UNIVERSITI PUTRA MALAYSIA SULPHUR DIOXIDE:...

UNIVERSITI PUTRA MALAYSIA

SULPHUR DIOXIDE: COMPARATIVE STUDY OF THREE ANALYTICAL METHODS AND

DETERMINATION IN MALAYSIAN FOODS

NIK SHABNAM BINTI NIK MOHD. SALLEH

FSMB 1998 14




MASTER OF SCIENCE UNIVERSITI PUTRA MALAYSIA

1998



BY


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

in the Faculty of Food Science and Biotechnology Universiti Putra Malaysia.

June 1998

Dedicated to my husband, Ahmad Faisal Zakaria

children, Sarah and Sariha

parents, Allahyarham Nik Mohd. Salleh Nik Mat Nik Latifah Nik J aafar

11

ACKNOWLEDGEMENTS

Alhamdulillah, first of all I would like to express my utmost thanks and

gratitude to Almighty Allah S.W.T. who has given me the capability to complete this

project and my salawat and salam to His righteous messenger, prophet Muhammad

s.a.w.

I would like to take this opportunity to express my sincere appreciation and

gratitude to the Chairman of my Supervisory Committee, Dr. Sharifah Kharidah Syed

Muhammad of the Department of Food Science, Faculty of Food Science and

Biotechnology for her invaluable guidance and encouragement throughout the project.

I am also very grateful to my co-supervisors, Prof. Dr. Gulam Rusul Rahmat Ali, the

Dean ofthe Faculty of Food Science and Biotechnology; Dr. Tee E Siong, Director of

the Division of Human Nutrition, Institute for Medical Research and Dr. Azizah Abdul

Hamid of the Department of Food Science, Faculty of Food Science and

Biotechnology for their constructive comments towards the preparation of this thesis.

Many thanks and appreciation also due to all the Heads of Department and the

staff in the Faculty of Food Science and Biotechnology for their co-operation,

Malaysian Department of Public Services and Ministry of Health for making it

possible for her to undergo her Master of Science programme. Acknowledgement is

also due to Universiti Putra Malaysia for their financial assistance (IRP A Grant No.

50323).

III

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 LIST OF TABLES. . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x LIST OF FIGURES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XUl ABSTRACT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XIV ABSTRAK... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XVI

CHAPTER

I GENERAL INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

II LITERATURE REVIEW.. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 6

Physical and Chemical Properties . . . ... . . . . . . . . ... . . . . . . . . . .. . . . 7

Uses and Effects of Sulphur Dioxide in Foods. . . . . . . . . 8

Inhibition of Non-enzymic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Inhibition of Enzyme-catalysed Reactions ...... 17

Inhibition and Control of Micro-organisms .. . . . . 18

Use as an Anti-oxidant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Use as a Reducing Agent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 2 1

Safety for Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1

Toxicology of Sulphites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Acute Toxicity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Subchronic Toxicity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Chronic Toxicity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Biochemical Behaviour. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Controversy Over The Use of Sulphur Dioxide. . . . . . . . . 25

iv

III

Regulatory Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . 27

International Regulatory Status.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Malaysian Regulatory Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Chemical Fonns of Sulphur Dioxide in Foods.. ... . . . . . . . . . . . . . . . . . . . 33

Detennination of Sulphur Dioxide.. . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . .... . . 34

Methods for the Detennination of Free and Total Sulphur Dioxide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Comparative Studies of Methods for the Determination of Sulphur Dioxide . . . .... . . . . . . . . . . . . . ..... . . . . . .... . . ....... . . . . . . . . ,. . . . . . . .. . . . . . . . . . . . . .. . 49

EVALUATION OF METHODS FOR SULPHUR DIOXIDE DETERMINATION IN FOODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . 55

Introduction. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . .. . . . . . ... ... . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Materials and Methods......................................................................... 57

Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Food Samples. . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Sample Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . . . . . . . . . . . . . . . 58

