA 750 mg/l 0.00p 0.33p 4.47n 11.46l 20.90ghi 24.37ef 10.26D CA 250 mg/l 0.00p 0.66p 14.40jk 19.30i 25.13de 34.67a 15.69B CA 500 mg/l 0.00p 1.00op 14.37jk 16.50j 21.23ghi 22.40fg 12.58C CA 750 mg/l 0.00p 0.66p 12.07l 14.63jk 18.94i 21.73gh 11.34CD

Mean** 0.00F 1.03E 12.68D 17.02C 22.68B 27.77A

Surkh (Year 1)

LSD T= 1.37 W= 0.77 TW= 2.05


Water dip 0.00p 4.66o 15.70lm 26.80fg 30.17de 41.80a 19.86A AA 250 mg/l 0.00p 1.00p 13.40mn 21.83hi 24.17gh 30.30de 15.12BC AA 500 mg/l 0.00p 0.33p 11.20n 17.83kl 25.13g 29.83e 14.06C AA 750 mg/l 0.00p 0.66p 6.13o 13.33mn 18.97jk 25.93fg 10.84D CA 250 mg/l 0.00p 1.00p 11.20n 31.53de 35.13c 38.60b 19.58A CA 500 mg/l 0.00p 0.66p 13.13de 17.43kl 25.73fg 32.90cd 14.98BC CA 750 mg/l 0.00p 0.66p 16.37kl 21.10ij 26.23fg 28.63ef 15.50B

Mean** 0.00F 1.28E 12.45D 21.41C 26.50B 32.57A

Surkh (Year 2)

LSD T= 1.88 W= 1.00 TW= 2.64


245

Table 47.2: Effect of anti browning agents on browning index of “Sufaid” loquat


Water dip 0.00q 3.00q 21.40de 26.90c 32.23b 38.73a 20.38A AA 250 mg/l 0.00q 0.66q 12.07kl 13.47i-l 16.23fgh 23.53d 10.99B AA 500 mg/l 0.00q 0.66q 8.06no 12.87jkl 15.83f-i 21.90de 9.88BC AA 750 mg/l 0.00q 0.33q 6.73no 11.20lm 14.43g-k 18.04f 8.45CD CA 250 mg/l 0.00q 0.00q 5.53o 12.07kl 16.93fg 22.53de 9.51BCD CA 500 mg/l 0.00q 0.33q 7.00no 11.93kl 18.13f 20.97e 9.72BCD CA 750 mg/l 0.00q 0.00q 6.86no 9.12mn 14.00h-k 14.73g-j 7.45D

Mean** 0.00E 0.71E 9.66D 13.94C 18.26B 22.92A

Sufaid (Year 1)

LSD T= 2.24 W= 0.87 TW= 2.30


Water dip 0.00o 4.16n 18.20i 25.83efg 30.33d 43.57a 20.35B AA 250 mg/l 0.00o 3.33n 15.67jk 20.93h 26.43ef 29.90d 16.04C AA 500 mg/l 0.00o 0.60o 12.37l 14.43kl 18.40i 23.83g 11.61D AA 750 mg/l 0.00o 0.66o 9.33m 13.80kl 17.77ij 24.63fg 11.03D CA 250 mg/l 0.00o 0.33o 27.23e 34.37c 39.50b 42.90a 24.06A CA 500 mg/l 0.00o 0.00o 8.73m 15.03k 20.02hi 27.67e 11.91D CA 750 mg/l 0.00o 0.33o 7.70m 9.70m 18.43i 24.73fg 10.15D

Mean** 0.00F 1.34E 14.18D 19.16C 24.41B 31.03A

Sufaid (Year 2)

LSD T= 1.83 W= 0.82 TW= 2.10


246

Citric acid can prevent browning of sliced apple and extend its shelf life (Santerre

et al., 1988). Our results show that higher concentrations of both AA and CA

significantly reduced BI of loquat fruit during storage compared to control which had

higher BI. This may be due to the fact that both higher concnentrations inhibited the the

activity of PPO. These results are in accordance with the findings of the above scientists.

4.6.14 Effect on Relative Electrical Conductivity

The highest relative electrical conductivity (REC) (51.26% and 50.14%) during

both years was recorded in control while higher concentrations of AA had significantly

lower REC values compared to CA concentrations during both years in “Surkh” cultivar

(Table 48.1). The higher concentrations of CA were more effective than the lower

concentration throughout both years. Overall REC increased during the ten week storage

period. In control, REC started to increase during the fourth week onward reaching a

maximum of 67.30% in the tenth week, while 250 mg/l CA had the next higher value of

61.10% at the end of tenth week. During the second year, REC in control was raised

from 57.43% in the sixth week to 71.47% at the end of tenth week while it was above

60% in all CA treatments in the tenth week.

Relative electrical conductivity of “Sufaid” cultivar in Table 48.2 reveals that

maximum REC was recorded in control during both years. Higher concentrations of AA

were statistically superior than the same concentrations of CA. Storage period means

show that REC increased with the progress of storage period (Fig. 44). Lowest REC was

recorded in 750 mg/l AA during both the years. In both years, REC in control increased

in the sixth week and remained almost constant till the end of tenth week.

Deleted: Appendix

Deleted: Appendix

247

Cellular membranes are made up proteins related with a lipid bilayer matrix (Voet

and Voet, 1990) and play an important role in the maintaining compartments of cells.

Stresses induced by water losses, fluctuating temperatures, radiation, and harmful

chemicals can disturb proper functioning of cell membrane systems by changing the

membranes physiochemical properties. The usual signs of damage by malfunction of

membrane systems include water-soaked appearance, turgor loss, electrolytes leakage,

and tissues discoloration (Fan and Sokorai, 2005).

Electrolyte leakage normally serves as an index damage done to plant cell

membranes (Xuetong and Kimberly, 2005). Reactive oxygen species (ROS), such as O2-

, OH- and H2O2 may cause leakage of cell membrane (Cai et al., 2006a; Tian et al., 2007)

by attacking the unsaturated bonds in membrane phospholipids which are the prime

targets of free radical reactions leading to lipid peroxidation (Opara and Rockway, 2006).

As a consequence, the structure and fluidity of the membrane are disrupted which results

in loss of natural functioning of the cells (Ng et al., 2005). Electrolytes are confined

inside plant cell membranes and are very susceptible to environmental stresses.

Unstressed and healthy plant cells hold electrolytes within the membrane. During stress

the electrolytes escape from the cells into surrounding tissues. High conductivity

indicates leakage of intracellular ions which depict damage to membranes

(Ade-Omowaye et al., 2003). In plant cell membranes, these changes are seen as

increased permeability and loss of integrity (Campos et al., 2003). It can be deduced that

during storage the plasma membrane of the cell becomes unstable and eventually causes

a leakage of electrolytes (Feng et al., 2005).


248

A

0

20

40

60

80

100

0 2 4 6 8 10

Rel

ativ

e El

ectri

cal C

ondu

ctiv

ity (%

)

C

0

20

40

60

80

100

0 2 4 6 8 10

B

0

20

40

60

80

100


Rel

ativ

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ectri

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ondu

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)

D

0

20

40

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80

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Fig. 44: Effect of antibrowning agents on relative electrical conductivity in loquat cv. “Surkh” during 1st year (A), 2nd year (B), and cv. “Sufaid” during 1st year (C), 2nd year (D). Vertical bars represent SE of means. LSD for A = 2.88, B = 6.10, C = 5.18, D = 6.68


249

Table 48.1: Effect of anti browning agents on relative electrical conductivity of “Surkh” loquat


(T) 0 2 4 6 8 10 Means* Water dip 29.83p 38.80lmn 50.33e-h 55.63de 65.63ab 67.30a 51.26A AA 250 mg/l 29.83p 33.17op 48.03f-i 45.33h-k 39.17lmn 43.93i-l 39.91D AA 500 mg/l 29.83p 37.43mno 47.83f-i 48.23f-i 43.17i-m 42.57i-m 41.51D AA 750 mg/l 29.83p 35.07nop 39.97k-n 32.47op 31.80op 35.80no 34.16E CA 250 mg/l 29.83p 45.17h-k 51.52d-g 52.00d-g 55.20de 61.10bc 49.14AB CA 500 mg/l 29.83p 40.20k-n 46.53g-j 51.33d-g 52.87def 57.07cd 46.31BC CA 750 mg/l 29.83p 35.20nop 41.53j-m 47.37f-i 53.20def 62.30ab 44.91C

Mean** 29.83E 37.86D 46.54C 47.48BC 48.72B 52.87A

Surkh (Year 1)

LSD T= 3.32 W= 1.87 TW= 2.88


Water dip 25.70p 39.33k-n 46.83g-j 57.43b-e 60.10bcd 71.47a 50.14A AA 250 mg/l 25.70p 37.63lmn 46.03h-k 49.43f-i 41.67j-m 45.27ijk 40.96D AA 500 mg/l 25.70p 32.50no 48.03g-j 52.33e-i 42.17jkl 46.03h-k 41.13D AA 750 mg/l 25.70p 27.87op 41.43j-m 36.33lmn 33.10no 33.63no 33.10E CA 250 mg/l 25.70p 34.80mn 48.17f-j 53.10e-h 55.20c-f 61.23bc 46.37B CA 500 mg/l 25.70p 35.50lmn 45.97h-k 52.00e-i 57.30b-e 63.57b 46.67B CA 750 mg/l 25.70p 33.20no 37.33lmn 51.33e-i 53.53d-g 60.50bc 43.60C Mean** 25.70E 34.40D 44.83C 50.28B 49.01B 54.53A

Surkh (Year 2)


250

Table 48.2: Effect of anti browning agents on relative electrical conductivity of “Sufaid” loquat


(T) 0 2 4 6 8 10 Means* Water dip 30.30p 38.77j-n 46.73d-h 68.33a 65.33a 67.63a 52.86A AA 250 mg/l 30.30p 38.60k-n 43.10g-k 39.47i-m 35.83l-p 45.70d-h 38.83DE AA 500 mg/l 30.30p 33.53m-p 44.93e-j 42.43h-k 42.30h-k 55.53b 41.51C AA 750 mg/l 30.30p 41.73h-l 49.07c-g 39.20p 33.30nop 34.33m-p 37.99E CA 250 mg/l 30.30p 37.87k-o 49.30c-f 43.87f-k 67.17a 67.17a 49.33B CA 500 mg/l 30.30p 34.50m-p 44.03f-k 41.97h-k 50.37b-e 52.87bc 42.3C CA 750 mg/l 30.30p 32.33op 41.20h-l 45.30d-i 47.00c-h 51.10bcd 41.21CD Mean** 30.30E 36.76D 45.48C 45.80C 48.76B 53.52A

Sufaid (Year1)

LSD T= 2.40 W= 1.96 TW=5.18


Water dip 26.63qr 41.93h-l 41.37h-l 57.77bcd 61.07bc 71.73a 50.08A AA 250 mg/l 26.63qr 32.70m-q 43.60g-k 26.63qr 38.77j-n 41.07h-l 37.18D AA 500 mg/l 26.63qr 24.20r 36.47k-o 40.73h-l 43.53g-k 48.37e-h 36.66D AA 750 mg/l 26.63qr 27.80pqr 31.97n-r 39.20j-n 32.17m-q 32.43m-q 31.70E CA 250 mg/l 26.63qr 28.20pqr 55.27cde 48.00e-i 55.27cde 64.00b 43.87B CA 500 mg/l 26.63qr 31.87n-r 35.07l-p 45.33f-j 50.50d-g 56.90bcd 41.05C CA 750 mg/l 26.63qr 30.43o-r 32.87m-q 39.63j-n 48.67e-h 52.33def 38.43CD Mean** 26.63F 31.02E 37.49D 44.43C 47.14B 52.40A

Sufaid (Year 2)


251

The results of the study reveal highly significant effect of AA on REC of both

loquat cultivars during storage. The REC of the fruit tissue increased continuously

storage, showing a gradual disruption of cell membranes and increasing senescence of

the tissue.

Citric acid is an antioxidant synergist (Christopher et al., 2003) whereas ascorbic

acid is an antioxidant and can directly or indirectly scavenging harmful free radicals.

Because of its irreversible oxidation it effect is only temporary (Rojas, 2007). The

ability of AA to liberate electrons in enzymatic and non-enzymatic reactions makes it the

most successful reactive oxygen species (ROS) detoxifying compound (Blokhina et al.,

2003). The concentration of antioxidant substances including AA in cells may increase

during tissue senescence to fight the generation of ROS and other free radicals causing

cell injury (Sonia and Chaves, 2006). From the above results it is clear that the

antioxidant properties of AA helped to scavenge the harmful free radicals which in turn

reduced electrolyte leakage by keeping the membranes intact as compared to CA

treatment. This result is also supported by the highly significant negative correlation

between REC and RSA (p < 0.05), r = -0.88 and -0.86 for Surkh and r =-0.80 and -

0.75 for Sufaid during both years respectively.

4.8 CONCLUSION

Higher concentrations of Ascorbic acid held fruit quality much better then

citric acid for up to 4-5 weeks

Higher concentrations of both Ascorbic acid and Citric acid reduced

browning significantly

252

Ascorbic acid content of both cultivars was not effected by antibrowning

agents during both year, however all treatments differed significantly from

control

Reducing, non reducing and total sugars were not effected by anti

browning agents in both cultivars

253

GENERAL DISCUSSION

Fruits and vegetables are an essential part of human diet because they are a

source of essential vitamins and antioxidants which help to neutralize harmful free

radicals, hazardous to human health. Studies on loquat postharvest treatments have

shown several physiological changes occurring during postharvest storage among which

flesh browning is a major problem which adversely affects its quality and is a symptom

of fruit decay. Loquat is a popular fruit but due to its perishable nature it has a short shelf

life, therefore search is being done to find suitable and cost effective postharvest

treatments to maintain its freshness and increase its shelf-life. This study was designed to

find out potential of easily available and low cost polyethylene films and naturally

occurring GRAS chemicals to extend loquat shelf life and to evaluated changes in

antioxidants along with other physiological changes during cold storage as influenced by

these treatments.

The results of the first study reveal consistent changes in all quality parameters

as the fruit progresses towards senescence after harvest. The major changes include an

increased firmness, decline in acidity and an increment in TSS followed by a gradual. All

these quality parameters mainly have a direct effect on flavor which is very crucial from

the consumer point of view (Pelayo et al., 2003). Low temperature may increase the

storage periods to some extent but decrease in quality and weight losses can not be

completely controlled (Ding et al., 1998b). In this study, TSS of control increased in

both cultivars while in PE treatments, it gradually decreased. Decreased TSS in PE

254

treatments may be attributed to retarded respiration leading to lesser conversions of

polysaccharides into disaccharides and monosaccharides.

