MINIMAL PROCESSING OF HONEY POMELO (CITRUS GRANnIS (L.) OSBECK)

Sabrina Anak. Lawrence Anyau

58 360

Bachelo (Plant Reso

f Science with Honours Science and Management)

Sl18 2006 2006

MINIMAL PROCESSING OF HONEY paMELa (CITRUS GRANDIS (L.) OSBECK)

SABRINA ANAK LAWRENCE ANYAU

This report is submitted in partially fulfillment of the requirements for the degree of

Bachelor of Science with Honours

(Plant Resource Science and Management)

Faculty of Resource Science and Technology

UNIVERSITY MALAYSIA SARA WAK

2006

ACKNOWLEDGEMENT

Behind the development of this project, I would like to express my heartfelt gratitude to

my supervisor, Associate Professor Dr Sim Soon Liang and co-supervisor, Dr Petrus

Bulan for their endless guidance, kind support and comments throughout my final year

project.

Special thanks to Mr. Lau Cheng Yuon, Senior Research Officer of Agricultural Research

Centre, Semongok for providing the guidance, resources and facilities for this study.

Word of appreciation goes to Dr Lily Eng, Senior Research Officer of Agricultural

Research Centre, Mr. Jeffrey, Mr. Julin, Madam Christina Ong, lab assistants and other

supporting staffs for their kind assistance offered during the period when my final year

project was carried out.

I also would like to express my gratitude to Associate Professor Dr Sepiah Muid for her

teaching and guidance throughout the completion of this project. Warmest thanks to

Miss Rebecca Edward for her guidance, to my family, all my friends and those who have

given me supports and companionship towards the improvement and completion of this

final year project.