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Comparative Study. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Statistical Analyses. . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Results and Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 63

Comments on Practical Aspects of Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Mean Values and Variability of Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Recovery Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . ......... ................... . . .... . . . . . 69

Cost Involved in Each Method. . . . ... . . . . . . ..... . . ................. . ........ ....... 73

v

Conclusion.... . ... . . ..... . . . . . . . . ..... ......................... . . ....... ........... . . . ... ... ..... . . . . . . . . . . . 74

IV EVALUATION OF METHODS FOR FOODS WITH LOW CONCENTRATION OF SULPHUR DIOXIDE....................... ........... ........... . . . . ......... ......... . . .. . .. . 75

Introduction... . . . . . .. . . . ........... ............ . ........... ...... . . . . . . . . . . ..... ... .......... ... . . ... . . . . . . 75

Materials and Methods.. . . . . . .. . ...... . . . ... . . . ........ . . . ... . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 76

Chemicals . . . . .. . . . . ..... ...... . ..... . . . .... . . . . . . . . . . .. . . . . . . ... . . . ... . . . . . . . . . . . . . . . . . .. . . . . . . 76

Food Samples. ... . .. . .. . ....... . . . . ....... . ... . . . . . . . . .. .. . . ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Sample Preparation.. .......... . . . . . . . . . . . .. . . ..... . . . . . . . . . . . . . . . . . . . . . . . . ......... .... . . . . 77

Methods. . . . . . . . ................ . . . . . . ....... .. . .......... . . . . .. . . .. . ... . . . . . . . ........ . .. .. . . . .. 77

Comparative Study..... . ....... ... ..... . . . . . . . ... ... ......... . . . . . .. . . . . . . . . . . . . . ..... . . . .. . . . . . . . . . . . . 79

Statistical Analyses. . . .... . . . . . . . . . . . . . . . . .. . . . . . ... ....... . . . . . . . . . . . . . . ..... . . . . . . . . . . . . . . . . . . . . . . . . . 79

Results and Discussion. . . . .. . . . . . . . . . . . . . . . .. . . . . . .... . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Comments on Practical Aspects of Methods.. ... . . . . . . . . . . . . . ... . . . . . . . . . . . . . 80

Mean Values and Variability of Methods. . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . 80

Recovery Values. . ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Conclusion. . . . . . . . . . . . . . . . . . .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

V CORRELATION BETWEEN SHIPTON AND WEDZICHA METHODS IN SULPHUR DIOXIDE DETERMINATION.. . . . . . . . . . . . . . . . . . . 89

Introduction . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Materials and Methods. . . ... . . . . . . . ...... . . . . .. . .......... . . . . . . . . . . . . . . . . . . ... . . . ... . . . . . . . . . . . . . . . . 90

Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Materials. . ..... . . . . . . . . . . ... ... ... . .. . . . . . . . . . . . . . . ... . . ... . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . 91

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Sample Preparation......................................................................... 91

Methods........................................................................................ 92

Results and Discussion.............................................................................. 92

Sulphur Dioxide Detennination by the Shipton and Wedzicha Methods According to its Concentration in Foods.......................... 93

Detennination of Sulphur Dioxide in Foods with High Concentration of Sulphur Dioxide (> 200 ppm) by the Shipton and Wedzicha Methods..... ...... ............ ..... .............. ... ..... ........ .... 93

Detennination of Sulphur Dioxide in Foods with Moderate Concentration (50-200 ppm) by the Shipton and Wedzicha Methods....................................................................................... 97

Detennination of Sulphur Dioxide in Foods with Low Concentration of Sulphur Dioxide «50 ppm) by the Shipton and Wedzicha Methods....................................... ....................... 1 02

Detennination of Sulphur Dioxide by the Shipton and Wedzicha Methods By Different Food Groups............................................ 112

Conclusion................................................................................................. 126

VI THE PREVALENCE OF SULPHUR DIOXIDE IN FOODS................ 128

Introduction............................................................................................ 128