Weight loss was high in control while non perforated packages retained greater

weight than perforated packages in both cultivars. Polyethylene packages not only

reduced weight losses but also maintained firmness and titratable acidity, whereas fruit

without any PE package had greater losses of these parameters. Ding et al. (2002)

reported that non perforated polyethylene (PE) bags reduced weight loss more effectively

as compared to perforated PE bags in loquat.

Titratable acidity is directly related to the concentration of organic acids present

in the fruits. Studies have shown that PE packages minimizes reduction in organic acids

(Ding et al., 1997). In this study, HDPE retained maximum TA in both cultivars, during

both years. Control and perforated PE packages had greater loss of acidity which could

be due to rapid consumption of malic acid by the microorganisms as a carbon source or

due to break up of acids into sugars during respiration Ball (1997). HDPE also

maintained highest sugars whereas there was greater losses in control in both cultivars

during both years.

Non perforated packages retained higher SOD activity as compared to control and

perforated treatments, showing that oxidative stress in these treatments was less. CAT

activity was higher in the first and second weeks of storage probably due to the

accumulation of respiratory H2O2 because of high respiration and then decreased during

the later weeks showing lesser capacity of the cell to scavenge H2O2 (Ng et al., 2005).

The results also indicate that HDPE maintained higher CAT activity which shows that it

255

had a role in protection against oxidative damage as described by Ng et al. (2005). No

correlation was found between SOD and CAT activities, showing that CAT was not

activated until H2O2 concentration increased beyond a certain limit (Kawakami et al.,

2000). POD activity fluctuated in all treatments generally increased towards the end of

storage which shows a need for H2O2 removal triggered during the gradual fruit

deterioration (Neill et al., 2002).

PPO activity was high in control and HDPE treatments of both cultivars while

both low density PE packages had low activity which indicates that substrate inhibition

of PPO as reported by Kader (2002b). BI was also high in control and HDPE followed

by both perforated packages. LDPE had the lowest BI in both years. PPO is closely

related with browning index and is proved by the strong positive correlation r = 0.85 and

0.96 for Surkh while r =0.75 and 0.74 for Sufaid during the first and second years

respectively.

Polyethylene packages effectively maintained TP content of both varieties

compared to control. Overall TP content decreased in the last weeks of storage possibly

as a results of decomposing cell structures as reported by Toor and Savage (2006). Fruit

stored in controlled atmosphere conditions have been found to have a gradual decrease in

total phenol content (Tian et al., 2005).

Polyethylene Packages did not affect AA content within different PE treatments,

however control had lower AA content than all PE treatments at the end of tenth week,

possible due to greater utilization of organic acids during respiration or their conversion

to sugars (Kader, 2002a). Ascorbic acid oxidizes rapidly which may explain the higher

256

loss in control treatment due to higher concentrations of O2 compared to polyethylene

packages.

Radical scavenging activity (RSA) was significantly higher in non perforated PE

packages than control and perforated treatments. Piga et al. (2002) also reported that

less permeable film resulted in better retention of antioxidant activity. Fruits have high

RSA due to large amounts of polyphenolics and vitamins including ascorbic acid , which

act as radical scavengers. During tissue senescence, the cells have higher concentrations

of antioxidants including ascorbic acid to compensate the damage causing a rise in RSA.

This is also proved by the strong positive correlation between RSA and AA (r = 0.97,

0.76 for Surkh while r =0.89 and 0.90 for Sufaid during both years respectively).

Control had high EC in both cultivars. All Packages were similar in effect during

the first year, however during the second year, LDPE had a significant difference from

rest of the packages. In “Sufaid” cultivar both perforated and non perforated packages

were statistically same during both years.

Internal browning is the major factor which adversely effects the quality of loquat

after harvest (Ding et al., 2002a) due to oxidation of phenolic compounds (Ding et al.,

2006). Internal flesh browning is the main cause of fruit decay in loquat fruit which

results in complete rotting. Our results reveal significantly lower BI in perforated and

low density PE, whereas HDPE had significantly higher BI. This shows that may be

LDPE and perforated packages had a greater gas permeability which resulted in lower

BI, which is also supported by Ding et al. (2002a).

257

Calcium has been studied extensively as an essential element and its role in

maintaining postharvest quality of fruits. It plays a vital role in membrane stability

(Kirkby and Pilbeam, 1984) by contributing to the linkages between pectic substances

within the cell-wall (Demarty et al., 1984) and slows down senescence as well as fruit

ripening (Ferguson, 1984).

In order to expand the fresh produce market, exploration of possible methods to

extend storage-life perishable commodities is required. The use of additional Ca2+

application to commodities has been viewed as the potential non-fungicidal, senescence

delaying treatment (Esmel, 2005). Postharvest applications allow Ca2+ solutions to have

direct contact with the surface of the fruit Conway et al. (1992).

Results of the second study indicate that maximum weight losses in both cultivars

occurred in control while lowest loss was recorded in 3% CaCl2 during both years,

showing that calcium might have delayed senescence and lowered both respiration and

transpiration.

Two percent and 3% CaCl2 had maximum firmness, which increased in both

cultivars during storage. Increase in firmness of loquat during storage can be attributed

to tissue lignification as reported by Cai et al. (2006d). Cross linking of pectic polymers

is facilitated by the deposition of calcium in the cell walls which strengthens the cell

walls and cell cohesion (White and Broadly, 2003).

Two percent and 3% CaCl2 retained TSS probably by forming a thin layer on the

fruit surface resulting in delaying degradation and reducing evaporation from the fruits.

258

3% CaCl2 had the highest sugars in both cultivars. Sugars and acids contents are major

constituents of the taste attributes of fruits. Sucrose is the carbon source imported in the

cells and used during respiration (Mir and Beaudry, 2002). Overall all sugars decreased

which has also been reported by Ding et al., 1998b; Amaros et al., 2008; Cai et al.,

2006d). This decrease may be due to their consumption as respiratory substrates (Mir

and Beaudry, 2002).

Titratable acidity in “Surkh” cv. of loquat was not siginificantly affected by

CaCl2 treatments, however in “Sufaid” cultivar, 2% CaCl2 had higher TA during both

years which has also been reported by Manganaris et al. (2005).

SOD activity was high in control and 2% CaCl2 during both years, while 1%

CaCl2 had the lowest activity. Overall activity decreased during storage. In Sufaid

cultivar, 2% and 3% CaCl2 had high activity. SOD and H2O2 is known to disrupt Ca2+ -

ATPase activity causing a prolonged release of calcium and elevation of cytoplasmic

calcium content (Paliyath and Droillard, 1992) promoting decompartmentation. One

percent and 2% CaCl2 had higher CAT activity. In “Sufaid” cv. 2% CaCl2 and 3%

CaCl2 retained maximum activity while control had the lowest activity. Wang (1995)

reported that catalase activity decreases at low temperatures. In this study calcium treated

fruits had higher activity compared to control perhaps because calcium maintained

respiration activities in treated fruits. A poor correlation existed between SOD and CAT

showing that the degree of oxidative stress varied in the treatments.

POD activity was high in control and 1% CaCl2 in both cultivars. Lowest activity

was recorded in 2% CaCl2. POD catalyzes the decomposition of H2O2 (Burris, 1960)

Deleted: 89

Deleted: exisited

259

while physiological stress and injuries can stimulate POD activity due to oxidative stress

in the fruits (Lamikanra and Watson, 2001). The lower activity in control and 1% CaCl2

may be due less oxidative stress with respect to other treatments whereas higher POD

activity may be in response to detoxify H2O2 produced during senescence as stated by

Neill et al. (2002).

All CaCl2 treatments maintained AA content compared to control in both

cultivars. Radical scavenging activity was high in higher concentrations of CaCl2

compared to control. Antioxidant capability of horticultural commodities are influenced

by several phytochemicals including ascorbic acid, which make up the total antioxidant

activity (Chu et al., 2000). In this study AA showed a positive correlation with RSA

(r = 0.99 and 0.99) in Surkh and (r = 0.95 and 0.57) in Sufaid, proving a relationship

between the two parameters perhaps because during tissue senescence the concentration

of antioxidant substances including AA is increased (Sonia and Chaves, 2006).

Control had high PPO activity in both cultivars while 2% and 3% CaCl2 had low

activity, similarly control also had maximum BI in both cultivars, lowest BI was

observed in 3% CaCl2. Mayer (1991) reported that PPO is activated during ripening,

stress or during senescence when membranes are afflicted and CaCl2 applied

exogenously stabilized plant cell walls protecting them from enzymes effecting the cell

walls (White and Broadley, 2003). In this study high concentrations (3%) significantly

reduced PPO activity perhaps because calcium stabilized the membranes against free

radicals as found by Klien and Lurie (1994). When analyzing the possible relationship

between BI and PPO activity, a strong positive correlation was observed (r = 0.79,

Deleted: et al.

260

0.85 for Surkh while r =0.94 and 0.72 for Sufaid during the first and second years

respectively.

3% CaCl2 retained maximum TP content in both cultivars during both years

while control had low TP content. Soluble phenolic compounds accumulate in the

vacuoles of fruit cells (Macheix et al., 1990). Damage of cell membranes lead to

senescence related peroxidation of membrane lipids and finally to tissue browning

(Thompson et al., 1987). The changes occurring as a result of browning include decline

in total phenolics and rise in PPO activity (Cai et al., 2006a). Higher TP content in CaCl2

treated fruits may therefore be due to fact that CaCl2 maintained cell structures,

controlling deterioration of membranes resulting in separation of phenolic substrates

from PPO.

Highest REC in both cultivars during both years was recorded in control. Both

higher concentrations of CaCl2 had lower REC values. Cell membrane disruption leads

to senescence (Itzhaki et al., 1990). Supplemental calcium may decrease the rate of

senescence (Nan, 2007) resulting in decreased electrolyte leakage from cells (Mortazavi

et al., 2007). In this study, 3% CaCl2 had the lowest decrease in REC in both cultivars

showing that there was less disruption in the plasma lemma membranes as reported by

Meng et al. (2009).

Result of the third study reveal that weight loss and firmness were not influenced

by antibrowning agents as seen by the fluctuating results. Ayranci and Tunc (2004) has

also reported that addition of AA and CA as an antioxidant in coatings as an additive

proved to be efficient only to a certain extent in reducing weight loss in apricot.

261

Higher TSS was retained in CA treatments in “Surkh” cv., while lowest TSS

during both years was recorded in control. In “Sufaid” cv., 250 mg/l AA had maximum

TSS during both years. 500 mg/l AA, 500 mg/l CA and 750 mg/l CA were statistically at

par. Jiang et al. (2004) reported that citric acid reduced the loss in TSS and TA in

Chinese water chestnut stored at 4 °C, similarly dipping in 150 and 300 mg/l ascorbic

acid solution after harvest, increased TSS in ‘ber’ during storage (Siddiqui and Gupta,

1995).

Results of the total, reducing and non reducing sugars show that although

statistically no significant difference were found between treatments, however high

concentration of AA and CA retained higher percent of sugars in both cultivars at the

end of tenth week. AA treatments generally maintained higher sugar levels of reducing

and non reducing sugars in pine apple slices during storage at 10 °C; probably by

suppressing degradation of sugars. AA appeared to maintain sugars by preventing the

breakdown and oxidation.

In this study, 250 mgl and 500 mg/l concentrations of both AA and CA had

higher SOD activity compared to 750 mg/l concentrations of both, showing that the level

of oxidation stress in these concentrations is not as much as for the higher activities of

SOD in lower concentrations (Ding et al., 2006).

Catalase activity was significantly high in 500 mg/l AA and both high

concentrations of CA in both cultivars while control had low activity during both years.

High CAT activity show greater ability against oxidative damage (Ji et al., 1988). AA is

a major ROS detoxifying compound (Blokhina et al., 2003) while CA is commonly used

262

as an antibrowning agent and antioxidant synergist (Christopher et al., 2003). Results

indicate that higher concentrations of AA and CA maintained higher CAT activity which

shows that they had a role in protection against oxidative damage as described by Ng et

al. (2005). Higher activity in CA treatments is indicative of its antioxidant synergistic

effect. SOD and CAT transform dangerous radicals into oxygen and water, avoiding

damage to cells (Scandalios, 1993a), however there are reports of CAT being working

independently (Kawakami et al., 2000; Spychalla and Desborough (1990). In present

study no strong correlation existed between SOD and CAT, proving that CAT not

working until H2O2 concentration increased beyond a certain limit (Kawakami et al.,

2000).

POD activity was significantly higher in both lower concentrations of AA in

“Surkh” cv while control and 750 mg/l had high activity. In “Sufaid” cv. all AA

concentrations had significantly higher POD activity showing greater stress in these

treatments. AA is a natural inhibitor of PPO but due to its irreversible oxidation

(Gonzalez et al. 2005) its levels decrease during storage (Veltman et al., 2000). It is

possible that AA looses its effectiveness due to the oxidation process during long term

storage. Citric acid is known to prevent browning of fruits (Severini et al., 2003;

Kwak and Seong, 2005). The lower POD activity in the higher concentrations of CA

may be due less oxidative stress as compared to the lower concentrations as stated by

Neill et al. (2002).

AA content was not effected by antibrowning agents during the storage, however

all treatments differed significantly from control during both years. 750 mg/l AA

263

preserved maximum AA. Our results depict that AA content was much higher in all

concentrations of both AA and CA at the end of ten weeks storage as compared to

control. Ayranci and Tunc (2004) has also reported that AA loss rate was lower in

stored apricots treated with AA and CA as compared to non treated fruits.

In this study, higher concentration of AA had the highest RSA in both cultivars

during both years of the study followed by high concentrations of CA. Several

phytochemicals including AA makeup the total antioxidant activity of horticultural crops

(Chu et al., 2000). Phenolic antioxidants mainly destroy free-radicals (Roesler et al.

2006). Kulkarni and Aradhya (2005) attributed low RSA to a reduced concentration of

total phenolics and ascorbic acid and a surge in antioxidant activity to an increased

concentration of anthocyanin pigments whereas Padda and Picha (2008) attributed the

increase in RSA to higher total phenolic content due to exposure to low temperature

stress. In this study total phenolic content showed a positive correlation (r = 0.98 and

0.66) in Surkh and (r = 0.55 and 0.87) in “Sufaid” with RSA which show that there

existed a relationship between the two parameters.

Results of PPO activity show highly significant effects of high concentrations of

AA and CA on PPO activity compared to control. It may be that AA inhibited browning

by reducing the o-quinones whereas CA inhibited PPO due to its chelating action. These

results are also supported by the positive correlation between PPO and BI (r = 0.95,

0.67 for Surkh while r =0.70 and 0.72 for Sufaid during both years respectively.