Pusat Khidmat MaklUmat Akadenup. UNIVERSITI MALAYSIA SARAWA¥

94100 KOla Samarahan

./

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENT

T ABLE OF CONTENT ii

LIST OF PLATES iii

LIST OF FIGURES iv

LIST OF TABLES v

ABSTRACT vi

ABSTRAK vii

CHAPTER 1 INTRODUCTION 1

CHAPTER 2 LITERATURE REVIEW 5

CHAPTER 3 MATERIAL AND METHODS 9

3.1 Material 9

3.2 Methods 9

3.2.1 Peeling Process 11

3.2.2 Effect of storage temperatures on quality of peeled honey

pomelo 16

3.2.2.1 Experiments

3.2.2.2 Quality assessment

3.2.2.3 Disease identification

3.2.2.4 Statistical Analysis

3.2.2.5 Storage Room

ii

j

I

CHAPTER 4

CHAPTER 5

Refrences

Appendices

PLATE

RESULTS AND DISCUSSION 19

CONCLUSION AND RECOMMENDATION 46

48

52

LIST OF PLATES

Page

1.1 Fruit of honey pomelo 3

1.2 Tree of honey pomelo 3

1.3 Ed ible segments of honey pomelo fruits 3

1.4 Different size and shape of honey pomelo 4

3.1 Size of honey pomelo chosen 10

3.2 Chiller room for storage before processing 10

3.3 Inside the chiller room 10

3.4 Honey pomelo after taken out from the chiller room 12

3.5 Surface strelization 12

3.6 Dipping the knives in 150ppm chlorinated water 13

3.7 Placing honey pomelo into fruit baskets after washing 13

3.8 Air-drying 13

3.9 Peeling 14

3.10 Peeling process continued 14

3. 11 Covered syainless steel bench 14

iii

3.1 2

3.t3

3.14

3.15

3.16

3.17

Water absorbent tissue

Clean honey pomelo flesh placed in plastic container

Packed flesh of honey pomelo

Samples to stored

Laboratory room

Ambient sample spoiled at day 8

15

15

15

16

18

19

LIST OF FIGURES

FIGURE

Changes in pH of minimally processed honey pomelo

stored at different temperatures from day 0 to day 12

Page

27

2 Changes in Brix (%) of minimally processed honey pomelo

stored at different temperatures from day 0 to day 12 33

3 Changes in total soluble solids (g/IOOml) of minimally processed

honey pomelo stored at different temperatures from day 0

to day 12 35

4 Changes in pH of minimally processed honey pomelo

stored at different temperatures from day 0 to day 12 38

5 Changes in vitamin C (mg/IOOml) of minimally processed

honey pomelo stored at different temperatures from day 0 to day 12 41

iv

I

,.. r

LIST OF TABLES

TABLE

Mean ofBrix (%) of honey pomelo at different temperatures

after 3 and 6 days in storage

2 Mean ofBrix (%) of honey pomelo at different temperature

stored at day 8 and day 12

3 Analysis of variance for Brix (%) of honey pomelo at different

temperature stored at day 8 and 12

4 Mean of Total Soluble Solids (gIlOOml) of honey pomelo at

different temperatures after 3 and 6 days in storage

5 Mean ofTotal Soluble Solids (gIlOOml) of honey pomelo at

different temperature stored at day 8 and day 12

6 Analysis of variance for Total Soluble Solids (gllOOml)

of honey pomelo at different temperature stored at day 8 and 12

7 Mean of pH of honey pomelo at different temperatures after 3

and 6 days in storage

8 Mean of pH of honey pomelo at different temperatures stored

at day 8 and day 12

v

Page

21

22

22

23

24

24

25

26

9 Analysis of variance for pH of honey pomelo at different temperature

stored at day 8 and day 12 26

10 Mean of acidity (%) of honey pomelo at different

after 3 and 6 days in storage

temperatures

28

11 Mean of pH of honey pomelo at different temperatures stored

at day 8 and day 12 29

12 Analysis of variance for acidity (%) of honey pomelo at

different temperature stored at day 8 and day 12 29

13 Mean of Vitamin C (mgll OOml) of honey pomelo at

different temperatures after3 and 6 days in storage 30

14 Mean of Vitamin C (mg/lOOml) of honey pomelo at different

temperatures stored at day 8 and day 12 31

15 Analysis of variance for Vitamin C (mg/IOOml) of honey pomelo

at different temperature stored at day 8 and day 12 31

16 Mean of Brix (%) of honey pomelo at different

after 8 days in storage

temperatures

32

17 Analysis of variance for Brix (%) of honey pomelo stored

at different temperature after 8 days in storage 33

18 Mean of Total Soluble Solids (g/lOOml) of honey pomelo

at different temperatures after 8 days days in storage 34

19 Analysis of variance for Total Soluble Solids (g/lOOml) of honey

pomelo stored at different temperature after 8 days in storage 35

20 Mean of pH of honey pomelo at different temperatures after 8 days In

storage 36

21 Analysis of variance for pH of honey pomelo stored at different

temperature after 8 days in storage 37

22 Mean of acidity (%) of honey pomelo at different temperatures

after 8 days in storage 39

23 Analysis of variance for acidity (%) of honey pomelo stored at

different temperature and number of days in storage 39

24 Mean of Vitamin C (mg/l00ml) of honey pomelo at different

temperatures after number of days in storage 40

25 Analysis of variance table for Vitamin C (mg/l00ml) of honey pomelo

stored at different temperature and number of days in storage 40

j

,.

Minimal Processing of Honey Pomelo (Citrus grandis I L.] Osbeck)

Sabrina ar.ak Lawrence Anyau

Plant Resource Science and Management Programme Faculty of Resource Science and Technology

University Malaysia Sarawak

ABSTRACT

Minimal processing of honey pomelo was carried out. The fruits were peeled and the segments make up

with edible juice sacs were placed in a plastic container (polypropylene container) and the samples were

stored at three temperatures i.e 5°C, 10°C and ambient. In the first experiment, samples were analyzed for

Brix, pH, total soluble solids, acidity and vitamin C at day 0, 3, 6, 8 and 12. In the second experiment, the

samples were analyzed for the same parameters at day 0, 2, 4, 6 and 8. Statistical analysis of the first

experiment showed that storage temperatures did not affect quality parameters for up to 6 days

significantly. After 8 days or longer, changes in quality parameters due to storage temperatures were

significant. In the second experiment, quality parameters of minimally processed honey pomelo did not

change significantly when stored at 5°C, 10°C for 8 days in storage. Result of this study showed that

minimally processed honey pomelo can last for up to 8 days or longer when stored at 5°C and 10°C. The

ambient samples could only be stored for not more than 6 days.

Key words: Minimal processing, honey pomelo, post harvest

v

I

ABSTRAK

Pemprosesan minimum buah Limau Madu lelah dUalankan. . Buah yang lelah dikupas disimpan di dalam

kOlainer pla~tik (propylene kontainer). Kesemua sampel kemudiannya disimpan di dalam suhu yang

berlainan iailu 5°C, 10"C dan pada suhu persekilaran. Dalam eksperimen perlama, analisis sampel lelah

dijalankan untuk Brix, pH, kandungan pejal larul (TSS), keasidan dan vitamin C pada hari 0, 3, 6, 8 dan

12. Unluk eksperimen kedua, analisis yang sama lelah dijalankan pada hari 0, 2,4.6 dan 8. Analisis

slatislik menunjukkan. tiada perubahan pada Brix, pH, kandungan pejallarut (TSS). keasidan dan vitamin

C apabi/a buah disimpan pada suhu yang berbeza pada hari 0 hingga hari keenam. Terdapat perubahan

pada parameler lersebut apabi/a disimpan di dalam suhu yang berbeza iailu pada 8 hari hingga 12.

