ultraviolet irradiation on pineapple juicepsasir.upm.edu.my/41688/1/fk 2011 137r.pdf · analisis...

UNIVERSITI PUTRA MALAYSIA

CHIA SU LING

FK 2011 137

EFFECTS OF ULTRAVIOLET IRRADIATION ON PHYSICOCHEMICAL, MICROBIOLOGICAL, AND RHEOLOGICAL PROPERTIES OF PINEAPPLE

(Ananas comosus L. VAR. YANKEE) JUICE

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EFFECTS OF ULTRAVIOLET IRRADIATION ON PHYSICOCHEMICAL,

MICROBIOLOGICAL, AND RHEOLOGICAL PROPERTIES OF

PINEAPPLE (Ananas comosus L. VAR. YANKEE) JUICE

By

CHIA SU LING

Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia,

in Fulfilment of the Requirements for the Degree of Master of Science

December 2011

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Specially thanks to….

My parents….

My siblings….

My friends….

For their support and encouragements….

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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfillment

of the requirement for the degree of Master of Science

EFFECTS OF ULTRAVIOLET IRRADIATION ON PHYSICOCHEMICAL,

MICROBIOLOGICAL, AND RHEOLOGICAL PROPERTIES OF

PINEAPPLE (Ananas comosus L. VAR. YANKEE) JUICE

By

CHIA SU LING

December 2011

Chairman: Rosnah Binti Haji Shamsudin, PhD

Faculty: Engineering

Unpasteurised or fresh juice may be contaminated with pathogens or microorganisms

that are harmful to human health. Presently, thermal pasteurisation is the most

common technology used in the fruit juice industry to inactivate enzymes or

microorganisms, but the application of heat adversely affect the nutritional and

sensory qualities of the juice. Ultraviolet (UV) irradiation is a promising disinfection

technology. This nonthermal technology minimizes the loss of flavour and nutritional

qualities of fruit juice. There is no literature available about the application of UV to

pineapple juice. The present study aims to investigate the effect of UV irradiation on

the quality of pineapple juice based on physicochemical, microbiological and

rheological analyses. A UV dosage of 53.42 mJ/ cm2

administered to the pineapple

juice was chosen based on germicidal effectiveness. The UV-irradiated pineapple

juice was similar to the untreated juice in total soluble solids (TSS), pH, titratable

acidity, ascorbic acid, L*, hue angle and chroma parameters, but was significantly

different (p<0.05) compared to the thermally pasteurised pineapple juice. Turbidity

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of pineapple juice was significantly decreased (p<0.05) after UV treatment and

significant increased (p<0.05) after the thermal treatment. A large and significant

reduction (p<0.05) in the total phenolic content was seen in the thermal treatment

group (34.83%) as compared to the UV-irradiated group (16.55%). There was a

significant decrease (p<0.05) in the total plate counts (TPC) and the yeast and mould

counts (YM) in the UV and the thermally treated pineapple juice, although the

thermally treated group was statistically more variable than the UV treatment group.

During the 13 weeks of storage, TSS and titratable acidity of UV-irradiated juice

were significantly decreased (p<0.05) whereas pH and turbidity were significantly

increased (p<0.05). However, these parameters remained stable in thermally

pasteurised juice throughout the storage time. There were no significant changes in

total phenolic for both treatments throughout the storage period. Other quality

parameters (ascorbic acid, L*, hue angle and chroma) were significantly affected by

the storage time in the UV-irradiated and thermally pasteurised juice. Regarding the

microbiological analysis, the TPC and YM of the UV-irradiated juice increased

gradually throughout the 13 weeks of storage while these parameters remained

unchanged in the thermally pasteurised juice with almost no microorganism growth.

A rheological test was performed on untreated, UV-irradiated and thermally

pasteurised juice at temperatures ranging from 5C to 25

C throughout the 13 weeks

of storage. The Bingham model described adequately the rheological behaviour of he

juices. There was no significant variation between the plastic viscosities of the

untreated and UV-irradiated juice at all temperatures. A significant (p<0.05) increase

of plastic viscosity was however observed in the thermal pasteurised juice at

temperature 5C and 10

C. Throughout the 13 weeks of storage, plastic viscosities

of untreated and UV-irradiated juice in the temperature range of 5C to 25

C

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significantly decreased while no significant change was found in thermally

pasteurised juice. The effect of temperature on plastic viscosity was adequately

described by the Arrhenius equation. The results of this study demonstrate the

effectiveness of UV irradiation in preserving the nutritional quality attributes of fruit

juice compared to thermal pasteurisation.