Results of TP content show that both high concentrations of AA and CA

effectively maintained the TP content compared to control. According to Gil et al.

Deleted:

264

(1998), 2% AA effectively prevented decrease in the levels of TP of ‘Fuji’ apple during

storage. Browning index was low in higher concentrations of both AA and CA while

maximum BI during both years in both cultivars was recorded in control. A simple

explanation may be that both higher concentrations inhibited the activity of PPO which

prevented the oxidation of phenolic compounds.

The results regarding REC reveal highly significant effect of AA compared to CA

concentrations on both loquat cultivars during storage. The REC continually increased

during storage which depicts decomposition of cell membrane and increasing

senescence of the tissue. During stress conditions, electrolytes leak into surrounding

tissues therefore high conductivity indicates leakage of intracellular ions (Ade-Omowaye

et al., 2003). Results show that the antioxidant properties of AA helped to scavenge the

harmful free radicals and keeping the membranes intact, which reduced electrolyte

leakage compared to CA treatment. These results are also supported by the highly

significant negative correlation between EC and RSA (p < 0.05), r = -0.88 and -0.86 for

Surkh and r =-0.80 and -0.75 for Sufaid during both years respectively.


265

SUMMARY

Loquat (Eriobotrya japonica Lindl.) fruit is liked for its distinct sourness,

sweetness and aroma and also because it is an early season fruit (Amaros et al., 2008),

however it has a short life after harvesting. Apart from the fact that it easily decays, it

also is prone to nutritional and moisture losses (Ding et al., 2002). The use of cold stores

may increase its shelf life but do not retain its initial quality (Ding et al., 1998a). To

enhance the postharvest period of such perishable fruits it is therefore vital to find other

possible techniques.

Keeping in view the above problems, three comprehensive studies were

performed to determine the effectiveness of different packages and dipping solution

treatments including high density polyethylene (HDPE) with 0.09mm thickness, low

density polyethylene (LDPE) of 0.03 mm thickness, 0.25% perforated HDPE and LDPE,

dipping treatments with 1%, 2% , 3% calcium chloride, 250 mg/l, 500 mg/l and 750

mg/l concentrations of ascorbic acid and citric acid. Two local cultivars of loquat

(“Surkh” and “Sufaid”) were selected for the study. Fruit was harvested at mature ripe

stage and after applying the treatments, fruits were stored at 4˚C in a cold store. Changes

in total soluble solids, browning index, firmness, ascorbic acid, titratable acidity,

electrolyte leakage, total soluble proteins, polyphenols, polyphenol oxidase, superoxidase

dismutase, peroxidase, catalase and total antioxidants as affected by different treatments

were studied.

For the first part of study, different polyethylene packages were evaluated. The

analytical results revealed:

Formatted: Space Before: 0 pt,After: 0 pt

Deleted: ¶

Deleted: ¶

266

HDPE had high SOD, CAT activity, maximum TA, AA content, total sugars,

reducing sugars, non reducing sugars, high BI and low TSS, POD activity and

weight loss in both cultivars.

LDPEP and LDPE had high firmness, low SOD and PPO activity. LDPEP

retained maximum TSS.

Both perforated packages had more weight losses than non perforated treatments.

Non perforated packages had high RSA,TP, POD activity. BI was high in control

and HDPE. LDPE had the lowest BI. Control had high EC in both cultivars.

The study regarding the effect of calcium chloride treatments on storage life of loquat

showed that

1 % CaCl2 treatment did not show significant effect on quality parameters

compared with control treatment.

2% CaCl2 had high firmness, RSA, SOD, CAT activity and low PPO, POD

activity and EC while in addition to the above parameters 3% CaCl2 retained

maximum firmness, TSS, TP content, reducing, non reducing and total sugars,

lowest BI and weight loss up to 4-5 weeks in both cultivars

3% CaCl2 retained maximum firmness, TSS, TP content, highest reducing, non

reducing and total sugars, lowest BI and weight loss.

The study of the effect of anti browning agents on the keeping quality of loquat fruit

revealed the following facts.

Formatted: Line spacing: Double

Formatted: Line spacing: Double

267

Higher concentrations of Ascorbic acid held fruit quality much better then citric

acid for up to 4-5 weeks.

Higher concentrations of both Ascorbic acid and Citric acid reduced browning

significantly.

Ascorbic acid content of both cultivars was not effected by antibrowning agents

during both year, however all treatments differed significantly from control.

Reducing, non reducing and total sugars were not effected by anti browning

agents in both cultivars.

RECOMMENDATIONS

Overall, this work demonstrates that use of non perforated packages, 3% calcium

chloride, 500 mg/l and 750 mg/l concentrations of both Ascorbic acid and Citric acid

can successfully be used to increase the shelf life and reduce the browning incidence in

loquat during cold storage. This study opens a doorway to explore the effectiveness of

other concentrations of these GRAS antioxidants alone and in combination to investigate

more efficient postharvest technology.

Deleted: ¶

Deleted: ¶

268

LITERATURE CITED

Abbasi, N.A., M.M. Kushad and A. G. Endress. 1998. Active Oxygen-scavenging

enzymes activities in developing apple flowers and fruits. Scientia Horticulturae,

74: 183-194.

Abbasi, N.A. and M.M. Kushad. 2006. The activities of SOD, POD and CAT in ‘Red

Spur Delicious’ apple fruits are affected by DPA but not calcium in postharvest

drench solutions. J. Amer. Pomo. Soc., 60(2): 84-89.

Abbasi, N.A., Z. Iqbal, M. Maqbool and I. A. Hafiz. 2009. Postharvest quality of mango

(Mangifera indica l.) fruit as affected by chitosan coating. Pak. J. Bot., 41(1):

343-357, 2009.

Abbott, J. A. 1999. Quality measurement of fruits and vegetables. Postharvest Biology

and Technology, 15: 207–225.

Abbott, J.A. and F.R. Harker. 2003. Texture. In: Gross, K.C., C. Y. Wang, and M.

Saltveit (Eds.). The commercial storage of fruits, vegetables, florist, and nursery

stock: Agricultural handbook 66. USDA, ARS.

Adam, Z., A. Borochov, S. Mayak, and A.H. Halevy. 1983. Correlative changes in

sucrose uptake, ATPase activity and membrane fluidity in carnation petals during

senescence. Physiol Plant. 58:257-262.

Adegoke, G.O., M.N. Kumar, A.G. Gopalakrishna, M.C. Vardaraj, K. Sambaiah, B.R.

Lokesh. 1998. Antioxidants and lipid oxidation in food—a critical appraisal. J.

Food Sci. Technol., 35:283–98.

269

Ade-Omowaye, B.I.O., K.A. Taiwo, N. M. Eshtiaghi, A. Angersbach and D. Knorr.

2003. Comparative evaluation of the effects of pulsed electric field and freezing

on cell membrane permeabilisation and mass transfer during dehydration of red

bell peppers. Innovative Food Science and Emerging Technologies, 4:177–188.

Aderiye, B.I. 1985. Effects of ascorbic acid and pre-packaging on shelf-life and quality of

raw and cooked okra (Hibiscus esculentus) . Food Chemistry, 16(1):69-77.

Agar, I.T., R. Massantini, B. H. Pierce and A. A. Kader. 1999. Postharvest CO2 and

Ethylene Production and Quality Maintenance of Fresh-Cut Kiwifruit Slices. J.

Food Sci., 64(3):433-440.

Ahvenainen, R. 1996. New approaches in improving the shelf life of minimally processed

fruit and vegetables. Trends in Food Sci. and Tech., 7:179–187.

Akbudak, B. and A. Eris. 2004. Physical and chemical changes in peaches and nectarines

during the modified atmosphere storage. Food Control, 15: 307–313.

Al-Ati, T and J.H. Hotchkins. 2002. Application of packaging and modified atmosphere

to fresh cut fruits. In: Fresh cut fruits and vegetables. Science, technology and

market. Edited by O. Lamikanra. Boca Raton. CRC press, p. 305-338.

Altunkaya, A. and V. Gokmen. 2008. Effect of various inhibitors on enzymatic

browning, antioxidant activity and total phenol content of fresh lettuce (Lactuca

sativa). Food Chemistry, 107: 1173–1179.

Amaros, A., M.T. Pretel, P. J. Zapata, M.A. Botella, F. Romojaro and M. Serrano.

2008. Use of modified atmosphere packaging with microperforated polypropylene

films to maintain postharvest loquat fruit quality. Food Sci. and Tech. Intl.,

14(1):95-103.

270

Amin, A., M. Ali, A. Ahmed and M. Hassan. 2001. Effect of coatings and polyethylene

sheet the shelf life of mangoes (Mangifera indica L.). Pak. J. Arid Agric.,

4(1-2): 7-13.

Andres, S.C., L. Giannuzzi and N.E. Zaritzky. 2002. Quality parameters of packaged

refrigerated apple cubes in orange juice. Lebensmittel-Wissenschaft Und-

Technologie, 35: 670–679.

Anonymous. 2006. Loquat Fruit Facts . (http://www.crfg.org/pubs/ff/loquat.html).

Searched on 05-05-2006.

Antolovich, M., P.D. Prenzler, E. Patsalides, S. McDonald and K. Robards. 2001.

Methods for testing antioxidant activity. Analyst, 127: 183–198.

Armitage, A.M. and J. M. Laushman. 2003. Helianthus annuus L. – Annual Sunflower.

In: Specialty Cut Flowers. The production of annuals, perennials, bulbs, and

woody plants for fresh and dried cut flowers. 2nd ed. Timber Press. Portland,

OR., p. 319-330.

Ascherio, A., E.B. Rimm, E. L. Giovannucci, G.A. Colditz, B. Rosner, W.C. Willet,

F.Sacks and M.J.A. Sampers. 1992. Prospective study of nutritional factors and

hypertension among US men. Circulation, 86:1475-1484.

Assimopoulou, A.N., S.N. Zlatanos and V.P. Papageorgiou. 2005. Antioxidant activity

of natural resins and bioactive triterpenes in oil substrates. Food Chemistry,

92: 721–727.

Attia, M. M. 1995. Effect of post harvest treatments on fruit losses and keeping quality of

Balady oranges through cold storage. Alexandria J. Agri. Res., 40 (3): 349 – 363.

(CAB Abstracts 1996 -1998/ 07).

271

Award, M.A., A. D. Jager, V.D. Plas, A.R. Van der Krol. 2001. Flavonoid and

chlorogenic acid changes in skin of ‘Elstar’ and ‘Jonagold’ apples during

development and ripening. Scientia Hort., 90: 69–83.

Aydin, N. and A. Kadioglu. 2001. Changes in the chemical composition, polyphenol

oxidase and peroxidase activities during development and ripening of Medlar

fruits (Mespilus germanica L.). Bulg. J. Plant Physiol., 27(3–4): 85–92.

Ayranci, E. and S. Tunc. 2004. The effect of edible coatings on water and vitamin C

loss of apricots (Armeniaca vulgaris Lam.) and green peppers (Capsicum annuum

L.). Food Chemistry, 87: 339–342.

Bajji, M., J. Kinet and S. Lutts. 2002. The use of the electrolyte method for assessing cell

membrane stability as a water stress tolerance test in durum wheat. Plant Growth.

Regul., 36: 61–70.

Ball, J.A. 1997. Evaluation of two lipid based edible coating for their ability to preserve

post harvest quality of green bell peppers. Master Diss., Faculty of the Virginia

Polytecnic Institute and state University, Blacksburg, Virginia, USA.

Banaras, M., P.W. Bosland and N.K.Llownds. 2005. Effects of harvest time and growth

conditions on storage and post-storage quality of fresh peppers (capsicum annuum

l.). Pak. J. Bot., 37(2): 337-344.

Bangarth, F. 1979. Calcium-related physiological disorders of plants. Ann. Rev. Phytopathol. 17: 97-122.

Bannister, J.V., W. H. Bannister, and G. Rotilio. 1987. Aspects of the structure, function,

and application of superoxide dismutase. CRC Rev. Biochem., 22: 118-180.

Banwart, G. J. 1989. Basic Food Microbiology, 2nd ed., New York, Van Nostrand,

Reinhold. p. 603–604.

272

Barth, M. M. and H. Zhang. 1996. Packaging design effects antioxidant vitamin retention

and quality of broccoli florets during postharvest storage. Postharvest biology

and technology, 9: 141-150.

Bartosz, G. 1997. Oxidative stress in plants. Acta Physiologiae Plantorum, 19(1): 47-64.

Batu, A. and A. K. Thompson. 1998. Effects of Modified Atmosphere Packaging on

Post Harvest Qualities of Pink Tomatoes. Tr. J. of Agriculture and Forestry,

22: 365-372.

Beaudry, R.M. 1999. Effect of O2 and CO2 partial pressure on selected phenomena

affecting fruit and vegetable quality. Postharvest Biology and Technology.

15:293-303.

Beaudry, R. M. 2002. Responses of horticultural commodities to low oxygen limits to the

expanded use of modified atmosphere packing. Hort. Technology, 10:491-500.

Ben-Yehoshua, S. 1985. Individual seal-packaging of fruit and vegetables in plastic film

– a new postharvest technique. HortScience, 20:32-37.

Ben-Yehoshua, S., B, Shapiro, Z.E. Chen and S. Lurie. 1993. Mode of action of plastic

film in extending life of lemon and bell pepper fruits by alleviation of water

stress. Plant Physiology, 73: 87- 93.

Ben-Yehoshua, S., Peretz, J., Moran, R., Lavie, B. and Kim, J.J., 2001. Reducing the

incidence of superficial flavedo necrosis (nuxan) of ‘Shamouti’ oranges (Citrus

sinensis, Osbeck). Postharvest Biol. Technol. 22:19–27.

Beuchat, L. R. and Golden, D. A. 1989 Antimicrobials occurring naturally in foods. Food

Technol, 43: 134–142.

273

Beyer, W.F. and I. Fridovich. 1987. Catalases – with and without heme. In: oxygen

radicals in biology and medicine. M.G. Simic, K.A. Taylor, J.F.Ward and C. Von

Sonntag (Eds). New York: Plenum Press, p. 651-661.

Bhattarai, D.R. and D. M. Gautam. 2006. Effect of harvesting method and calcium on

post harvest physiology of tomato. Nepal Agric. Res. J., 7: 37-41.

Bidabe, B. 1970. Apple quality in relation to picking and eating time. Aroboric fruit,

17 (196) : 26-28.

Blokhina, O., E. Virolainen and K.V. Fagerstedt. 2003. Antioxidants, oxidative damage

and oxygen deprivation stress: a review. Annals of Botany, 91:179-194.