Eksperimen yang kedua pula menunjukkan tiada perubahan pada parameter apabila disimpan di dalam

suhu yang berbeza iaitu, 5°C dan 10 fJC selama 8 hari dalam penyimpanan .. Didapati Iimau madu yang

lelah diproses dapat disimpan selama 8 hari atau lebih apabi/a disimpan di dalam suhu 5"C dan lOT.

Manakala limau madu yang disimpan pada suhu persekitaran dapal disimpan tidak lebih dari 6 hari.

Kala kunci : Pemprosesan minimum, Limau Madu. lepas tuai

vi

,.....

CHAPTER 1

INTRODUCTION

Pomelo or shaddock belongs to the family Rutaceae. The name shaddock arose after a

captain named Shaddock brought this fruit to the Caribbean. Its scientific name is Citrus

grandis (L.) Osbeck. It is a native from Southern China or the Malaysia and Indian

archipelagos (Davies and Albrigo, 1994). Pomelo is known as 'Limau Bali','Limau

Abong' or 'Limau Besar' by the locals.

The tree of pomelo is evergreen and the height is approximately 10 metres (Chin and

Y ong, 1980). The size of leaves, flowers and fruits are the largest of any citrus species

(Davies and Albrigo, 1994). However, the basic structure of flower is the same as other

citrus. The shape of the fruit ranges from ovalish to slightly rounded. The fruit diameter

ranges from 10 to 30 cm. The rough peri carp which is commonly called as the skin is

light green to yellowish in color. The inner part of the peri carp is white to pinkish in

color and it is thick and spongy. The thickness of the pericarp ranges from 0.6 to 2.5 cm

across.

The fruit consists of 10 to 15 segments. The edible part of pomelo is the small, oval­

shape and crystal-like juice sacs. These juice sacs are covered by a white membranous

structure to form segments of edible part. This white membranous structure is not

latable and is removed before eating. The seeds of pomelo are large and plump.

l

When the fruit is matured, the color of the pericarp changes from dark green to light

yellowish green. Pomelo is a popular fruit in China and Southeast Asia (Davies and

Albrigo, 1994).

In today's Living, people are looking for ready-to-eat products. The demand for ready-to­

eat or pre-peeled fruits is rapidly increasing. The demand increases not only in

traditional market but also in fast food, food services and food processors (Vinning,

1995). Modern people prefer ready-to-eat or pre-peeled fruit because it is more

convenience and time saving. It is particular suitable for tourists.

Honey pomelo (Plate 1.1 and 1.2) is a suitable fruit for preparation of pre-peeled fruit

because of its unique characteristics. It is easy to peel and to separate the fruit segments.

Furthermore, the edible portion can be hygienically taken out from the membranous

structure (Plate 1.3). The flesh color is white or almost crystal clear. It has sweet juicy

taste with slightly sour. The size of honey pomel0 varies from small to medium and the

shape ranges from ovalish to almost rounded (Plate 1.4).

Minimally processed fruit is a product resulted from the new trend in fruit consumption.

In the case of honey pomelo, hygienically pre-peeled fruits (the edible segments

consisting of juice sacs) are packed in small suitable packages and stored at low

temperature before distribution. The purpose of minimal processing is to provide fresh

peeled fruits with an extended shelf-life while maintaining the quality and the freshness

2

of the fruits (Latifah et ai., 2002). This trend of fruit processing also spreads to other

ASEAN countries including Singapore and Brunei (Mohd Salleh et ai., 1999).

The objective of this project is to develop an appropriate protocol for minimal processing

of honey pomelo.

Plate 1.1 Fruit of honey pomelo (Source: Kabuloh Agricultural Station)

Plate 1.2 Tree of honey pomelo (Source: Kabuloh Agricultural Station)

3

Plate 1.3 Edible segments of honey pomelo which had been taken out cleanly

Plate 1.4 Different size and shape of honey pomelo fruit

4

CHAPTER 2

LITERA TURE REVIEW

Minimal processing is a new method of fruit processing brought about by the new trend

in fruit consumption which has been spread to other Asia countries such as Singapore,

Thailand and Brunei. This new trend of fruit consumption offers several advantages. It

reduces preparation time, extends shelf-life, minimizes quarantine barriers in some

importing countries and also space saving in packaging and transportation (Reyes, 1997).