Results and Discussion.............................................................................. 1 30

Sulphur Dioxide Concentration in Food..................................................... 130

Labeling of Food Packages....................................................................... 142

The Average Daily Dietary Intake of Sulphur Dioxide (DDI).............. 152

Conclusion....................................................................................... 157

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VII SUMMARY AND RECOMMENDATION ................. .......... . .... . . . 159

REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 61

APPENDICES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

BIOGRAPHICAL SKETCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

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LIST OF APPENDICES

Appendix Page

A Schematic Diagram of the Apparatus for the Shipton's 170 Modification of Monier-Williams' Distillation Method

B Schematic Diagram of the Apparatus for the Modified 171 Rankine Method

C Schematic Diagram of the Apparatus for the Iodine 172 Distillation Method

D Schematic Diagram of the Apparatus for the Wedzicha 1 73 Method

E Standard Curve for Sulphur Dioxide (Wedzicha 174 Method)

IX

LIST OF TABLES

TABLE Page

1 Major Functions of Sulphites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2 Major Applicatons of Sulphite and Levels of Use. . . . . . . 12

3 Approximate Sulphite Contents in Average Servings of Selected Foods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 26

4 The Foods in Which Sulphur Dioxide may be Used and The Maximum Permitted Proportion of Sulphur Dioxide as specified in the Food Regulations 1985. . . . . .. . . . . . . . . . . . . . . 31

5 Alternative Techniques for Measurement of Free and Total SUlphite in Foods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

6 Comparative Studies on the Methods of Analysis in the Determination of Sulphur Dioxide in Foods... . . . . . . . . . . . . . . . . 52

7 Concentration of Sulphur Dioxide (mg/kg) in Eight Different Foods Obtained from Three Methods of Determination. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

8 Recovery (%) of Sulphur Dioxide by the Shipton, Rankine and Iodine Distillation Methods for Foods Spiked with Various Concentration of Sulphur Dioxide. . . 71

9 Cost of Equipment and Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

10 Concentration of Sulphur Dioxide (mg/kg) in Eight Different foods Obtained by the Shipton and Wedzicha methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

11 Recovery (%) of Sulphur Dioxide by the Shipton, Rankine and Iodine Distillation Methods for Foods Spiked with Various Concentration of Sulphur Dioxide . . . . . 84

12 Cost of Equipment and Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

13 Concentration of Sulphur Dioxide (ppm), Standard Deviation (sd),Coefficient of Variation (cv) and Statistical Analysis (T -test) for Foods with Moderate Sulphur Dioxide Content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

14 Concentration of Sulphur Dioxide (ppm), Standard Deviation (sd), Coefficient of Variation (cv) and Statistical Analysis (T -test) for Foods with Moderate Sulphur Dioxide Content. . . . . . . . . . . . . . . . . . . . . ... . . . . . . . .. . . . . . . . . ... . . . . . . . 98

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1 5 Concentration of Sulphur Dioxide (ppm), Standard Deviation (sd), Coefficient of Variation (cv) and Statistical Analysis (T -test) for Foods with Low Sulphur Dioxide Content.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

1 6 Coefficient of Determination (r) and Coefficient of Correlation (r) Values the Different Classes of Foods . . . . . . . 112

1 7 Sulphur Dioxide in Potato Products as Determined by the Shipton and Wedzicha Methods . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . . . 113

18 Sulphur Dioxide in Jam and Marmalade as Determined by Shipton and Wedzicha Methods . . . . . . . . . . . . . . . . .. . . . ... . . . . . . . . . . . 113

19 Sulphur Dioxide in Cordial and Drink Base as Determined by the Shipton and Wedzicha Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . , 114

20 Sulphur Dioxide in Carbonated Drinks as Determined by the Shipton and Wedzicha Methods . . . . . . . . . . . . . . . . ..... . . . .. . . 1 15

21 Sulphur Dioxide in Fruit Juice as Determined by the Shipton and Wedzicha Methods . . . . .... . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . 116