Borochov, A. and R. W. Woodson. 1989. Physiology and biochemistry of flower petal

senescence. Hort. Rev. 11:15-43.

Bowler, C., M.V. Montague and D. Inze. 1992. Superoxide dismutases and stress

tolerence. Ann. Rev. of Plant. Physiol. and Plant Mol. Bio., 43:83-116.

Bradford, M.M. 1976. A rapid sensitive method for the quantification of microgram

quantities of protein utilizing the principle of protein-dye binding. Anal.

Biochem., 72:248-254.

Brand-Williams, W., M.E. Cuvelier and C. Berset. 1995. Use of free radical method to

evaluate antioxidant activity. Lebensmittel Wissenschaft und Technologie,

28: 25–30.

Brennan, M., L. G. Port and R. Gormley. 2000. Post-harvest Treatment with Citric Acid

or Hydrogen Peroxide to Extend the Shelf Life of Fresh Sliced Mushrooms.

Lebensmittel-Wissenschaft und -Technologie, 33 (4): 285-289.

Formatted: Bullets and Numbering

274

Britton, G. 1995. Structure and properties of carotenoids in relation to function. FASEB

J., 9: 1551- 1558.

Bryant, P. 2004. Optimising the Postharvest Management Of Lychee (Litchi chinensis

Sonn.) – A Study of Mechanical Injury and Desiccation. Ph.D. Thesis. The

University of Sydney. 24 pp.

Burris, R.H. 1960. Hydroperoxidase (peroxidases and catalases). In: W. Ruhland

(Editor), Encyclopedia of Plant Physiology, Vol. 12. Springer-Verlag, Berlin,

p. 365-400.

Caballero, P. and M.A. Fernández. 2003. Loquat, production and market. First

International Symposium on Loquat, 11–13 April 2002, Valencia (Spain). Options

Mediterranean’s: Série A. Séminaires Méditerranéens, 58: 11–20.

Cadenas E .1989. Biochemistry of oxygen toxicity. Annu. Rev. Biochem., 58: 79-110.

Cai, C., K.S. Chen, W.P. Xu, W.S. Zhang, X. Li and I. Ferguson. 2006a. Effect of

1-MCP on postharvest quality of loquat fruit. Postharvest Biology and

Technology, 40:155-162.

Cai, C., X. Li and K. S. Chen. 2006b. Acetylsalicylic acid alleviates chilling injury of

postharvest loquat (Eriobotrya japonica L.) fruit. Eur Food Res Technol.,

223: 533–539.

Cai C.,C. J. Xua, X. Li, I. Ferguson and K.S. Chena. 2006c. Accumulation of lignin in

relation to change in activities of lignification enzymes in loquat fruit flesh after

harvest Postharvest Biology and Technology, 40: 163-169

275

Cai, C, C. J. Xu, L. L. Shan, X. Li, C. H. Zhou, W. S. Zhang, I. Ferguson and K.S.

Chen. 2006d. Low temperature conditioning reduces postharvest chilling injury in

loquat fruit. Postharvest Biology and Technology, 41: 252–259.

Campos, P.S., V. Quartin, J.C. Ramalho and M.A. Nunes. 2003. Electrolyte leakage and

lipid degradation account for cold sensitivity in leaves of Coffea sp. plants. J. Pl.

Physiol., 160: 283-292.

Cappellini, R.A. and M.J. Ceponis. 1984. Postharvest losses in fresh fruits and

vegetables. In: H.E., Moline (Ed.), Postharvest pathology of fruits and vegetables:

postharvest losses in perishable crops, vol. 1914. Univ. Calif. Bull., p. 24–30.

Chachin, K. and H. Hamauzu. 1997. Loquat: Postharvest physiology and storage of

tropical and subtropical fruits. CAB Intl., p. 397-403.

Chardonnet, C.O., C. S. Charron, C.E. Sams and W.S. Conway. 2003. Chemical changes

in the cortical tissue and cell walls of calcium-infiltrated ‘Golden Delicious’

apples during storage. Postharvest Biology and Technology, 28: 97- 111.

Chen, F.H., G.B. WU and C.F. Li. 2003. Effects of modified atmosphere packaging

on respiration and quality attributes of loquat fruit during cold storage. Trans. Chi.

Soc. Agri. Engrr., 19(5): 147-151.

Cheour, F., J. Arul, J. Makhlouf and C. Willemot. 1992. Delay of membrane lipid

degradation by calcium treatment during cabbage leaf senescence. Plant

Physiology, 100: 1656-1660.

Christopher, H. S., F. Xuetong, A. P. Handel and K. B. Sokorai. 2003. Effect of citric

acid on the radiation resistance of Listeria monocytogenes and frankfurter quality

factors. Meat Science, 63(3):407-415.

276

Church, I., and A. Parsons. 1995. Modified atmosphere packaging technology: Review. J.

Sci. Food Agric. 67:143-152.

Chu, Y.H., L. Chang, and H. F. Hsu. 2000. Flavonoid content of several vegetables and

their antioxidant activity. Journal of the Science of Food and Agriculture,

80: 561–566.

Cliffe, B.V. and D. O’Beirne. 2005. Effects of chlorine treatment and packaging on the

quality and shelf-life of modified atmosphere (MA) packaged coleslaw mix. Food

Control, 16: 707–716.

Cocci, E. P. Rocculi, S. Romani and M. D. Rosa. 2006. Changes in nutritional properties

of minimally processed apples during storage. Postharvest Biology and

Technology, 39:265–271.

Collins, J. L., and A.G. Marangoni. 2000. Vegetables. In: G. L. Christen and J. S. Smith

(Eds.), Food chemistry: Principles and applications. CA: Science and Technology

Systems, 123 pp.

Conway, W.S., C.E. Sams, R.G. McGuire, and A. Kelman. 1992. Calcium treatment of

apples and potatoes to reduce postharvest decay. Plant Disease 76:329-334.

Craft, C.C., 1966. Localization and activity of phenolase in the potato tuber. Amer.

Potato J.43: 112-125.

Crane, J.H. and M. L. Caldeira. 2006. Loquat Growing in the Florida Home Landscape.

University of Florida, Institute of Food and Agricultural Sciences,

http://edis.ifas.ufl.edu. (searched on 24-08-2006).

277

Crumiere, F. 2000. Inhibition of enzymatic browning in food products using Bio-

Ingredients. M.Sc. Diss. Department Of Food Science And Agricultural

Chemistry. Mcgill University. Montreal, Québec.

Cuevas, J., I. M. Romero, M.D. Fernandez and J.J. Hueso. 2007. Deficit irrigation

schedules to promote early flowering in ‘Algerie’ loquat. Acta Hort. (ISHS)

750:281-286. http://www.actahort.org/books/750_44.htm.

Davey, M. W., M. V. Montagu, D. Inze, M. Sanmartin, A. Kanellis, N. Smirnoff, I.F.

Benzie, J.J. Strain, D. Favell and J. Fletcher. 2000. Plant L-ascorbic acid:

chemistry, function, metabolism, bioavailability and effects of processing. J. Sci.

Food and Agric., 89: 825–860.

Day, B.P.F. 1993. Fruit and Vegetables. In: Principles and Application of Modified

Atmosphere Packaging of Food. (R. Parry. ed) Blackie. Academic and

Professional. UK. London. p. 114-133.

Day, B. P. F. 1994. Modified atmosphere packaging and active packaging of fruits and

vegetables. In: Minimal processing of foods (VTT Symposium series 142),

Majvik, 14–15 April 1994.

De Martino, G., K. Vizovitis, R. Botondi, A. Bellincontro and F. Mencarelli. 2006.

1-MCP controls ripening induced by impact injury on apricots by affecting SOD

and POX activities. Postharvest Biology and Technology, 39: 38–47.

De Souza, A. L. B., S.D.Q.Scalon., M.I.F. Chitarra and A.B. Chitarra. 1999. Postharvest

application of CaCl2 in strawberry fruits (fragaria ananassa dutch cv. Sequóia):

evaluation of fruit quality and Postharvest life. Cienc. E Agrotec., Lavras.

23(4): 841-848.

278

Del Caro, A., A. Piga, V. Vacca and M. Agabbio. 2004. Changes of flavonoids, vitamin

C and antioxidant capacity in minimally processed citrus segments and juices

during storage. Food Chemistry, 84: 99–105.

Demarty, M., C. Morvan and M. Thellier. 1984. Ca and the cell wall. Plant Cell

Environ., 7: 441–448.

Devanand. L.L. and S. Mukhopadhyay. 2006. Influence Of Sample Preparation On Assay

Of Phenolic Acids From Eggplant. J. Agric. Food Chem., 54: 41-47.

Dhindsa, R.S., P. Dhindsa and T.A. Thorpe. 1981. Leaf senescence: correlated with

increased levels of membrane permeability and lipid peroxidation, and decreased

levels of superoxide dismutase and catalase. J. Exp. Bot. 32: 93–101.

Dhruba R. B. and D. M. Gautam. 2006. Effect of Harvesting Method and Calcium on

Post Harvest Physiology of Tomato. Nepal Agric. Res. J., 7: 37-40.

Dimitrios, G. and D. D. Pavlina. 2005. Summer-pruning and preharvest calcium chloride

sprays affect storability and low temperature breakdown incidence in kiwifruit.

Postharvest Biology and Technology, 36: 303–308.

Ding, C.K., K. Chachin and Y. Ueda. 1997. Effects of polyethylene bag packing and low-

temperature storage on physical and chemical characteristics of loquat fruit. In:

Kader A.A. (ed), Proc. 7th

Intl. Contr. Atmos. Res. Conf., Vol. 3, p. 177-184.

Ding,C. K., Chachin, Y. Hamauzu, Y. Ueda and Y. Imahori. 1998a. Effects of storage

temperatures on physiology and quality of loquat fruit. Postharvest Biology and

Technology, 14 (3): 309-315.

Ding,C. K., K. Chachin, Y. Ueda and Y. Imahori. 1998b. Purification and Properties of

Polyphenol Oxidase from Loquat Fruit. J. Agric. Food Chem., 46: 4144-4149.

279

Ding, C. K., Y.U. Chachin, Y. Ueda, Y. Imahori, and H. Kurooka. 1999. Effects of high

CO2 concentration on browning injury and phenolic metabolism in loquat fruits. J.

Jap. Soc. Hort. Sci., 68: 275–282.

Ding, C. K., Y. Chachin , Y. Youshinori and C. Wang. 2001. Inhibition of Loquat

enzymatic browning by Sulfhydryl compounds. J. Food Chemistry, 76:213-218.

Ding, C.K., Y. Chachin, Y. Ueda, Y. Imahori and C.Y. Wang. 2002. Modified

atmosphere packaging maintains postharvest quality of loquat fruit. Postharvest

Biology and Technology, 24(3):341-348.

Ding. Z., S. Tian, Y. Wang, B.Li, Z. Chan, J. Hana and Y. Xua. 2006. Physiological

response of loquat fruit to different storage conditions and its storability.

Postharvest Biology and Technology, 41: 143-150.

Ding , CK. 2007. Loquat :Produce Quality and Safety Laboratory, USDA/ARS .

http://www.ba.ars.usda.gov/hb66/088loquat.pdf. searched on 10-03-2007.

Dole, J.M. and H.F. Wilkins. 2005. Helianthus.. In: Floriculture: Principles and Species.

2nd ed. Pearson Education, Inc., Upper Saddle River, NJ., p.567-573.

Dong, Li. , H.W. Zhou, L. Sonega, A. Lers and S. Lurie. 2001. Ripening of “Red Rosa”

plums: effect of ethylene and 1-methylcyclopropane. Aust. J. Plant. Physiol.,

28:1039-1045.

Dubey, R.S. 1997. Photosynthesis in plants under stressful conditions. In: Pessaraki, M.,

ed. Handbook of Photosynthesis. New York, N.Y. Marcel Dekker, Inc.,

p. 859-875.

Duke, I. and E.S. Ayensu. 1985. Medicinal plants of China. Vol. 2. Reference Publ,

Algonae, MI., 544 pp.


280

Durand, K. M. D. 2006. Modiefied atmosphere packages and postharvest quality of

pigeon pea. M.Sc. Diss. University of Porto Rico.

Eckert, J. W. 1991. Role of chemical fungicides and biological agents in postharvest

disease control. Biological control of postharvest diseases of fruits and vegetables.

Workshop Proceedings, Shepherdstown, USA, USDA- Agriculture Research

Services Publication, 92: 14-30.

Elez, M.P.,R.C. F. Soliva , S. Gorinstein and O.B. Martín. 2005 . Natural antioxidants

preserve the lipid oxidative stability of minimally processed avocado purée.

J. Food Sci., 70(5): (n.p)

El-hilali, F., A. Ait-Oubahou, A. Remah and O. Akhayat. 2003. Chilling injury and

peroxidase activity changes in “fortune” mandarin fruit during low temperature

storage. Bulg. J. Plant Physiol., 29(1–2): 44–54.

Enzyme Nomenclature (1992). Recommendation of the Nomenclature Cornmittee of the

International Union of Biochemistry. International Union of Biochemistry,

Academic Press, San Diego, CA., p.313-314.

Esmel, C.E. 2005. Influence of calcium on postharvest quality and yield of strawberry

fruit (fragaria×ananassa duch.). (M.Sc. Diss.). The graduate school of the

university of Florida. University of Florida.

Esparza, J. R., M. B. Stone, P. A. Kendall, C. Stushnoff, and E. Pilon-Smits. 2005.

Quality of fresh cut green leaf lettuce treated with ascorbic acid applied by two

hydrocooling methods. Session 36E-87, Fruit and Vegetable Products: General.

IFT Annual Meeting, July 15-20 - New Orleans, Louisiana., (n.p)

281

Exama, A., J. Arul, R.W. Lencki, L.Z. Leee and C. Toupin. 1993. Suitable of plastic

films for modified atmosphere packaging of fruits and vegetables. J. Food Sci.,

58: 1365 – 1370.

Fan, X. and K. J.B. Sokorai. 2005. Assessment of radiation sensitivity of fresh-cut

vegetables using electrolyte leakage measurement. Postharvest Biology and

Technology, 36:191–197.

Feng, G., H. Yang and Y. Li. 2005. Kinetics of relative electrical conductivity and

correlation with gas composition in modified atmosphere packaged bayberries

(Myrica rubra Siebold and Zuccarini). Food Sci. and Tech., 38(3): 249-254.

Fennema, O.R. 1996. Food Chemistry, 3rd Ed.; Marcel Dekker: New York, NY., 1996.