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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai

memenuhi keperluan untuk Ijazah Master Sains

KESAN IRRADIASI ULTRAUNGU KE ATAS SIFAT-SIFAT FIZIKAL-KIMIA,

MIKROBIOLOGI, DAN REOLOGI JUS NANAS (Ananas comosus L. VAR.

YANKEE)

Oleh

CHIA SU LING

Disember 2011

Pengerusi: Rosnah Binti Haji Shamsudin, PhD

Fakulti: Kejuruteraan

Jus segar yang tidak dibasmikan kuman menyebabkan kewujudan bakteria dan

mikroorganisma yang berbahaya kepada kesihatan manusia. Kini, pempasteuran

terma merupakan teknologi yang paling umum digunakan dalam industri jus

buah-buahan untuk mematikan enzim atau mikroorganisma, tetapi aplikasi terma

menjejaskan kualiti nutrisi dan sensori jus. Irradiasi ultraungu (UV) adalah teknologi

pembasmian kuman atau bakteria yang berpotensi. Teknologi bukan terma ini

meminimumkan kehilangan nutrisi dan rasa jus buah-buahan. Tiada kajian tentang

aplikasi irradiasi UV dalam pemprosesan jus buah-buahan. Penyelidikan ini adalah

bertujuan untuk mengetahui kesan irradiasi UV terhadap kualiti jus nanas

berdasarkan analisis fizikal-kimia, mikrobiologi dan reologi. Irradiasi UV pada dos

53.42 mJ/ cm2

dipancarkan ke atas jus nanas dipilih berdasarkan keberkesanan

dalam pembunuhan bakteria dan mikroorganisma. Sifat-sifat fizikal-kimia seperti

jumlah pepejal larut (TSS), pH, keasidan, vitamin C, L*, warna “hue” dan“chroma”

bagi jus nanas yang diiradiasi dengan UV didapati sama dengan jus tanpa rawat.

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Walaubagaimanapun, terdapat perubahan signifikan (p<0.05) dilaporkan bagi jus

pempasteuran terma. Kekeruhan bagi jus nanas yang diirradiasi dengan UV dan

dipasteuri terma masing-masing dilaporkan menurun dan meningkat secara

signifikan (p<0.05). Terdapat penurunan besar dan signifikan (p<0.05) untuk jumlah

fenolik dalam jus pempasteuran terma (34.83%) berbanding dengan jus irradiasi UV

(16.55%). Walaupun pempasteuran terma lebih berkesan dalam pembunuhan

mikroorganisma, tetapi penurunan signifikan (p<0.05) bagi jumlah bilangan plat

(TPC) dan yis serta kulat (YM) didapati juga dalam jus irradiasi UV dan

pempasteuran terma. Bagi jus irradiasi UV, TSS dan keasidan menurun secara

signifikan (p<0.05) manakala pH dan kekeruhan meningkat secara signifikan

(p<0.05) sepanjang 13 minggu penyimpanan. Namun begitu, sifat-sifat fizikal-kimia

ini stabil dalam jus pempasteuran terma sepanjang masa penyimpanan. Tiada

perubahan signifikan jumlah fenolik untuk kedua-dua jenis rawatan sepanjang

penyimpanan. Vitamin C, L*, warna “hue” dan “chroma” untuk jus irradiasi UV dan

pempasteuran terma ada perubahan signifikan semasa penyimpanan. Keputusan

analisis mikrobiologi pula didapati TPC dan YM untuk jus irradiasi UV meningkat

tetapi tiada perubahan dalam jus pempasteuran terma dengan hampir tiada

pertumbuhan mikroorganisma sepanjang masa penyimpanan. Perubahan reologi

semasa penyimpanan bagi jus tanpa rawat, irradiasi UV dan pempasteuran terma

dilakukan pada suhu 5-25

C. Dalam semua kes, sifat-sifat reologi jus nanas

berpadanan dengan model Bingham. Tiada perubahan signifikan untuk kelikatan

plastik jus nanas tanpa rawat dan irradiasi UV pada semua suhu. Namun, kelikatan

plastik jus pempasteuran terma didapati meningkat secara signifikan (p<0.05) pada