22 Sulphur Dioxide in Pasta Products as Determined by the Shipton and W dzicha Methods . . . ..... . . . . . . . . . . .. . . . . . . ...... . . . . . . . . . 117

23 Sulphur Dioxide in Sauce and Sauce Mix as Determined by the Shipton and Wedzicha Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

24 Sulphur Dioxide in Snacks as Determined by the Shipton and Wedzicha Methods ............................................................ 118

25 Sulphur Dioxide in Vegetable Products as Determined by the Shipton and Wedzicha Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 8

26 Sulphur Dioxide in Glaced Fruits as Determined by the Shipton and Wedzicha Methods ........................................ 119

27 Sulphur Dioxide in Dried Fruits as Determined by the Shipton and Wedzicha Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

28 Sulphur Dioxide in Pickled Fruits as Determined by the Shipton and Wedzicha Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

29 Sulphur Dioxide in Miscellaneous Foods as Determined by the Shipton and Wedzicha Methods . . .. . .. . .. . . . . . .... . . . . . . . . . . 122

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30 Paired T -test of Sulphur Dioxide Concentration as Determined by the Shipton and Wedzicha Methods.... . . . . . . .. . . .. . .. . . . . . .. . . . . . . .. . . . . . . . . . . . .. . . . 124

31 A Summary of the Coefficient of Determination (i) and Coefficient of Correlation (r) in the Different Food Groups... ... . .. . . . 125

32 Concentration of Sulphur Dioxide in Foods and Maximum Permitted Proportion (mglkg). . . . . . . . . . . . . . . . . . . . .... . . . . ... . . . ... . . . . . . ........ ...... 131

33 Samples Which Contravene the Food Regulations 1 985 in the Sulphur Dioxide Concentration. . . . . . . . . . . . . . . . . . . . . . . . . ... . . . .... . . . . . .. . . .. . .. .. . . . 140

34 Labelling Declaration of Food Samples. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

35 Sulphur Dioxide Content of Selected Foods Presented as mg per 100g Food and per Serving of Foods. . . . . . . . . . ... . . . . . . . . . .... . . . . . .. . . . . . . . . . . . 153

36 A Sample of Three-Day Food Consumption Pattern of a Malaysian diet. . . . . ... . . . .. . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . ... .... . . .... .. 156

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LIST OF FIGURES

Figure Page

1 An Outline ofthe Species Resulting from the Addition of Sulphite to a Food . ..... . ... . . . ... . . .... ...... ..... ..... 34

2 Scatter Plot for the Correlation Between the Shipton and Wedzicha Methods for Foods with High Sulphur Dioxide Content. . . ... . . .. . . . . . . . . ... . . . . . . . . ... . . ... . . . .. . . . .. 109

3 Scatter Plot for the Correlation Between the Shipton and Wedzicha Methods for Foods with Moderate Sulphur Dioxide Content. ................................................ 1 10

4 Scatter Plot for the Correlation Between the Shipton and Wedzicha Methods for Foods with Low Sulphur Dioxide Content. . ... . . ... . . .. . . . .... . ... . . . . . . . ... . . ... . . . . . . . . 1 1 1

X1l1

Abstract of Thesis Submitted to the Senate ofUniversiti Putra Malaysia in Fulfilment of the Requirements for the Degree of Master of Science.

SULPHUR DIOXIDE: COMPARARIVE STUDY OF THREE ANALYTICAL METHODS AND


by

NIK SHABNAM BT. NIK MOHD. SALLEH

June 1998

Chairman: Dr.Sharifah Kharidah Syed Muhammad

Faculty : Food Science and Biotechnology

The study was conducted in four phases. In the first phase, three methods of

analysis were studied on eight different types of foods. The methods were (i) the

Shipton's modification of the Monier-Williams' method or the Shipton method, (ii)

the modified Rankine method, and (iii) the Iodine distillation method. The eight types

of foods were meehoon, orange cordial, mashed potato (granule), pickled nutmeg,

strawberry jam, mayonnaise, orange juice and wine. Comparative studies showed that

the Iodine distillation method gave the highest mean values followed by the Shipton

and modified Rankine methods, and this was true for seven out of the eight types of

food studied. Recovery studies showed that the Shipton method was reliable for foods

with sulphur dioxide content of more than 50 ppm, namely meehoon, cordial, mashed

potato(granule) and pickled nutmeg.