However, minimal processing has some disadvantages. Minimally processed fruits are

easily spoiled due to injuries during cutting. The minimally processed fruits are very

perishable and vulnerable because the fruit tissue is still living (Latifah et aI. , 2002).

Factors such as physiological ageing and biochemical changes can lead to deterioration of

minimally processed produce (Ahvenainen, 1996). The Malaysian Agricultural Research

and Development Institute (MARDI) had carried out minimal processing on many

tropical fru its such as mango, pineapple, jackfruit and durian.

The most important factor in minimal processing operation is to handle the process under

hygienic condition to avoid contamination of the cut-surface. This is because minimally

processed produce if injured, spoils faster than the whole fruits. It is important to ensure

minimally processed fruits or vegetables are safe for consumption (Faridah et at., 1999).

Fruits such as pineapple, papaya, mango and watennelon are peeled and cut or sliced into

small sizes or specific cutting style (Mohd Salleh et at., 1999).

5

Chokanan mango, a cultivar of mango which has been introduced from Thailand is the

most popular type of mango in Malaysia and given credits for its sweet juicy taste

(Ahmad et ai., 1999). The skin which is easy to peel makes it suitable for minimal

processing. Before processing, the fruit was thoroughly clean with sterilized water after

harvesting. The fruit was immediately peeled with sharp knife without injuring the flesh.

The peeling and the slicing process were done hygienically to provide safe products.

Minimally processed mango can exhibit shelf-life for two to three weeks when packed in

ethylene scavenging films. The minimally processed Chokanan mango can be stored at

2°C to maintain the freshness.

Minimally processed jackfruit (Artocarpus heterophyllus Lank.) exhibits shelf-life for

three weeks. The fruit is suitable for minimal processing because the flesh can be taken

out cleanly from the thick pulp. Hygienic condition was observed during handling of the

fruits to avoid any contamination. Minimally processed jackfruit was effectively packed

in propylene containers and thermal freezing packing for storage, transportation and

market display (Anon, undated). The lower temperature which was attained in the

thermal freeze packing, reduced weight loss and maintained the freshness, aroma, texture

and chemical compositions. Minimally processed jackfruit can be stored for 2 days at

25°C, 6 days at lOOC and 3 weeks at 2°C (Latifah et al., 2000a).

Durian (Durio zibethinus Murr.) is suitable for minimal processing. The difficulty in

peeling due to the hard husk and sharp spines are the reasons why durian is suitable for

minimal processing. The peeling can be done easily by using specialized tool

6

(Booncherm and Siripanich, 1991). Though it has spiny skin, the flesh inside is arranged

orderly and cleanly. The flesh can be taken out cleanly without damaging the flesh.

Thermo freezing technique was used for minimal processing of durian by flowing

nitrogen liquid at low temperature which is <-SO °C while the pressure was stabilized.

After freezing, the flesh was place<l in the freezer when the temperature reached to -I SoC.

The temperature was maintained at <-I SoC to maintain the quality. The flesh can be

taken out to thaw at room temperature before eating (Anon., 2005).

For minimal processing of pineapple (Ananas comosus (L.) Murr), the ripened fruits were

washed thoroughly to remove dirt and stain. The fruits were soaked in chlorinated water

for to minutes to kill fungus and molds. Most of the fruits for minimal processing were

soaked in 100 ppm chlorinated water for 10 minutes (Faridah et aI., 1999). After air

drying, the pineapple skin was peeled. Then, each of the fruit was sliced longitudinally

into 8 portions and packed into polypropylene containers. The containers were placed in

insulated boxes and then stored at 2°C to make sure that the temperature of sliced

pineapples attained at 2°C. The minimally processed pineapples can be stored for 2 days

and 7 days at temperature of 25°C and 10°C respectively (Latifah et al., 2000b).

In minimal processing of orange, the cut fruits were stored at 4°C. At first S days of

storage, most of the major quality parameters were almost unchanged except for titratable

acidity which was decreasing around 36% and ascorbic acid decreased approximately

22%. Meanwhile for pH, it did not change dramatically in 10 days of storage at 4°C

.87±O.07). At 25°C, the minimally processed orange exhibit shelf-life for only 2 days.