suhu 5C dan 10

C. Selain itu, kelikatan plastik jus tanpa rawat dan irradiasi UV

pada suhu 5-25

C menurun secara signifikan (p<0.05) semasa penyimpanan

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manakala tiada perubahan signifikan bagi jus pempasteuran terma. Kesan suhu ke

atas kelikatan plastik jus nanas diterangkan oleh persamaan Arrhenius. Secara

keseluruhan didapati keputusan menunjukkan keberkesanan irradiasi UV dalam

pengekalan kualiti nutrisi jus buaha-buahan berbanding dengan pempasteuran terma.

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ACKNOWLEDGEMENTS

Foremost, I would like to express my sincere gratitude to my advisor, Dr.

Rosnah binti Haji Shamsudin for her expertise, understanding, patience and

encouragement throughout my research project. This thesis would not have been

possible without her guidance and unfailing help.

My deep appreciations are extended to my thesis committee members, Dr.

Noranizan Mohd Adzahan and Prof. Ir. Dr. Hj. Wan Ramli bin Wan Daub for their

kind assistance, wise advices and constructive comments. I wish to express my

sincere thank to Madam Noraziah Muda who contributed useful comments and

advices during analyzing my rheological study results.

I wish to thank the Fundamental Research Grant Scheme (FGRS), project

number 03-04-10-802FR for the financial support and also the Federal Agriculture

Marketing Authority (FAMA) for providing the fruit samples.

I am indebted to many of my friends for helping and supporting me throughout

the difficulties times and caring they provided. I am grateful to all the staffs and

laboratory technicians from Department of Process and Food Engineering and

Faculty of Food Science and Technology that have assisted me during my research

work.

Lastly, and most importantly, I would like to thank my beloved family for their

continuous support and endless love throughout my life.

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I certify that a Thesis Examination Committee has met on 8 December 2011 to

conduct the final examination of Chia Su Ling on her thesis entitled “Effects of

Ultraviolet Irradiation on Physicochemical, Microbiological, and Rheological

Properties of Pineapple (Ananas comosus L. Var. Yankee) Juice” in accordance with

the Universities and University Colleges Act 1971 and the Constitution of the

Universiti Putra Malaysia [P.U.(A) 106] 15 March 1998. The Committee

recommends that the student be awarded the Master of Science.

Members of the Thesis Examination Committee were as follows:

Johari Endan, PhD

Associate Professor

Faculty of Engineering

Universiti Putra Malaysia

(Chairman)

Chin Nyuk Ling, PhD

Associate Professor



(Internal Examiner)

Russly Abdul Rahman, PhD

Professor

Halal Products Research Institue


(Internal Examiner)

Abdul Karim Alias, PhD

Professor

Food Technology

School of Industrial Technology

Universiti Sains Malaysia

(External Examiner)

SEOW HENG FONG, PhD

Professor and Deputy Dean

School of Graduate Studies


Date:

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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been

accepted as fulfillment of the requirement for the degree of Master of Science. The

members of the Supervisory Committee were as follows:

Rosnah Binti Haji Shamsudin, PhD

Senior Lecturer



(Chairman)

Noranizan Mohd Adzahan, PhD

Lecturer

Faculty of Food Science and Technology


(Member)

Wan Ramli Wan Daud, PhD

Professor

Faculty Engineering

Universiti Kebangsaan Malaysia

(Member)

BUJANG BIN KIM HUAT, PhD

Professor and Dean

School of Graduate Studies


Date:

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DECLARATION

I declare that the thesis is my original work except for quotations and citations which

have been duly acknowledged. I also declare that it has not been previously, and is

not concurrently, submitted for any other degree at Universiti Putra Malaysia or at

any other instituition.