Ferguson, I.B. 1984. Calcium in plant senescence and fruit ripening. Plant Cell Environ.,

7:477-489.

Ferguson, I.B., R.K. Volz, F.R. Harker, C.B. Watkins, and P.L. Brookfield. 1995.

Regulation of postharvest fruit physiology by calcium. Acta Hort. 398:23-30.

Ferguson, I.B and L.M. boyd. 2002. Inorganic nutrients and fruit quality: Fruit quality

and its biological basis. Sheffield academic press. UK., p. 17-45.

Fernandez, J.P.T., J.F. Nock and C. B. Watkins. 2007. Antioxidant enzyme activities in

strawberry fruit exposed to high carbon dioxide atmospheres during cold storage.

Food Chemistry, 104: 1425–1429.

Fernandez, P.M.S., D. Villano, M.C. Garcia-Parrilla and A.M. Troncoso. 2004.

Antioxidant activity of wines and relation with their polyphenolic composition.

Analytica Chimica Acta, 513: 113–118.

282

Fernando, J.A.Z., S. Y. Wang, C.Y. Wang, A. G. Aguilar. 2004. Effect of storage

temperatures on antioxidant capacity and aroma compounds in strawberry fruit.

Lebensm.-Wiss. u.-Technol., 37: 687–695.

Foyer, C. H. 1993. Ascorbic acid. In: R. G. Alscher & J. L. Hess (Eds.), Antioxidants in

higher plants. Boca Raton, FL: CRC Press, p. 31–58.

Francois, A. T. and J.C. Espin. 2001. Phenolic compounds and related enzymes as

determinants of quality in fruits and vegetables. J. Sci. of food & Agri.,

81(9):853-976.

Freedman, L. and Francis, F.J., 1984. Effect of ascorbic acid on color of jellies. J. Food

Sci., 49(4): 212–1213.

Fridovich, I. 1978. The biology of oxygen radicals. Science, 201:875-880.

Fridovich, I., 1986. Superoxide dismutase. In: A. Meistor (Editor), Advances in

Enzymology and Related Areas of Molecular Biology, Vol. 58. John Wiley and

Sons, New York, p. 61-97.

Fry, S.C., 2004. Primary cell wall metabolism: tracking the careers of wall polymers in

living plant cells. New Phytol., 161: 641–675

Gaspar, T., C. Perel, T.A. Thorpe and H. Greppin. 1981. Peroxidases. University of

Geneva Press, Geneva.

Geeson, J.D., K. Maddison and K. M. Browne. 1981. Modified Atmosphere Packaging of

Tomatoes. In Packaging of Horticultures Produce. AAB/NCAE Residential

Meeting. London. p.8-15.

Gekas,V., F.A.R. Oliveira and G.H. Crapiste. 2002. Engineering and food for the 21st

century. Boca Raton: CRC Press., p. 193-215.


283

Gil, M. I., J.R. Gorny and A.A. Kader. 1998. Responses of ‘Fuji’ apple slices to ascorbic

acid treatments and low-oxygen atmospheres. HortScience, 33: 305–309.

Glenn, G. M. and B.W. Poovaiah. 1990. Calcium-mediated postharvest changes in

texture and cell wall structure and composition in ‘‘Golden delicious’’ apples. J.

Amer. Soc. Hort. Sci., 1:15 - 19.

Gong, Y., P. M. A. Toivonen, O.L. Lau and P.A. Wiersma. 2001. Antioxidant system

level in ‘Braeburn” apple is related to its browning disorder. Bot. Bull. Acad. Sin.,

42:259-264.

Gonzalez, A., C. S. R. Cruza, R. C. Valenzuelaa, A. R. Flelixa, C.Y. Wang. 2004.

Physiological and quality changes of fresh-cut pineapple treated with

antibrowning agents. Lebensm.-Wiss. u.-Technol., 37: 369–376.

Gonzalez, A., C. S.R. Cruza, S.V. Herlinda, O.V. Francisco, R. P. Aguilar and C.Y.

Wang. 2005. Biochemical changes of fresh-cut pineapple slices treated with

antibrowning agents. Int. J. Food Sci. and Tech., 40: 377–383.

GOP, 2007. Fruit, Vegetable and Condiments. Statistics of Pakistan. Ministry of Food,

Agri. and Livestock (Economic Wing). Govt. of Pakistan, p.1-2 .

Gorny, J. R. 1997. Summary of CA and MA requirements and recommendations for

fresh-cut fruits and vegetables. In: CA 97 proceedings: Fresh Cut Fruits and

Vegetables and MAP. Davis, USA.

Gorny, J. R., B. H. Pierce, R.A. Cifuentes and A. A. Kader. 2002. Quality changes in

fresh-cut pear slices as affected by controlled atmospheres and chemical

preservatives. Postharvest Biology and Technology, 24 : 271–278.

284

Gorny, J.R., B. H..Pierce and A.A. Kader. 1999. Quality Changes in Fresh-cut Peach and

Nectarine Slices as Affected by Cultivar, Storage Atmosphere and Chemical

Treatments. J. Food Sci., 64 (3): 429-432.

Greppin, H., C. Penel, T. Gaspar. 1986. Molecular and Physiological Aspects of Plant

Peroxidases. Geneve: University Geneva, 468 pp.

Gunes, G., J. H. Hotchkiss and C. B. Watkins. 2001. Effects of gamma irradiation on the

texture of minimally processed apple slices. J. Food Sci., 66: 63–67.

Gustavo, A. G., S.R. Cruz, H. S. Valdez, F. V. Ortiz, R. P. Aguilar and C.Y. Wang.

2005. Biochemical changes of fresh-cut pineapple slices treated with

antibrowning agents. International Journal of Food Science and Technology,

40: 377–383.

Guzman, I.L., M. Cantwell and D. M. Barrett. 1999. Fresh-cut cantaloupe: Effects of

CaCl2 dips and heat treatments on firmness and metabolic activity. Postharvest

Biology and Technology,17(3):201-213.

Haffner, K., H.J. Rosenfeld, G. Skrede and L. Wang. 2002. Quality of red raspberry

Rubus idaeus L. cultivars after storage in controlled and normal atmospheres.

Postharvest Biology and Technology, 24: 279–289.

Hagerman, A.E. 2002. Hydrolyzable tannin structural chemistry; Tannin handbook.

http://www.users.muohio.edu/hagermae/tannin.pdf. (accessed Mar 2007).

Haila, K. 1999. Effects of Carotenoids and Carotenoid-Tocopherol Interaction on Lipid

Oxidation In Vitro. 1) Scavenging of Free Radicals. 2) Formation and

Decomposition of Hydroperoxides (Diss.). EKT-series 1165. University of

Helsinki. Department of Applied Chemistry and Microbiology.

285

Halevy, A.H. and S. Mayak. 1981. Senescence and postharvest physiology of cut flowers

– Part 2. Hort. Rev., 3:59-143.

Halliwell, B. and J.M.C. Gutteridge. 1989. Free radicals in biology and medicine.

Clarendon press, Oxford, (n.p)

Halliwell, B. and J. M.C. Gutteridge. 1995. Free radicals in biology and medicine. 2nd

ed. Clarendon. Press, Oxford, UK. 543 pp.

Hamada, A., S. Yoshioka, D. Takuma, J. Yokota, T. Cui, M. Kusunose, M. Miyamura, S.

Kyotani and Y. Nishioka. 2004. The effect of Eriobotrya japonica seed extract on

oxidative stress in adriamycin-induced nephropathy in rats. Biological and

Pharmaceutical Bulletin, 27(12): 1961-1964.

Hamauzu, Y. 2006. Role and evolution of fruit phenolic compounds during ripening and

storage. Stewart Postharvest Review, p. 2-5.

Hans, Y.S.H. 1992. The guide book of food chemical experiments, Pekin Agricultural

University Press, Pekin.

Harel, E., Mayer, A. M. and Shah, Y. 1964. Catechol oxidases fiom apples, their

properties, subcellular location and inhibition. Physiol. Plant., 17:921-929.

Hashim, M.S., S. Lincy, V. Remya, M. Teena, and L. Anila. 2005. Effect of

polyphenolic compounds from Coriandrum sativum on H2O2-induced oxidative

stress in human lymphocytes. Food Chemistry, 92: 653–660.

Hassan, H. M. and J.G. Scandalios, 1990. Superoxide dismustase in aerobic organisms.

Stress responses in plants: Adaptation and acclimation mechanisms. Wiley-Leiss,

Inc. USA, p. 175-189.


286

Hayashi, A., N. Taniguchi, K. Tsujimoyto and I. Kubo. 2007. Mass Spectrometric

Elucidation of Phenolic Oxidation Processes with Cu2. J. Mass Spectrom. Soc.

Jpn., 55(1) : 7-13.

Hebert, C., M.T. Charles, L. Gauthier, C. Willemot, S. Khanizadeh and J. Cousineau.

2002. Strawberry proanthocyanidins: Biochemical markers for Botrytis cinerea

resistance and shelf-life predictability. Acta Hort., 567: 659–662.

Hewajulige, I. G. N., R.S. Wilson-Wijeratnam, R. L.C. Wijesundera and M. Abeysekere.

2003. Fruit calcium concentration and chilling injury during low temperature

storage of pineapple. J. Sci. Food and Agric., 83: 1451–1454.

Hodges, D.M. 2003. Postharvest oxidative stress in horticultural crops. Foods products

press. The Howerth press. Binghampton. N.Y.

Hoehn, E., F. Gasser, B. Guggenbuhl, U. Kunsch. 2003. Efficacy of instrumental

measurements for determination of minimum requirements of firmness, soluble

solids, and acidity of several apple varieties in comparison to consumer

expectations. Postharvest Biology and Technology, 27: 27-37.

Holdsworth, S. D. 1988. Conservacion de frutas y hortalizas. Zaragoza: Acribia. 12 pp.

Holetzky, S. 2005. www.what are antioxidants. Searched on 16-02-2005. 45 pp.

Horwitz, W. 1960. Official and tentative methods of analysis. Ed.9. Association of

Official Agricultural Chemists, Washington, D.C., p. 314-320.

Hussain, A., N.A. Abbasi and A. Akhtar. 2007. Fruit characteristics of different loquat

genotypes in Pakistan. Proc. IInd Intl. Sym. On Loquat. Acta Hort.,

750: 287-291.


287

IQS, 2005. Industrial Quick Search, Inc. www.plastic-bags.net/info/index.htm.

Searched on 12-03-2005.

Ito, H., E. Kobayashi, S.H. Li, T. Hatano, D. Sugita, N. Kubo, S. Shimura, Y. Itoh, H.

Tokuda, and H. Nishino. 2002. Antitumor activity of compounds isolated from

leaves of Eriobotrya japonica. J. Agric. Food Chem. Washington, D.C. American

Chemical Society, 50 (8): 2400-2403.

Itzhaki, H., A. Borochov, and S. Mayak. 1990. Age-related changes in petal membrane

from attached and detached rose flower. Plant Physiol., 94:1233-1236.

Jayathunge, L. and C. Illeperuma. 2005. Extension of postharvest life of oyster

mushroom by modified atmosphere packaging technique. J. Food Sci., 70: 573 –

578.

Ji, L.L., F.W. Stratman and H.A. Lardy. 1988. Antioxidant enzyme systems in rat liver

and skeletal muscle. Arch. Biochem. Biophys., 263: 150–160.

Jiang, Y. M., J.R. Fu, G. Zauberman and Y. Fuchs. 1999. Purification of polyphenol

oxidase and the browning control of litchi fruit by glutathione and citric acid. J. of

Sci. and Food Agri., 79: 950–954.

Jiang, Y., L. Pen. and J. Li. 2004. Use of citric acid for shelf life and quality

maintenance of fresh-cut Chinese water chestnut. J. of Food Engineering, 63:

325–328.

Jimenez, A., J.A. Hernández, L. A. del Rio and F. Sevilla. 1997. Evidence for the

presence of the ascorbate–glutathione cycle in mitochondria and peroxisomes of

pea leaves. Plant Physiol., 114: 275–284.

288

Jose, A.G.B., B.G. Swansonb and G.V. Barbosa-Ca novasa. 2005. Inhibition of

polyphenoloxidase in mango puree with 4-hexylresorcinol, cysteine and ascorbic

acid. LWT. 38: 625–630.

Joyce D. and Patterson B. 1994. Postharvest water relations in horticultural crops:

principles and problems. ACIAR Proceedings, 50: 228-238.

Kader, A. 1986. Biochemical and physiological basis for effect of controlled and

modified atmospheres on fruits and vegetables. Food Technol., 40: 99-105.

Kader, A.A., D. Zargorg and E.L. Kerbel. 1989. Crit. Rev., Food. Sci. Nutr., 28: 1-30.

Kader, A. A. 1997. Biological bases of O2 and CO2 effects on postharvest- life of

horticultural perishables. In M. E. Saltveit (Ed.), Proc. of international controlled

atmosphere research conference. CA., 4:160–163.

Kader, A.A. 2002a. Recommendations for maintaining postharvest quality. Post harvest

Technology Research Information Center. Dept of Pomology. Univ. of California.

One Shield Ave., Davis, CA., 95616-8683.(n.p.)

Kader A.A. 2002b. fruits in global market: Fruit quality and its biological basis. Sheffield

academic press. UK. p. 1-14.

Kandhari, P. 2004. Generic differences in antioxidant concentration in the Fruit tissues of

four major cultivars of apples. (M.Sc. Diss). University of Maryland.

Kang, J H., S.P. Chawla, C. Jo, J.H. Kwon and M.W. Byun. 2005. Studies on the

development of functional powder from citrus peel. Bio resource Technology,

97(4): 614-620.


289

Karadeniz, T. 2003. Loquat (Eriobotrya japonica Lindl.) growing in Turkey. In: Llacer,

G.(Ed) , Badenes, M. L. (Ed) . International first symposium of loquat. Zaragoza:

Ciheam-iamz, p. 27-28.

Karakas, B. and F. Yıldız. 2007. Peroxidation of membrane lipids in minimally processed

cucumbers packaged under modified atmospheres. Food Chemistry,

100: 1011–1018.

Karakaya, S., S.N. El. and A.A. Tac. 2001. Antioxidant activity of some foods containing

phenolic compounds. Int. J. Food Sci. Nutr., 52: 501–508.

Kaur, C. and H.C. Kapoor. 2001. Antioxidants in fruits and vegetables-the millennium’s

health. Int. J. Food Sci. Tech., 36:703–25.

Kawakami, S., M. Mizuno and H. Tsuchida. 2000. Comparison of Antioxidant Enzyme

Activities between Solanum tuberosum L. Cultivars Danshaku and Kitaakari

during Low-Temperature Storage. J. Agric. Food Chem., 48: 2117-2121.