7

Meanwhile at 4°C low pH coupled with low temperature could extend the shelf-life of

fresh cut orange to 15 days. However, the shelf-life for sensory analysis of the fresh cut

oranges was limited to 5 days of storage at 4°C (Rocha et al., 1995).

Papaya or Carica papaya L. is one of the popular fresh-cut fruits served in restaurants.

Before processing, the fruits were dipped in 200 to 300 ppm of chlorinated water to

sterilize the fruits. Then, the fruits were peeled, deseeded and cut into small pieces. The

cut fruits were wrapped using cling-wrap (Siripanich, 1993). The minimally processed

papaya can be stored at 1°C in modified atmosphere packaging for 16 weeks. The long

storage is achieved when the sliced papaya weighing about 10 to 25g are dipped in 5% of

citric acid solution and aired with 15 to 20% of oxygen and helium followed by nitrogen

before sealing (Powrie et al., 1990).

Minimally processed fruits or vegetables should be carefully handled because their

natural protection which is the skin, has been removed. Therefore, the packaging

materials must have adequate gas exchange in order to minimize aerobic respiration and

to prevent anaerobic respiration (Latifah et al., 2002). The most common packaging

practices are by using plastic bags and clear plastic containers with lids. Sealed-package

is also used in packaging and this type of packaging alters the concentration of

iratory gases inside the package to create modified atmosphere system (Mohd Salleh

et a/., 1999).

8

CHAPTER 3

MATERIAL AND METHODS

3.1 Material

Matured and fresh fruits of honey pomelo grown in Sungai Sardit and Nanga Singat of

Sibu Division were harvested for use in this study. Some fresh fruits were also obtained

from Kabuloh, Miri Division. The fresh fruits were packed in cardboard box and

transported to AgriculturaJ Research Centre Semongok, Kuching by air transport.

3.2 Methods

fter arrival, the fresh fruits were taken out from the cardboard box. Fruits of suitable

size were selected for the study (Plate 3.1). Choosing suitable size of honey pomelo was

made to achieve uniformity in size for minimal processing. The selected fruits were

washed with clean water to remove dirt and stain. After washing, the fruits were air­

dried. Then, the fruits were wrapped with old newspapers to avoid moisture loss. The

fruits were placed carefully in the baskets and stored in the chiller room at 1 DOC, if not

processed immediately (Plate 3.2 and 3.3).

9

Plate 3.1 Size of honey pomelo chosen for minimal processing

Plate 3.2 Chiller room where the honey pomelo fruit are stored before and after processing

Plate 3.3 Inside the chiller room

10

3.2.1 Peeling process

The selected fruits were taken out from the chiller room for minimal processing (Plate

3.4). Before peeling, the fruits were washed and dipped in 150 ppm of chlorinated water

for 10 minutes for surface sterilization (Plate 3.5). This concentration of chlorinated

water was prepared by dissolving 2 chlorine tablets in approximately 25t of water. The

active ingredient of the chlorine tablet is sodium hypochlorite (NaOel). All appliances

such as stainless steel knives used for peeling were also sterilized with 150 ppm of

chlorinated water (Plate 3.6). After washing and surface sterilization, the fruits were

placed carefully into the baskets and air-dried (Plate 3.7 and 3.8). After drying, the fruits

were brought to the processing room for peeling.

During the peeling, the operators were wearing clean disposable plastic gloves, face

masks, disposable plastic aprons and plastic caps to ensure all processes were handled

under hygienic conditions (Plate 3.9 and 3.10). The fruits were peeled carefully on clean

stainless steel benches that had been covered with clean plastic to avoid surface

contamination (Plate 3.11). Absorbent tissue was placed in each plastic container before

placing the edible segments to absorb water (Plate 3.12). The edible segments were

carefully placed into the plastic containers to avoid breakage (Plate 3.13 and 3.14).

Then, the processed samples were placed in the baskets to be stored (Plate 3.15).

II

The processes of surface sterilizing, peeling and packaging of honey pomelo fruits are

shown in the figures below:

Plate 3.4 Honey pomelo fruits after been taken out from the chiller room for surface sterilization

Plate 3.S Surface sterilizing of honey pomelo fruits in 150 ppm of chlorinated water

Plate 3.6 Sterilization by dipping knives in 150 ppm of chlorinated water

12

Plate 3.7 Placing the fruits in clean fruit baskets for air-drying after sterilization

Plate 3.8 Air-drying the fruits after washing

Plate 3.9 Operators wearing clean disposable apron while peeling the fruits

13