The Chemistry of Food Additives and Preservatives

Food additives are chemicals or ingredients that are added to food during processing to improve quality, flavour, appearance or nutritional value, or to prevent chemical or microbial spoilage. The most common types of additives are preservatives, colourants, sweeteners, flavourings, emulsifiers, thickeners and stabilisers. Adding new ingredients to a food has an effect upon its chemistry and structure as well as its sensory characteristics. Additives are usually characterised by where they come from (for example, whether they are natural or synthetic), by their purpose (such as improving shelf life) and the risks associated with them (such as their toxicity, and any side effects upon the consumer). Although in recent years the trend in consumer marketing has been to trumpet a lack of additives and preservatives, with ?artificial ingredients? commonly seen in a negative light, there nevertheless remains a wide variety of additives and preservatives that are crucial both to producers and consumers, without which the quality of the food would suffer.

Chemistry of Food Additives and Preservatives is an up-to-date reference guide to the wide range of different types of additives used in the food industry today. It looks at the processes involved in adding preservatives and additives to foods, and the mechanisms and methods used. The book provides full details about the chemistry of each major class of food additive, showing the reader not just what kind of additives are used and what their functions are, but also how they work, and how they may have multiple functionalities. This book also covers numerous new additives currently being introduced, how the quality of these is ascertained, and how consumer safety is ensured.

Chemistry of Food Additives and Preservatives is an ideal reference for food chemists, food safety specialists and agencies, food processors who are working with additives and preservatives, and food regulators and policy makers. Written in an accessible style and covering a broad range of food additives and preservatives, the book offers an in-depth analysis of the chemical interactions of food additives and preservatives with the natural composition of the foods to which they are added. It is a unique and ground-breaking treatment of a topic vital to both the food industry and the researcher.