Kaynara, H., M. Merala, H. Turhanb, M. Kelesc, G. Celikb and F. Akcayb. 2005.

Glutathione peroxidase, glutathione-S-transferase, catalase, xanthine oxidase, Cu–

Zn superoxide dismutase activities, total glutathione, nitric oxide, and

malondialdehyde levels in erythrocytes of patients with small cell and non-small

cell lung cancer. Cancer Letters, 227: 133–139.

Kays, J. S. 1991.Postharvest physiology of perishable plant products., Van Nostrand and

Reinhold. Book. Publishing Co., New York, 532 pp.

Khan, I. 2003. The history of loquat growing and future prospects of its commercial

cultivation and marketing in Pakistan. Proc. First Int. Loquat Symp. Options

Mediterraneennes, 58: 25-26.

290

Kim, B.S. and A. Klieber . 1999. Quality maintenance of minimally processed Chinese

cabbage with low temperature and citric acid dip. J. Sci. of Food and Agri.,

75(1):31-36.

Kim, J. G., L. Yaguang and C.G.Kenneth. 2004. Effect of package film on the quality of

fresh-cut salad Savoy. Postharvest Biology and Technology, 32(1): 99-107.

Kim, Y. 2005. Changes In Polyphenolics And Resultant Antioxidant Capacity In

Tommy Atkins’ Mangos (Mangifera Indica L.) By Selected Postharvest

Treatments. (M.Sc. Diss). The Graduate School of The University Of Florida.

King, G.A, K.M. Davis, R.J. Stewart and W.M. Borst. 1995. Similarities in gene

expression during the postharvest induced senescence of spears and natural foliar

senescence of asparagus. Plant Physiology, 108: 125-128.

Kirkby. E. A. and D.J. Pilbeaam. 1984. Calcium as a plant nutrient. Plant cell Environ.

7:397 - 405.

Klien, J.D. and S. Lurie. 1994. Time, temperature and calcium interact in scald reduction

and firmness retention in heated apples. Hort. Science, 29: 194-195.

Kondo, S., H. Yoshikawa, R. Katayama. 2004. Antioxidant activity in astringent and non-

astringent persimmons. J. Hort. Sci. Biotech., 79, 390–394.

Kondo, S., K. Monrudee and K. Sirichai. 2005. Preharvest antioxidant activities of

tropical fruit and the effect of low temperature storage on antioxidants and

jasmonates. Postharvest Biology and Technology, 36: 309–318.

Krinsky, N.I. 1992. Mechanism of action of biological antioxidants. Proc. Soc. Exp. Biol.

Med., 20: 248-254.

291

Kulkarni, A.P., and S. M. Aradhya. 2005. Chemical changes and antioxidant activity in

pomegranate arils during fruit development. Food Chemistry, 93: 319–324.

Kwak, E.J and L. Seong. 2005. Inhibition of browning by antibrowning agents and

phenolic acids or cinnamic acid in the glucose–lysine model . J. Sci. of Food and

Agri., 85(8): 1337-1342.

Lamikanra, O. and M. A. Watson. 2007. Mild heat and calcium treatment effects on

fresh-cut cantaloupe melon during storage. Food Chemistry, 102(4): 1383-1388.

Lamikanra, O. and M. A. Watson. 2001. Effects of ascorbic acid on peroxidase and

polyphenoloxidase activities in fresh-cut Cantaloupe melon. J. Food Sci.,

66: 1283–1286.

Lamikanra, O., J.C. Banks and P. A. Hunter. 2000. Biochemical changes and microbial

changes during th storage of minimally processed cantaloupes. J. Agri and Food

Chem., 48:5955-5961.

Lara, I., P. García and M. Vendrell. 2004. Modifications in cell wall composition after

cold storage of calcium-treated strawberry (Fragaria × ananassa Duch.) fruit.

Postharvest Biology and Technology, 34(3): 331-339.

Larrigaudiere, C., I. Lentheric, E. Pinto, and M. Vendrell. 2001. Short term effects of air

and controlled atmosphere storage on antioxidant metabolism in Conference

pears. J. Plant Physiol., 158: 1015–1022.

Larson, R.A. 1988. The antioxidants of higher plants. Phytochemistry, 27:969-978.

Lattanzio, V., V.L.S. Palmieri, F. Christiaanand and S.Van. 1989.The beneficial effect of

citric and ascorbic acid on the phenolic browning reaction in stored artichoke

(Cynara scolymus L.) heads. Food Chemistry, 33(2):93-106.

292

Lattanzio, V. and Linsalata, V. 1989. The beneficial effect of citric acid and ascorbic acid

on the phenolic browning reaction in stored artichoke (Cynara scolymus L.)

Heads. Food Chem. 33, 93–106.

Lejaa, M., A. Mareczeka and J. Benb. 2003. Antioxidant properties of two apple cultivars

during long-term storage. Food Chemistry, 80: 303–307.

Leshem, Y.Y. 1992. Plant Membrane: A Biophysical Approach to Structure,

Development and Senescence. Kluwer Academic Publisher, Dordrecht. ISBN 0-

7923-1353-4.

Lester, G.E. and M.A. Grusak, 1999. Postharvest application of calcium and magnesium

to honeydew and netted muskmelons: Effects on tissue ion concentrations, quality

and senescence. J. Amer. Soc. Hort. Sci., 124: 545-552.

Lester, G.W. 2003. Oxidative stress affecting fruit senescence : Postharvest oxidative

stress in horticultural crops. Foods products press. The Howerth press.

Binghampton. N.Y., p.113 -130.

Lester, G. E., and M.A. Grusak. 2004. Field application of chelated calcium: postharvest

effects on cantaloupe and honeydew fruit quality. Hort Technology, 14: 29–38.

Lim- Byung, S., S. Choi, Lee, Y. kim and B. Moon. 1998. Effect of prowax- F coating on

keeping quality of “Tsugaru” apple during room and low temperature storage. J.

Hort. Sci., 40 (1): 96- 101.

Limbo, S. and L. Piergiovanni. 2006. Shelf life of minimally processed potatoes Part 1.

Effects of high oxygen partial pressures in combination with ascorbic and citric

acids on enzymatic browning. Postharvest Biology and Technology,

39: 254–264.

293

Lin S, R.H. Sharpe and J. Janick. 1999. Loquat: botany and horticulture. Hort Rev.,

23:233–276.

Lin, S. 2007. World loquat production and research with special reference to China. Acta

Hort., 750: 37-43.

Loaiza-Velade, J.G. and M.E. Saltveit. 2001. Heat shock applied either before or after

wounding reduce browning of lettuce leaf tissue. J. Amer. Soc. Hort. Sci.,

126:227-234.

Lopez,V.M.G. 2002. Inhibition of surface browning, cut avocado. J. of Food Quality,

26: 265-384.

Lu, C. and P.M.A. Toivonen. 2000. Effect of 1 and 100 kPa O2 atmmospheric pre-

treatments of whole ‘Sparton’ apples on subsequent quality and shelf life of slices

stored in modified atmosphere packages. Postharvest Biology and Technology,

18: 99-107

Lu, R. 2004. Multispectral imaging for predicting firmness and soluble solids content of

apple fruit. Postharvest Biology and Technology, 31: 147-157.

Luna-Guzman, I. and D.M. Barrett. 2000. Comparison of calcium chloride and calcium

lactate effectiveness in maintaining shelf stability and quality of fresh-cut

cantaloupe. Postharvest Biology and Technology, 19: 61–72.

Lurie, S. 2003. Antioxidants: Postharvest oxidative stress in horticultural crops. Foods

products press. The Howerth press. Binghampton. N.Y., p. 131 – 150.

Macheix, J.J., A. Fleuriet and J. Billot. 1990. Phenolic Compounds in fruit processing. In

Fruit Phenolics, CRC Press, Boca Raton, FL., p. 295-357.

294

Madinez, M.V. and J. R. Whitaker. 1995.The biochemistry and control of enzymatic

browning. Trends in Food Science and Technology, 6: 195-200.

Mahajan, B. V. C. and A. S. Dhatt . 2004. Studies on postharvest calcium chloride

application on storage behaviour and quality of Asian pear during cold storage .

Intl. J. Food, Agri. and Environment, 2(3-4): 157-159.

Mahmud, T.M., A. E. Raqeeb, R. S. Omar, A. R. Zaki and A. R. Al Eryani. 2008.

Effects of different concentrations and applications of calcium on storage life and

physicochemical characteristics of papaya (Carica Papaya L.). Amer. J.

Agric.and Bio. Sci., 3 (3): 526-533.

Manganaris, A., M. Vasilakakis, I. Mignani, G. Diamantidis and K. Tzavella-Klonari.

2005. The effect of preharvest calcium sprays on quality attributes,

physicochemical aspects of cell wall components and susceptibility to brown rot

of peach fruits (Prunus persica L. cv. Andross). Scientia Horticulturae,

107(1):4-50.

Manganaris, G.A., M. Vasilakakis, G. Diamantidis and I. Mignani. 2007. The effect of

postharvest calcium application on tissue calcium concentration, quality

attributes, incidence of flesh browning and cell wall physicochemical aspects of

peach fruits Food Chemistry, 100:1385–1392.

Maria, P.F. 2007. Storage life enhancement of avocado fruits. (Diss). McGill University.

Department of Bioresource Engineering. McGill University. Ste-Anne De

Bellevue, QC., Canada..

Marino, S. and I. Nogueras. 2003. Loquat, Eriobotrya japonica as a winter nectar source

for birds in central Spain. Ardeola, 50 (2): 265-267.

295

Marques, L., A. Fleuriet and J.J. Macheix. 1995. Fruit polyphenol oxidases: New data on

an old problem. In Enzymatic Browning and its Prevention, C.Y. Lee and J.R.

Whitaker (Eds.), ACS Syrnp. Ser. 600, Washington, DC., p. 90-102.

Martinez, M.V. and J. R. Whitaker. 1995. The biochemistry and control of enzymatic

browning. Trends Food Sci. Technol., 6: 195–200.

Martinsen, P. and P. Schaare. 1998. Measuring soluble solids distribution in kiwifruit

using near-infrared imaging spectroscopy. Postharvest Bioylogy and

Technology, 14: 271-281.

Mayer, A.M. 1987. Polyphenol oxidase and peroxidase in plants recent progress.

Phytochemistry, 26:11-20.

Mayer, A.M. and E. Harel. 1991. Phenol oxidases in fruits and vegetables. In: Food

Enzymology., .F. Fox (Ed.), Elsevier, London, p. 253-272.

Mazumdar,B.C. and K. Majumder. 2003. Methods on physico-chemical analysis of fruits.

Daya publishing house. Delhi., p. 124-125.

McCarthy, M. A. and R.H. Matthews. 1994. Nutritional quality of fruits and vegetables

subject to minimal processes. In R. C. Wiley (Ed.), Minimally processed

refrigerated fruits and vegetables. London: Chapman & Hall, p. 313–326.

McCord, J.M. 1994. Free radicals and pro-oxidants in health and nutrition. Food

McEvily, A.J., R. Iyengar and W.S. Otwell. 1992. Inhibition of enzymatic browning in

foods and beverages. Crit. Rev. Food Sci. Nutr., 32: 253-275.

McGlone, V.A. and S. Kawano. 1998. Firmness, dry-matter and soluble-solids

assessment of postharvest kiwifruit by NIR spectroscopy. Postharvest Biology

and Technology, 13: 131-141.

296

McNabb, K. and E. Takahashi. 2000. Freeze damage to loblolly pine seedlings as

indicated by conductivity measurements and out planting survival.

Auburn University Southern Forest Nursery Management Cooperative. Research

Report, 00-4.

Melo, A.A.M and L. C. O. Lima. 2003. Influence of three different PVC packages in the

postharvest life of loquat. Cienc. agrotec. Lavras, 27(6):1330-1339.

Meng, X., J. Han, O. Wanga and S. Tian. 2009. Changes in physiology and quality of

peach fruits treated by methyl jasmonate under low temperature stress. Food

Chemistry, 114: 1028–1035.

Minotti, G. 1988. Metals and membrane lipid damage by oxyradicals. Ann. N.Y. Acad.

Sci., 551: 34–44.

Mir, N. and R. Beaudry. 2002. Atmospheric control using oxygen and carbon dioxide:

Fruit quality and its biological basis. Sheffield academic press. UK., p. 122-156.

Mittler, R., 2002. Oxidative stress, antioxidants and stress tolerance. Trends Plant Sci.,

7:, 405–410.

Mo, K. J., and X.P. Wang. 1994. Calcium and fruit postharvest physiology. Plant

Physiology Communications, 30(1): 44–47.

Monica, I., L. Aravena, E. Scheuermann, E. Uquiche and V. Bifani. 2003. Effect of

immersion solutions on shelf-life of minimally processed lettuce. Lebensm.-Wiss.

u.-Technol., 36: 591–599.

Montavon, P., K. R. Kukic and K. Bortlik. 2007. A simple method to measure effective

catalase activities: Optimization, validation, and application in green coffee.

Anal. Biochem., 360: 207–215.

297

Montoya, M. M., J. L. Plaza and V. Lopez-Rodriguez. 1994. Relationship between

changes in electrical conductivity and ethylene production in avocado fruits.

Lebensmittel-Wissenschaft und-Technologie, 27: 482–486.

Mortazavi, N., R. Naderi, A. Khalighi, M. Babalar and H. Allizadeh. 2007. The effect of

cytokinin and calcium on cut flower quality in rose (Rosa hybrida L.) cv. Illona. J.

Food, Agric. Environ., 5 (3-4): 311 – 313.

Morton, J. F. 1987. Fruits of warm climates, Loquat. Miami, FL., p. 103–108.

Munoz, P. H., E. Almenar, M. Ocio and R. Gavara. 2006. Effect of calcium dips and

chitosan coating on post harvest life of strawberries (Fragaria ananassa), J. Post

harvest Biology and Technology, 39: 247-253.

Murata, M., M. Tsurutani, S. Hagiwara and S. Homma. 1997. Sub cellular location of

polyphenol oxidase in apples. Bioscience, Biotechnology and Biochemistry,

61:1495-1499.

Myrica, R.S. Z.G. Feng, H. Yang and Y. Li. 2005. Kinetics of relative electrical

conductivity and correlation with gas composition in modified atmosphere

packaged bayberries. LWT. , 38: 249–254.

Naczk, M. and F. Shahidi. 2004. Extraction and analysis of phenolics in food: a review.

J. Chromatography, 1054: 95-111.

Nan, S.J.S. 2007. Effects Of Pre- And Postharvest Calcium Supplementation On

Longevity Of Sunflower (Helianthus Annuus cv. Superior Sunset). (Diss). B.S.,

Louisiana State University. p.17-18.