XIV

The second phase focussed on the study of methods for foods with less than 50

ppm, that is strawberry jam, mayonnaise, orange juice and wine. The methods were

(i) the Shipton method, and (ii) the Wedzicha method. Comparative studies showed

that results obtained by the Shipton method were higher than those obtained by the

Wedzicha method, and this was true for all the foods studied. From the recovery

studies, it was found that the Wedzicha method was the method of choice for foods

with less than 50 ppm of sulphur dioxide although it is also reliable for foods which

contain more than 50 ppm sulphur dioxide.

The correlation between the Shipton and Wedzicha methods were studied in

the third phase ofthe study. It was observed that the methods showed good correlation

for foods with sulphur dioxide content of more than 200 ppm, moderate correlation for

food with sulphur dioxide content of between 50 - 200 ppm and bad correlation for

food with sulphur content of less than 50 ppm.

The prevalence of sulphur dioxide in eighty-six types of foods were studied in

the last phase. It was found that 30.23 % ofthe foods contravene the Food Regulations

1 985 in the sulphur dioxide content. The estimate of the Daily Dietary Intake (DDI)

was calculated and it was much lower than the Acceptable Daily Intake (ADI) for

sulphur dioxide.

xv

Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi syarat keperluan untuk Ijazah SaIjana.

SULFUR DIOKSIDA : KAJIAN PERBANDINGAN TIGA KAEDAH ANALISIS DAN

PENENTUAN DALAM MAKANAN DI MALAYSIA

oleh

NIK SRABNAM BT. NIK MOHD. SALLER

Jun 1998

Pengerusi : Dr. Sharifah Kharidah Syed Muhammad

Fakulti : Sains Makanan dan Bioteknologi.

Kajian ini telah dilaksanakan di dalam empat fasa. Di dalam fasa pertama, tiga

kaedah analisis telah dikaji keatas lapan jenis makanan. Kaedah-kaedah tersebut ialah

(i) kaedah Monier-Williams' yang telah diubahsuai oleh Shipton atau kaedah Shipton,

(ii) kaedah Rankine yang telah diubahsuai, dan (iii) kaedah penyulingan iodin. Lapan

jenis makanan yang dikaji ialah meehoon, kordial oren, ubi kentang lecek (serbuk),

buah pala jeruk, jem strawberi, mayonis, jus oren dan wain. Kajian perbandingan

menunjukkan bahawa kaedah penyulingan iodin memberikan nilai min yang paling

tinggi diikuti dengan kaedah Shipton dan kaedah Rankine yang telah diubahsuai, dan

ini adalah benar bagi tujuh dari lapan jenis makanan yang dikaji. Kajian "recovery"

menunjukkan bahawa kaedah Shipton adalah kaedah yang boleh dipakai untuk

makanan yang mempunyai kandungan sulfur dioksida melebihi 50 bsj, iaitu meehoon,

kordial oren, buah pala jeruk dan ubi kentang lecek (serbuk).

XVI

Fasa kedua menumpukan perhatian kepada kaedah-kaedah untuk makanan

yang mempunyai kandungan sulfur dioksida kurang daripada 50 bsj, iaitu jem

strawberi, mayonis, jus oren dan wain. Kaedah-kaedah tersebut ialah (i) kaedah

Shipton, dan (ii) kaedah Wedzicha. Kajian perbandingan menunjukkan bahawa

keputusan yang diperolehi dari kaedah Shipton adalah lebih tinggi dari kaedah

Wedzicha, dan ini adalah benar bagi semua jenis makanan yang dikaji. Daripada

kajian "recovery", adalah didapati bahawa kaedah Wedzicha adalah kaedah yang boleh

dipakai untuk makanan yang mempunyai kandungan sulfur dioksida kurang daripada

50 bsj, walaupun ia boleh juga diterima bagi makanan yang mengandungi lebih dari

50 bsj sulfur dioksida.