CHIA SU LING

Date: 8 December 2011

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TABLE OF CONTENTS

Page

DEDICATION ii

ABSTRACT iii

ABSTRAK vi

ACKNOWLEDGEMENTS ix

APPROVAL x

DECLARATION xii

LIST OF TABLES xvi

LIST OF FIGURES xviii

LIST OF ABBREVIATIONS xxii

CHAPTER

1 INTRODUCTION

1.1 Research Background 1

1.2 Problem Statements 3

1.3 Objectives 4

2 LITERATURE REVIEW 2.1 Introduction 5

2.2 Fruit Juice Market 6

2.3 Pineapple 7

2.3.1 Market for Pineapple Juice 8

2.3.2 Pineapple Juice in Malaysia 9

2.3.3 Nutritional Compositions of Pineapple 11

and Its Health Benefits

2.4 Fruit Juice Production 13

2.5 Fruit Juice Spoilage 14

2.5.1 Foodborne Outbreaks 16

2.6 Regulation of Fruit Juices 18

2.7 Fruit Juice Preservation Methods

2.7.1 Thermal Pasteurisation 19

2.7.1.1 Effect of Thermal Pasteurisation on Food Quality 20

2.7.2 Nonthermal Alternative Processing Technologies 21

2.7.3 Ultraviolet (UV) Irradiation 22

2.7.3.1 Microbial Effects 24

2.7.3.2 Factors Affect Efficiency of Ultraviolet Irradiation 26

2.7.3.3 Ultraviolet Pasteuriser Designs 27

2.7.3.4 Advantages and Limitations of 29

Ultraviolet irradiation

2.7.3.5 Applications of Ultraviolet irradiation 32

2.8 Rheological Properties 33

2.8.1 Effect of Temperature 36

2.8.2 Significances of Rheological Properties 37

2.9 Summary 38

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3 MATERIALS AND METHODS

3.1 Introduction 39

3.2 Research Design 39

3.3 Preparation of Pineapple Juice 42

3.4 Ultraviolet (UV) Irradiation

3.4.1 Ultraviolet Pasteuriser 42

3.4.2 Cleaning of the Ultraviolet Pasteuriser 43

3.4.3 Ultraviolet Treatment 43

3.4.4 Calculation of Ultraviolet Dosage 43

3.4.5 Modeling of Microbial Reduction 50

3.5 Thermal Pasteurisation Treatment 51

3.6 Juice Analysis

3.6.1 Physico-chemical Analysis

3.5.1.1 Total Soluble Solids (TSS) 51

3.5.1.2 Titratable Acidity and pH 51

3.5.1.3 Ascorbic Acid 52

3.5.1.4 Colour 52

3.5.1.5 Turbidity 53

3.5.1.6 Total Phenolic 54

3.6.2 Microbiological Analysis 54

3.6.3 Rheological Analysis 55

3.5.3.1 Rhelogical Modeling Equations 55

3.7 Storage Study 56

3.8 Statistical Analysis 57

3.9 Summary 57

4 RESULTS AND DISCUSSION

4.1 Introduction 59

4.2 Determination of Ultraviolet Processing Parameters 60

4.3 Comparison of Quality Attributes between Ultraviolet Irradiation

and Thermal Pasteurisation

4.3.1 Physico-chemical Properties


4.3.1.2 pH and Titratable Acidity 62


4.3.1.4 Colour 64



4.3.2 Microbiological Properties 69

4.4 Effect of Storage on the Quality Attributes of Ultraviolet Irradiated

and Thermally Pasteurised Pineapple Juice

4.4.1 Physicochemical Analysis


4.4.1.2 pH 73

4.4.1.3 Titratable Acidity 74


4.4.1.5 Colour 78



4.4.2 Microbiological Properties 86

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4.5 Rheological Study of Ultraviolet Irradiated and

Thermally Pasteurised Pineapple Juice

4.5.1 Flow Curves 89

4.5.2 Rheology Model 98

4.5.3 Plastic Viscosity

4.5.3.1 Effect treatment on Plastic Viscosity 108

4.5.3.2 Effect Storage on Plastic Viscosity 110

4.5.4 Effect Temperature on Plastic Viscosty 113

4.6 Summary

121

5 SUMMARY, CONCLUSION AND RECOMMENDATIONS FOR FUTURE

RESEARCH

5.1 Summary and Conclusions 122

5.2 Recommendations for Future Studies 125

BIBLIOGRAPHY 126

APPENDICES 140

BIODATA OF STUDENT 153

LIST OF PUBLICATION AND PROCEEDING 154

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