Neill, S., R. Desikan and J. Hancock. 2002. Hydrogen peroxide signalling. Curr. Opin.

Plant Biol., 5: 388–395.

298

Nerya, O., A. Gizis, A. Zvilling, N.A. Sharabi. R. ben Ari and M. Zilberstaine. 2003.

Cold storage of loquat. Alon Hanotea, 57(6): 267-270.

Ng, T.B., W. Gao, L. Li, S.M. Niu, L. Zhao, J. Liu, L.S. Shi, M. Fu, and F. Liu. 2005.

Rose (Rosa rugosa)-flower extract increases the activities of antioxidant enzymes

and their gene expression and reduces lipid peroxidation. Biochem. Cell Biol.,

83: 78–85.

Nicolas, J., F.C. Richard, P.M. Goupy, M.J. Amiot and S.Y. Aubert.1994. Enzymatic

browning reactions in apple and apple products. Crit. Rev. Food Sci. Nutr.,

34:109-157.

Niki, E. 1987. Antioxidants in relation to lipid peroxidation. Chem. Phys. Lipids,

44: 227-253.

Niranjala, O.D.A. and A.M. Karunaratne. 2001. Response of bananas to postharvest

acid treatments. J. Hort. Sci. and Biotech., 76(1): 70-76.

Nishioka, Y., S. Yoshioka, M. Kusunose, T.L. Cui, A. Hamada, M. Ono, M.

Miyamura, S. Kyotani and T.L. Cui. 2002. Effects of extract derived from

Eriobotrya japonica on liver function improvement in rats. Biological

and Pharmaceutical Bulletin, 25(8): 1053-1057.

Noctor, G. and C.H. Foyer. 1998. Ascorbate and glutathione: Keeping active oxygen

under control. Annual Review of Plant Physiology and Plant Molecular Biology,

49: 249-279.

Oms-Oliu, G., I. O. Serrano, R. S. Fortuny, O. M. Belloso. 2008. The role of peroxidase

on the antioxidant potential of fresh-cut ‘Piel de Sapo’ melon packaged under

different modified atmospheres. Food Chemistry, 106:1085–1092.

299

Opara, E.C and S. W. Rockway. 2006. Antioxidants and Micronutrients. Dis Mon.,

52:151-163.

Ozkan, M., A. E. Kırca and B. Cemero lu. 2004. Effects of hydrogen peroxide on the

stability of ascorbic acid during storage in various fruit juices. Food Chemistry,

8(4): 591-597.

Padayatty, S.J., A. Katz, Y. Wang, P. Eck,O. Kwon, J.H. Lee, S. Chen, C. Corpe, A.

Dutta, S. K. Dutta and M. Levine. 2003. Vitamin C as an Antioxidant:

Evaluation of Its Role in Disease Prevention J. Amer. College of Nutrition,

22(1):18–35.

Padda, M.S. and D.H. Picha. 2008. Effect of low temperature storage on phenolic

composition activity of sweet potatoes. Postharvest Biology and Technology,

47:176–180.

Paliyath, G. and M.J. Droillard. 1992. The mechanisms of membrane deterioration and

dissembly during senescence. Plant physiol. Biochem., 30:789-812.

Pao, S. and P. D. Petracek . 1997. Shelf life extension of peeled oranges by citric acid

treatment. Food Microbiology, 14(5): 485-491.

Paulis, A. O. 1990. Fungal diseases of strawberry. HortiScience, 25(8): 885-888.

Pelayo, C., S.E. Ebeler and A. A. Kader. 2003. Postharvest life and flavor quality of three

strawberry cultivars kept at 5°C in air or air + 20 kPa CO2. Postharvest Biology

and Technology, 27:171–183.

Pervez, M. A., F. M. Tahir, C. M. Ayub and W. A. Cheema. 1992. physico chemical

changes in stored guava fruit as influenced by different wrapping materials. J.

Syst. and Exp. Biol., 2 (2): 31 – 37.

300

Piccioni, G.A., A.E. Watada, W.S. Conway, B.D. Whittaker and C.E. Sams. 1995.

Phospholipid, galactolipid and steryl lipid composition of apple fruit cortical

tissue following postharvest CaCl2 infiltration. Phytochemistry, 39:763-769.

Piga, A., M. Agabbio, F. Gambella and M.C. Nicoli. 2002. Retention of antioxidant

activity in minimally processed mandarin and Satsuma fruits. Lebensm. Wiss.

Technol., 35: 344–347.

Piga, A., A.D. Caro., I. Pinna and M. Agabbio. 2003. Changes in ascorbic acid,

polyphenol content and antioxidant activity in minimally processed cactus pear

fruits. Lebensm-Wiss. U-Technol., 36:257-262.

Pizzocaro, F., D.Torreggiani and G. Gilardi. 1993. Inhibition of apple polyphenoloxidase

by ascorbic acid, citric acid and sodium chloride. J. Food Process. Pres.,

17: 21–30.

Poovaiah, B.W. 1986. Role of calcium in prolonging storage life of fruits and

vegetables. Food Tech., 40: 86-89.

Poovaiah, B.W. 1988. Molecular aspects of calcium action in plants. Hortscience,

23:267-271.

Punchard, N.A. and F.J. Kelly. 1996. Free radicals: A practical approach, (n.p.)

Pyo, Y.H., T.C. Lee, L. Logendrac and R.T. Rosen. 2004. Antioxidant activity and

phenolic compounds of Swiss chard (Beta vulgaris subspecies cycla) extracts.

Food Chem., 85: 19–26.

Quiroga, M., G. Guerrero, M.A. Botella, A. Barcelo,I. Amaya, M. I. Medina, F.J. Alonso,

F.S. Milrad, H.Tigier and V. Valpuesta. 2000. A tomato peroxidase envolved in

the synthesis of lignin and suberin. Plant Physiol., 122: 1119–1127.

301

Raffo, A., I. Baiamonte, N. Nardo and F. Paoletti. 2007. Internal quality and antioxidants

content of cold-stored red sweet peppers as affected by polyethylene bag

packaging and hot water treatment. Eur Food Res. Technol., 225:395–405.

Rahaman, K. 2003. Garlic and aging: new insight into an old remedy. Ageing Res. Rev.,

2: 39–56.

Rakotonirainy, A. M., Q. Wang, and G. W. Padua. 2001. Evaluation of zein films as

modified atmosphere packaging for fresh broccoli. J. Food Sci. 66:1108-1111.

Ramassamy, C. 2006. Emerging role of polyphenolic compounds in the treatment of

neurodegenerative diseases: A review of their intracellular targets. Eur. J. Pharm.,

545:51-64.

Richardson, T. and D.B. Hyslop. 1985. Enzymes. In O. R. Fennema (Ed.), Food

Chemistry, (2nd ed.) USA: Marcel Dekker, p. 371–476.

Rind, S.Y.M. 2003. National Horticultural Seminar at NARC. PARC News, 23(1).

Rivas, N.J. and Whitaker, I.R. (1973). Purification and some properties of two

polyphenol oxidases fiom Bartlett pears. Plant Physiol., 52:501-507.

Robards, K., P.D. Prenzler, G. Tucker, P. Swatsitang and W. Glover. 1999. Phenolic

compounds and their role in oxidative processes in fruits. Food Chemistry,

66: 401–436.

Robb, D.A. 1984. Copper protein and copper enzymes.. In Contie R (ed). CRC press

Boca Raton, FL., 2: 207-241.

Robbins, R. J. 2003. Phenolic acids in foods: an overview of analytical methodology.

J. Agric. Food Chem., 51: 2886-2887.


302

Robert, C., F. Soliva and O.B. Martın. 2003. New advances in extending the shelf life of

fresh-cut fruits: a review. Trends in Food Sci. Tech., 14: 341–353.

Rocha, A.M.C.N. and A.M.M.B. De Morais. 2005. Polyphenoloxidase activity of

minimally processed ‘Jonagored’ apples (Malus domestica). Journal of Food

Processing and Preservation, 29: 8–19.

Roesler, R., G. M. Luciana, L. C. Carrasco and G. Pastore. 2006. Evaluation of the

antioxidant properties of the Brazilian Cerrado fruit Annona crassiflora

(Araticum). J. Food Sci., (71)2: 102-107.

Rojas, G.M.A., R.S. Fortuny and O. M. Belloso. 2007. Effect of Natural Antibrowning

Agents on Color and Related Enzymes in Fresh-Cut Fuji Apples as an Alternative

to the Use of Ascorbic Acid. J. Food Sci., 72(1): 36-43.

Rosen, J.C.and A.A. Kader. 1989. Postharvest physiology and quality maintenance of

sliced pear and strawberry fruits. J. Food Sci., 54, 656–659.

Roy, S., W. S. Conway, A.E. Watada, C.E. Sams, C. D. Pooley and W.P.Wergin.1994.

Distribution of the anionic sites in the cell wall of apple fruit after calcium

treatment. Protoplasma, 178: 156–167.

Rubinstein, B. 2000. Regulation of cell death in flower petals. Plant Mol. Biol.,

44:303-318.

Rueda, F.D.N. 2005. Guava (Psidium guajava l.) fruit phytochemicals, antioxidant

properties and overall quality as influenced by postharvest treatments. M.Sc.

Dissertation. The Graduate School of The University of Florida.

Ruoyi, K., Y. Zhifang and L.Z. Zhaoxin. 2005. Effect of coating and intermittent

warming on enzymes, soluble pectin substances and ascorbic acid of Prunus

303

persica (cv. Zhonghuashoutao) during refrigerated storage. Food Research

International, 38: 331–336.

Sakuramata, Y. H. Oe, S. Kusano, and O. Aki. 2004. Effects of combination of

CaiapoReg. with other plant-derived substance on anti-diabetic efficacy in KK-Ay

mice. Bio Factors, 22 (1/4): 149-152.

Sala, J. M. and M. T. Lafuente. 2004. Antioxidant enzymes activities and rind staining in

‘Navelina’ oranges as affected by storage relative humidity and ethylene

conditioning. Postharvest Biology and Technology, 31: 277–285.

Saliba, W.R., L.H. Goldstein, G.S. Habib and M.S. Elias. 2004. Toxic myopathy induced

by the ingestion of loquat leaf extract. Annals of the Rheumatic Diseases,

63:1355-1356.

Salviet, M.E.. 1997. A summary of CA and MA recommendations for harvested

vegetables. In: Salviet M.E. (ed.), Proceedings Seventh International Controlled

Atmosphere Research Conference, Vol. 4.

Sams, C.E. 1999. Pre-harvest factors affecting postharvest texture. Postharvest Bio.

Tech. 15:249-254.

Sanchez, A.A. and F. Solano. 1997. A pluripotent polyphenol oxidase from the

melanogenic marine alteromonas shares catalytic capabilities. Biochem. Biophys.

Res .Comm., 240: 787-792.

Sanchez, M.C., M. Camara and C. Dıez-Marques. 2003. Extending shelf-life and

nutritive value of green beans (Phaseolus vulgaris L.) by controlled atmosphere

storage: macronutrients. Food Chemistry, 80: 309–315.


304

Santerre, C. R., J.N. Cash, and D.J. Vannorman. 1988. Ascorbic acid/citric acid

combination in the processing of frozen apple slices. J. Food Sci., 53: 1713–1716.

Saper, G.M. 1993. Browning of foods: control by sulphites, antioxidants and other

means. Food Technology, 47(10):75-84.

Sardi, 2005. www.sardi.sa.gov.au/pages/horticulture/citrus/hort_citp_poststorage.htm.

Scandalios, J.G. 1993a. Oxygen stress and superoxide dismutase. Plant Physiol.,

101:1-15.

Scandalios, J.G., 1993b. Regulation and properties of plant catalases. In: C. Foyer and P

Mullineaux (Editors), Photooxidative Stress in Plants. CRC Press, Boca Raton,

Fla., p. 275-315.

Schoellhorn, R., E. Emino, and E. Alvarez. 2003. Specialty Cut Flower Production

Guides for Florida: Sunflower. Environ. Hort. Department, FL. Coop. Ext. Serv..

Institute of Food and Agricultural Sciences, Univ of Florida, p.1-3.

Setha, S., S. Kanlayanarat and V. Srilaong. 2000. Changes in Polyamine levels and

peroxidase activity in “Khakdun” papaya (Carica papaya L.) under low

temperature storage conditions. In: Quality Assurance in Agricultural Produce,

Ed. G. I. Johnson, LeVan To, N. D. Duc, M. C. Webb. ACCIAR Proceedings,

100: 593–598.

Severini, C., A. Baiano, T. De Pilli, R. Romaniello and A. Derossi. 2003. Prevention of

enzymatic browning in sliced potatoes by blanching in boiling saline solutions.

Lebensm.-Wiss. u.-Technol., 36:657–665.

Shear, C.B. 1975. Calcium nutrition and quality in fruit crops. Commun. Soil Sci.

Plant Anal. 6:233-244.


305

Shewfelt, R. L. 1986. Postharvest treatment for extending the shelf-life of fruits and

vegetables. Food Technol., 40:70-79.

Shewfelt, R. 1990. Sources of variation in the nutrient content of agricultural

commodities from the farm to the consumer. J. Food Quality, 13: 37-54.

Shewfelt, R. L. 1994. Quality characteristics of fruits and vegetables. In: Singh, P. and F.

Oliveira.(eds.). Minimal processing of foods and process optimization. An

interface, CRC Press Inc., p. 437 - 457..

Shewfelt, R. L. and A.C. Purvis. 1995. Toward a comprehensive model for lipid

peroxidation in plant storage disorders. HortScience, 30: 213–217.

Shui, G. and L. P. Leong. 2002. Separation and determination of organic acids and

phenolic compounds in fruit juices and drinks by HPLC. J. Chromatography,

977(1): 89–96.

Shuiliang, C., Y. Zhende, L. Laiye, L. MeiXue, S.L.Chen, Z.D. Yang, J.Y. Lai and M.X.

Liu. 2002. Studies on freshness keeping technologies of loquat. South China

Fruits, 31(5): 28-30.

Siddiqui, S. and O.P.Gupta. 1995. Effect of post-harvest application of some chemicals

on the shelf life of ber (Ziziphus mauritiana Lamk.) fruits. Haryana J.of Hort.

Sci., 24(1): 19-23.

Singleton, A.G.L. 2003. Influence of thermal postharvest stress on mango (Magnifera

Indica) polyphenolics during ripening. M.Sc. Dissertation. Univ. of Florida: 6 pp.

Slinkard, K. and V.L. Singleton. 1977. Total phenol analysis: automation and comparison

with manual methods. Amer. J. Enol. Vitic., 28: 49-55.