Korrelasi di antara kaedah-kaedah Shipton dan Wedzicha telah dikaji di fasa

ketiga kajian ini. Adalah didapati bahawa kedua-dua kaedah menunjukkan korrelasi

yang baik untuk makanan yang mempunyai kandungan sulfur dioksida melebihi 200

bsj, korrelasi sederhana untuk makanan yang mempunyai kandungan sulfur dioksida

di antara 50- 200 ppm dan korrelasi yang lemah bagi makanan yang mempunyai sulfur

dioksida kurang daripada 50 bsj.

Kehadiran sulfur dioksida di dalam lapan-puluh enam jenis makanan telah

dikaji di fasa akhir. Sebanyak 30.23 % daripada makanan tersebut didapati melanggar

Peraturan-Peraturan Makanan 1985 dalam kandungan sulfur dioksida. Anggaran

pengambilan diet harian sulfur dioksida telah dikira dan didapati lebih rendah daripada

pengambilan harian yang boleh diterima.

XVll

CHAPTER I

GENERAL INTRODUCTION

Sulphur dioxide is the most commonly used food preservative. It belongs to

the group of food additives known as sulphiting agents which can be defined as ionic

species that form sulphur dioxide. Sulphur dioxide is present in foods as a result of

the addition of salts of sulphites, bisulphites or metabisulphites.

Sulphur dioxide is permitted in a broad range of foods and beverages including

pickled fruits, dried fruits, soft drinks, fruit juices, j elly and sauces. Sulphur dioxide

is essential in the preservation of these foods because it increases storage life,

preserves colour and flavour and aids in the retention of ascorbic acid and carotene.

Maximum permitted levels of sulphur dioxide in foods are stipulated in the Malaysian

Food Regulations 1985. The maxima stated in the regulations relate to the total

amount present calculated as sulphur dioxide weight by weight. Where a limit is not

specified for sulphur dioxide in the regulations, it is not permitted to be added to that

food.

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2

Although sulphur dioxide has been recognised as a safe food additive, its safety as a

food ingredient needs to be studied in the local context. Whether or not a particular

dietary component or food ingredient poses a hazard to human health depends on a

combination of factors which include:

(i) the concentration of the food component in foods;

(ii) the amount of the foods consumed;

(iii) individual susceptibility to the substance; and

(iv) any interactions between the substance and other dietary components

that could modify its toxicity.

Thus, a particular food ingredient will only become hazardous if it can exert its

harmful effect under the circumstances of exposure to it.

The concentration of the sulphur dioxide in foods is regulated by the food

legislations to ensure that the public is protected against health hazards and fraud in

the preparation, sale and use of food. The Malaysian Food Act 1983 and the Food

Regulations 1985 were adopted from the food laws of several developed countries.

This is acceptable as international differences in food legislations will form a

significant barrier to trade between countries. However, the concentration of sulphur

dioxide recommended may be suitable in those developed countries from where the

regulations were adopted. It has not taken into consideration factors such as socio

economic status, climate, food consumption habits and types of foods consumed. The

records of the monitoring activity on the use of sulphur dioxide in foods by the

3

Ministry of Health, Malaysia have shown that the contravention in the use of sulphur

dioxide is most common in foods such as pickled fruits and noodles. The contravening

levels detected could be the actual concentration of sulphur dioxide in those foods or

the concentrations which were underestimated or overestimated depending on the

method of analysis used by the Department of Chemistry, Malaysia. For foods that do

not have standard methods for analysis, an evaluation of the methods that are available

in the literature for application to those foods should be performed. The method of

sulphur dioxide determination involves the liberation and detection of the liberated

sulphur dioxide. Comparative studies that have been carried out on the liberation and

detection procedures are few and are not thorough in that they only consider a small

number of procedures or food samples. Thus, the fIrst aim of this study is to evaluate

analytical methods for the determination of sulphur dioxide in local foods. The

selected method or methods is or are then used to determine the concentration or

prevalence of sulphur dioxide in our foods. This is the second aim of this thesis and

the data obtained would subsequently assist in the estimation ofthe daily dietary intake

of sulphur dioxide for Malaysians.