Preface ix

Introduction x

List of Abbreviations xiii

1 Antioxidants and Radical Scavengers 1

1.1 Chemistry of free radicals and antioxidants 1

1.2 Types of antioxidants 4

1.3 Efficacy of different antioxidants 7

1.4 Action mechanisms of antioxidants 9

1.5 Structure–activity relationship of antioxidants 11

1.6 Factors affecting antioxidant activity 14

1.7 Quality assessment of dietary antioxidants 15

1.8 How safe are food antioxidants? 23

1.9 Summary 25

References 25

Further reading 31

2 Emulsifiers 33

2.1 Mechanisms of food emulsifiers 33

2.2 The role of emulsifiers in foods 35

2.3 Classification of emulsifiers 37

2.4 Types of food emulsifiers 38

2.5 Quality and analysis of food emulsifiers 58

2.6 Foods containing emulsifiers 60

References 62

Further reading 64

3 Stabilisers, Gums, Thickeners and Gelling Agents as Food Additives 67

3.1 Introduction to stabilisers, thickeners and gelling agents 67

3.2 Polysaccharides 68

3.3 Protein-based food stabilisers 77

3.4 Quality control of food stabilisers and thickeners 78

3.5 Analytical methods 78

References 80

Further reading 82

4 Sweeteners 83

4.1 Introduction to sweeteners 83

4.2 Properties of sweeteners 84

4.3 Intense sweeteners in foods 86

4.4 Bulk food sweeteners 92

4.5 Quality assurance and quality control 95

4.6 Analytical methods 98

References 98

Further reading 100

5 Fragrances, Flavouring Agents and Enhancers 102

5.1 Introduction to flavours and flavouring agents 102

5.2 Classification of food flavourings 103

5.3 Chemistry of food flavourings 105

5.4 Quality control of flavour compounds 119

5.5 Analytical methods for the analysis of food flavourings 120

References 121

Further reading 124

6 Food Acids and Acidity Regulators 125

6.1 What are food acids and acid regulators? 125

6.2 Types of food acids 126

6.3 Uses of food acids 128

References 129

Further reading 130

7 Food Colour and Colour Retention Agents 131

7.1 Why add colourants to foods? 131

7.2 Classification of food colourants 131

7.3 Overview of colourants 133

7.4 Chemistry of food colourants 143

7.5 Extraction from natural sources 143

7.6 Quality assurance of food colourants 144

7.7 Analytical methods 145

References 145

8 Flour Treatment/Improving Agents 148

8.1 What are flour treatment/improving agents? 148

8.2 Flour maturing agents 148

8.3 Flour bleaching agents 151

8.4 Flour processing agents 154

References 154

9 Anticaking Agents 155

9.1 The caking phenomena 155

9.2 Mechanisms of caking 156

9.3 Classification of anticaking agents 159

9.4 Anticaking agents in use 159

References 160

Further reading 161

10 Humectants 162

10.1 Humectants and moisture control 162

10.2 Classification of humectants 162

References 166

11 Antifoaming Agents 167

11.1 Sources of foam in food processing 167

11.2 Properties of antifoaming agents 168

11.3 Mechanisms of antifoaming and foam destabilisation 168

11.4 Synthetic defoamers 168

11.5 Natural defoamers 170

References 171

12 Minerals and Mineral Salts 172

12.1 The importance of minerals and mineral salts 172

12.2 Inorganic mineral salts 173

12.3 Organic mineral salts 175

References 176

13 Dietary Supplements 177

13.1 Introduction to dietary supplements 177

13.2 Classification of vitamins 178

13.3 Vitamin A (retinols) 179

13.4 Vitamin D (calciferol) 189

13.5 Vitamin E 194

13.6 Vitamin K 196

13.7 Vitamin B 199

13.8 Vitamin C (L-ascorbic acid) 210

13.9 Conclusions 212

References 213

14 Glazing Agents 218

14.1 Introduction to glazing agents 218

14.2 Mineral hydrocarbon glazes 218

14.3 Chemistry of MHCs 220

14.4 Conclusion 222

References 223

15 Preservatives 224

15.1 Preservatives: Past, present and future 224

15.2 Natural food preservatives 226

15.3 Traditional food preservation methods 231

15.4 Artificial preservative agents 232

15.5 Modern food preservation techniques 235

15.6 Safety concerns of food preservatives 237

15.7 Analytical methods for the determination of preservative residues 238

15.8 Conclusions 238

References 238

Further reading 243

16 Nutraceuticals and Functional Foods 244

16.1 What are nutraceuticals? 244

16.2 Classification of nutraceuticals 245

16.3 Mechanisms of action 246

16.4 Conclusion 253

References 254

Further reading 257

17 Nutritional Genomics: Nutrigenetics and Nutrigenomics 258

17.1 Nutrition and gene expression 258

17.2 Nutrigenetic areas of application 260

17.3 Analytical methods for nutrigenetical food functions 268

17.4 Conclusion 270

References 270

18 Probiotic Foods and Dietary Supplements 274

18.1 Microbial gut flora activity 274

18.2 Probiotics and nutrition 275

18.3 Probiotics and health 275

18.4 Safety and stability of probiotics 277

18.5 Suitable dietary carriers for probiotics 278

18.6 Assessment of probiotics in foodstuffs and supplements 279

18.7 Conclusions 280

References 281

19 Prebiotics 285

19.1 Prebiotics and health 285

19.2 Factors that influence the activity and effectiveness of prebiotics 286

19.3 Types of oligosaccharides 286

19.4 Quality assessment of prebiotics 289

19.5 Conclusions 290

References 290

20 Synbiotics 291

20.1 Synbiotic foods and health 291

20.2 Health benefits of synbiotics 292

20.3 Mechanism of action of synbiotics 293

20.4 The future of synbotic foods 294

References 294

21 Microencapsulation and Bioencapsulation 295

21.1 Introduction to microencapsulation and bioencapsulation 295

21.2 Commonly used food-grade microcapsules 297

21.3 Methods of food microencapsulation 303

21.4 Microencapsulation for food colourants 307

21.5 Bioencapsulation for probiotics 309

21.6 Conclusions 310

References 310

General Conclusions 314

Index 315

About the Author

Dr Titus A. M. Msagati is a Senior Lecturer in the Department of Applied Chemistry at the University of Johannesburg, South Africa.