306

Smilanick, J. L., D.A. Margosan, F. Mlikota, J. Usall and I.F. Michael.1999. Control of

citrus green mold by carbonate and bicarbonate salts and the influence of

commercial post harvest practices on their efficacy. Plant Disease, 83: 139 - 145.

Smirnoff, N. 2000. Ascorbic acid: metabolism and functions of a multifaceted molecule.

Currnet opinion in plant biology, 3:229-235

Soliva, F., R. C. Oms, G. Oliu, G.B. Martın and O. Belloso. 2002. Effects of ripeness

stages on the storage atmosphere, color, and textural properties of minimally

processed apple slices. J. Food Sci., 67: 1958–1963.

Soliva, R. F. and O.B. Martin. 2006. Effect of modified atmosphere packaging on the

quality ofd fresh cut fruits. Stewert post harvest review, 1:3 pp

Son, S. M., K.D. Moon and C. Y. Lee. 2001. Inhibitory effects of various antibrowning

agents on apple slices. Food Chemistry, 73: 23–30.

Sonia, Z. V. and A. R. Chaves. 2006. Antioxidant responses in minimally processed

celery during refrigerated storage. Food Chemistry, 94: 68–74.

Spychalla, J. P. and S.L. Desborough. 1990. Superoxide dismutase, catalase, and

a-tocopherol content of stored potato tubers. Plant Physiol., 9: 1214-1218.

Srilaong, V. and Y. Tatsumi. 2003. Changes in respiratory and antioxidative parameters

in cucumber fruit (Cucumis sativus L.) stored under high and low oxygen

concentrations. J. Jpn. Soc. Hort. Sci., 72: 525–532.

Steel, R.G.D., Torrie, J.H., and D. A. Dickey. 1997. Princip/es and Procedures of Statistics:

A Biometrical Approach. 3rd ed. New York: The McGraw-Hill Companies, Inc.

307

Stegmann, H. B., P. Schuler, H.J. Ruff, M. Knollmuller and W. Loreth. 1991. Ascorbic

acid as an indicator of damage to forest. A correlation with air quality. Zeitschrift

fu¨ r Naturforschung, 46: 67–70.

Sugumaran, M. 1988. Molecular mechanisms for cuticular sclerotization. Adv. Insect

Physiol., 2(1): 179-231.

Suutarinen, M. 2002. Effects of prefreezing treatments on the structure of strawberries

and jams. VTT Biotechnology. Technical Research Centre of Finland,

Vuorimiehentie 5, P.O. Box 2000, Finland, 28 pp.

Takuma, D., J. Yokota, A. Hamada, S. Yoshioka, M. Kusunose, M. Miyamura, S.

Kyotani, and Y. Nishioka. 2005. Effects of Eriobotrya japonica seed extract in a

model rat of lipopolysaccharide-induced inflammation. J. Japanese Soc. for Food

Sci. and Tech., 52(2): 88-93.

Technol., 48:106–10.

Talasila, P., K. Chau and J. Brecht. 1995. Design of rigid modified atmosphere packages

for fresh fruits and vegetables. J. Food Sci., 60: 758 – 769.

Thompsom, J.E. 1988. The molecular basis for membrane deterioration during

senescence, p 51-83, In: L.D. Nooden, A.C. Leopold (eds). Senescence and Aging

in Plants. Academic Press, New York.

Thompson, J.E., R.L. Leggee and R.F. Barber. 1987. The role of free radicals in

senescence and wounding. New Phytologist, 105:317-344.

Thorp, T. G., I.B. Ferguson, L.M. Boyd and A.M. Barnett. 2003. Fruiting position,

mineral concentration and incidence of physiological pitting in ’Hayward’

kiwifruit. J. Hort. Sci. and Biotech., 78: 505–511.

308

Tian, S.P. A.L. Jiang, Y. Xu and Y.S. Wang. 2004. Responses of physiology and quality

of sweet cherry fruit to different atmospheres in storage. Food Chemistry,

87: 43–49.

Tian, S.P., B. Li and Y. Xu. 2005. Effects of O2 and CO2 concentrations on physiology

and quality of litchi fruit in storage. Food Chemistry, 91: 659–663.

Tian, S., B. Li and Z. Ding. 2007. Physiological Properties and Storage Technologies of

Loquat Fruit. Fresh Produce, 1(1): 76-81.

Tierra, M. 2005. Loquat Leaf, fruit and seed. w.ww.planetherbs.com/articles/loquat

_leaf.htm. searched on 17-06-05.

Toit, R.D., Volsteedt, Y. and Z. Apostolides. 2001. Comparison of the antioxidant

content of fruits, vegetables and teas measured as vitamin C equivalents.

Toxicology, 166: 63–69.

Toivonen, P.M.A. 2003. Postharvest treatments to control oxidative stress in fruits and

vegetables: Postharvest oxidative stress in horticultural crops. Foods products

press. The Howerth press. Binghampton. N.Y., p. 225-246.

Toor, R.K. and G. P. Savage. 2006. Changes in major antioxidant components of

tomatoes during post-harvest storage. Food Chemistry, 99: 724–727.

Torre, S., A. Borochov, and A.H. Halevy. 1999. Calcium regulation of senescence in rose

petals. Physiol. Plant., 107:214-219.

Tsuchihashi, H., M. Kigoshi, M. Iwatsuku and E. Niki. 1995. Action of ß-carotene as an

antioxidant against lipid peroxidation. Arch. Biochem. Biophys., 323: 137-147.

Ulrich, R. 1970. Organic acids. In: Hulme, A.C. (Ed.), The Biochemistry of Fruits and

Their Products, vol. 1. Academic Press, New York, p. 89–118.

309

Vamos-Vigyazo, L. 1981. Polyphenol oxidase and peroxidase in fruits and vegetables.

Crit. Rev. Food Sci. Nutr., 9: 49–127.

Vamos-Vigyazo, L. 1995. Prevention of enzymatic browning in fruits and vegetables. In:

Enzymatic Browning and its Prevention, C.Y. Lee and JR. Whitaker (Eds.), ACS

Symp. Ser. 600, Washington, DC., p. 49-62.

Vela, G., D.M. Leon, H.S. Garcia and J.D. C. Unida. 2003. Polyphenoloxidase activity

during ripening and chilling stress in ‘Manila’ mangoes. J. Hort. Sci. Biotechnol.,

78: 104-107.

Veltman, R.H., R. M. Kho, A. C. R. van Schaik, M. G. Sanders and J. Oosterhaven.

2000. Ascorbic acid and tissue browning in pears (Pyrus communis L. cvs Rocha

and Conference) under controlled atmosphere conditions. Postharvest Biology

and Technology,19(2): 129-137.

Verlangieri, A.J., J. C. Kapeghian, S. El-Dean and M. Bush. 1985. Fruit and vegetable

consumption and cardiovascular mortality. Med. Hypoth., 16:7-15.

Verlinden, B.E. and B.M. Nicolai. 2000. Fresh-cut fruits and vegetables. Acta Hort.,

518: 223–230.

Vina, S and A. Chaves. 2003. Textural changes in fresh cut celery during refrigerated

storage. J.Sci. Food Agri., 83: 1308 - 1314.

Vincenzo, L.L., S. Vito, F. C. Palmieri and V. Sumere . 1989. The beneficial effect of

citric and ascorbic acid on the phenolic browning reaction in stored artichoke

(Cynara scolymus L.) heads. Food Chemistry, 33(2): 93-106.

Voet, D. and J.G. Voet. 1990. Biochemistry. Wiley, New York, 284 pp.

310

Walker, J.R.L. 1995. Enzymatic browning in fruits: Its biochemistry and control. In

Enzymatic Browning and its Prevention, C.Y. Lee and J.R. Whitaker (Eds.), ACS

Symp. Ser. 600, Washington, DC., p. 8-22.

Wang , C.Y. 1995. Effect of temperature preconditioning on catalase, peroxidase, and

superoxide dismutase in chilled zucchini squash. Postharvest Biology and

Technology, 5:67-76.

Wang, Y.S., S.P. Tian and Y. Xu. 2005. Effects of high oxygen concentration on pro-

and anti-oxidant enzymes in peach fruits during post harvest periods. Food

Chemistry, 91: 99–104.

Watada, A. E. 1987. Vitamins. In: J. Weichmann (Ed.), Postharvest physiology of

vegetables. New York: Dekker, p.12-19.

Watada, A. E., and L. Qi. 1999. Quality of fresh-cut produce. Postharvest Biology and

Technology, 15: 201–205.

Watkins, C.B. 2000. Responses of horticultural commodities to high carbon dioxide as

related to modified atmosphere packaging. Hort Technology, 10:501-506.

Watkin, C.B. and M.V. Rao. 2003. Genetic variation and prospects for genetic

engineering of horticultural crops for resistance to oxidative stress induced by

postharvest conditions: Postharvest oxidative stress in horticultural crops. Foods

products press. The Howerth press. Binghampton. N.Y., 209 pp.

Wee, Y.C. and K. Hsuan. 1992. An illustrated dictionary of Chinese Medicinal Herbs.

GRC5 Pub. Box 1460, Sebastopol, CA.

311

Weller, A., C.A. Sims, R. F. Matthews , R. P. Bates and J. K. Brecht. 1997. Browning

susceptibility and changes in composition during storage of carambola slices. J

Food Sci., 62:256-60.

Whitaker, B.D., J.D. Klien, W.S.Conway and C.E.Sams. 1997. Influence of pre storage

heat and calcium treatments on lipid metabolism of ‘Golden Delicious’ apples.

Phytochemistry, 45:465-472.

White, P. J. and M.R. Broadley. 2003. Calcium in plants. Ann. Bot., 92: 487–511.

Whitlow, T. H., N.L. Bassuk, T.G. Ranney and D.L. Reichert. 1992. An improved

method for using electrolyte leakage to assess membrane competence in plant

tissues. Plant Physiology, 98: 198-205.

Willet, C.M. 1994. Micronutrients and cancer risk. Amer. J. Clin. Nutr., 59:162-165.

Wills, R., T. Lee, D. Graham, W. McGlasson, and G. Hall. 1982. Postharvest. An

introduction to the Physiology and Handling of Fruit and Vegetable, The AVI

Publishing Company Inc. Westport, Conn., 166 pp.

Witkop, C.R. Jr. 1985. Inhered disorders of pigmentation. In Genodermatoses: Clinics in

Dermatology, R.M. Goodman and J.M. Lippincott (Eds.), Philadelphia, PA.,

p. 70-134.

Xi, Y. F., Y.H. Zheng, T.J. Ying, J.F. Ying and Z.L. Chen. 1994. The physiological

senescing of the postharvest bayberries. Acta Horticulturae Sinica,

21(3): 213–216.

Xu, J. 2005. The effect of low-temperature storage on the activity of polyphenol oxidase

in Castanea henryi chestnuts. Postharvest Biology and Technology, 38: 91–98.

312

Xuetong, F. and J.B.S. Kimberly. 2005. Assessment of radiation sensitivity of fresh-cut

vegetables using electrolyte leakage measurement. Postharvest Biology and

Technology, 36(2):191-197.

Yamaguchi, F., Y. Yoshimura, H. Nakazawa and A. Ariga. 1999. Free radical scavenging

activity of grape seed extract and antioxidants by electron spin resonance

spectrometry in an H2O2/NaOH/DMSO system. J. Agri. and Food Che.,

47(7): 2544–2548.

Yamashita, F., L.H.D. Miglioranza, L.D. Miranda, C.M.D. Souza. 2002. Effects of

packaging and temperature on postharvest of atemoya. Rev. Bras. Frutic.,

Jaboticabal, (24)3: 658-660.

Yelena G., Sheptovitsky, and G.W. Brudvig. 1996. Isolation and characterization of

spinach photo system II membrane-associated catalase and polyphenol oxidase.

Biochemistry, 35: 16255-16263.

Young, J. 2002. Field Grown Cut Flower Production in Southern Louisiana. M.Sc.

Thesis. Louisiana State University. Baton Rouge, LA.

Zagham, M. 2003. Effect of pre-harvest factors and different storage conditions on yields

and postharvest longevity of green coriander (Coriandrum sativum L.) M.Sc.

Hons.) Hort. Diss. Univ. of Arid Agri., Rawalpindi, Pakistan.

Zagory, D and K.K. Kader. 1988. Modified atmosphere packaging of fresh produce.

Food Technology, Chicago, 42: p.70-77.

Zawistoski, F., C.G. Biliaderis and N.A.M. Eskin. 1991. Polyphenol oxidase. In

Oxidative Enzymes in Food, D.S. Robinson and N.A.M. Eskin (Eds.), Elsevier,

New York, NY., p. 217-273.

313

Zhang, L., H. Wang, L.K. Gong, X.H. Li, Y. Cai, X.M. Qi, L.L. Liu, Y.Z. Liu, X.F. Wu,

F.P. Chen, C.G. Huang and J. Ren. 2004. Feitai attenuates bleomycin-induced

pulmonary fibrosis in rats. Biological and Pharmaceutical Bulletin,

27 (5): 634-640.

Zhang, Y.L. and R. P. Zhang. 2008. Study on the Mechanism of Browning of

Pomegranate (Punica granafum L. cv. Ganesh) Peel in Different Storage

Conditions. Agricultural Sciences in China. 7(1): 65-73.

Zheng, Y. H. and Y.F. Xi. 1999. A study on the relationship between the changes of

postharvest membrane permeability, respiration rate, ethylene production and the

storability of loquat fruit. J. Jiangxi Agric. Univ., 21: 81–82 (in Chinese; English

abstract).

Zheng, Y. H., S. X. Guo, L. Q. Jiu, L. S. Yu and X. Y. Fang. 2000a. Effect of high

oxygen respiration rate, polyphenol oxidase activity and quality in postharvest

loquat fruits. Plant. Physiol. Communications, 34(4):318-320.

Zheng, Y. H., S.Y. Li and Y. F. Xi. 2000b. Changes of cell wall substances in relation to

flesh woodiness in cold stored loquat fruits. Acta Phytophysiol. Sin., 26: 306–310

(in Chinese; English abstract).

Zheng, S.Q., J.M. Jiang, Z.H. Zhang, X.P. Chen, J.H. Xu and Y.J. Liu. 2001. Fujian J.

Agric. Sci., 16(3): 45-47.

Zhuang, H., M.M. Berth and D.F. Hildebrand. 1994. Packaging influences total

chlorophyll, soluble protein, fatty acids composition and lipoxygenase activity in

broccoli florets. J. Food Sci., 59: 1171-1174.

relationship of antioxidants with qualitative changes in local cultivars of loquat...

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