Limiting the concentration of a food component by food legislation only partly

controls the hazard that might be associated with it. Generally, for individuals who

consume much higher than the average amounts of a particular food, such measures

would only provide limited protection. Sulphur dioxide has not been known to affect

people at the levels permitted to be added to food. However, it can cause allergic

4

responses in some people such as asthmatics even at or below permitted levels. Results

of studies copducted in the United States showed that not all asthmatics will show a

reaction after ingestion of sulphited foods at permitted levels. The likelihood of a

reaction however, is dependent not only on the level but also on the nature of the food,

its acidity and the sensitivity of the consumer.

The eating habits of people from different countries differ, that is, some have the

tendency of eating certain foods more than others. As such, the upper limit for the

concentration of sulphur dioxide can only be specified for particular foods when the

amounts of the particular foods consumed by the individuals are known. Some of the

foods which contain sulphur dioxide and which are common in the Malaysian diet are

noodles, pickled fruits and vegetables, dried fruits, jams, fruit juices, cordials and

carbonated drinks. With these in mind, the third aim of this thesis is therefore, as

mentioned earlier to estimate the daily dietary intake of sulphur dioxide for Malaysians.

The findings would be useful in:

(i) ascertaining whether the consumers are at risk or not by eating the food

containing sulphur dioxide by comparing the Daily Dietary Intake

(DDI) with the Acceptable Daily Intake (ADI),

(ii) determining whether there is a relationship between any observed

health effects and the intake of sulphur dioxide, and

(iii) providing indications as to whether the existing regulatory limits for

sulphur dioxide in foods should be reviewed.

5

In summary, the specific objectives of this thesis are as follows:

(i) to conduct a comparative study of several methods for the

determination of sulphur dioxide in foods and to identify the most

accurate, reliable and economical method;

(ii) to determine the concentration or prevalence of sulphur dioxide

in a variety of local foods; and

(iii) to estimate the daily dietary intake (DDI) of sulphur dioxide and

to determine whether the daily dietary intake of sulphur dioxide exceed

the Acceptable Dietary Intake (ADI) as set by the Codex Alimentarius

Commission (CAC) and the Food and Agriculture Organisation (F AO)/

World Health Organisation (WHO) Committee on Food Additives and

subsequently constituting a health risk to the consumers.

CHAPTER II

LITERATURE REVIEW

This chapter discusses the properties of sulphur dioxide, its uses and effects

in foods, safety for use, toxicology, controversy over its use and regulatory status.

The quantification of sulphur dioxide is also discussed in great detaiL

Sulphur dioxide (S02) has long been known for its purifying ability.

Sulphur dioxide, made on the spot by burning sulphur has been used since the time

of Homer for fumigating houses and is supposed to have been used by the Romans

and Egyptians for sanitizing wine vessels. Its use as a food preservative is more

recent since the earliest reference that could be found in the literature was a

suggestion in the seventeenth century, that casks should be filled with cider whilst

they still contained sulphur dioxide, produced by burning sulphur in them (Roberts

and Mc Weeny; 1972 ), this was a logical extension of its already known ariliseptic

properties (Roberts and McWeeny, 1972 ) .

Sulphur dioxide was probably first used for the preservation of fruits and

vegetables and their products, but the absence oftoxic hazards associated with its

use ( Roberts and McWeeny, 1972 ) has led to its widespread use in the food

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