High Temperature Processing of Milk and Milk Products

This book covers many aspects of thermal processing of milk and milk products with particular focus on UHT processing. It commences with an overview of the major thermal processing technologies: thermisation, pasteurisation, extended-shelf-life (ESL), UHT and in-container sterilisation. It discusses the principles of the technologies, the processing and packaging equipment used, processing issues such as temperature-time profiles, heat stability, fouling and cleaning, and the quality and safety aspects of the products produced. It provides a balance of the engineering aspects of the processes and the chemical, microbiological and sensory aspects of the products. The changes that occur in products during processing and storage, and the related defects which can arise, are central to the book. The discussions of these changes will be an aid to industry personnel in identifying the causes of quality defects in these products and devising measures which can be taken to eliminate or minimise the defects.

Autorentext

About the Authors

Hilton C. Deeth, Emeritus Professor, School of Agriculture and Food Sciences, University
of Queensland, Australia, and consultant to the dairy industry

Michael J. Lewis, Honorary Fellow, Department of Food and Nutritional Sciences, Taught and researched at The University of Reading, Whiteknights, UK, for 38 years and now working as an adviser on milk and milk products

Klappentext

High Temperature Processing of Milk and Milk Products covers many aspects of thermal processing of milk and milk products with particular focus on UHT processing.

The book begins with an overview of the major thermal processing technologies: thermisation, pasteurisation, extended-shelf-life (ESL), UHT and in-container sterilisation. It discusses the principles of the technologies, the processing and packaging equipment used, processing issues such as temperature-time profiles, heat stability, fouling and cleaning, and the quality and safety aspects of the products produced. It provides a balance of the engineering aspects of the processes and the chemical, microbiological and sensory aspects of the products. The changes that occur in products during processing and storage, and the related defects which can arise, are central to the book. The discussions of these changes will be an aid to industry personnel in identifying the causes of quality defects in these products and devising measures which can be taken to eliminate or minimise the defects. A unique feature is a chapter on analytical methodologies applicable to thermally processed dairy products. There are also chapters on high-temperature processed products other than white cows' milk, including products based on plant materials, and on non-thermal technologies which may be used in place of or as adjuncts to thermal processing. The book concludes with a chapter outlining some of the challenges with the technologies and treated products, and a compendium of relevant reviews, chapters and books.

Inhalt
About the Authors xv

Preface xvii

List of Abbreviations xxi

1 History and Scope of the Book 1

1.1 Setting the Scene 1

1.2 Scope of the Book 7

1.3 Reasons for Heating Foods 7

1.4 Brief History of Sterilisation Processes 8

References 12

2 Heat Treatments of Milk Thermisation and Pasteurisation 15

2.1 Introduction 15

2.2 Thermisation 16

2.3 Pasteurisation 17

2.3.1 Introduction 17

2.3.2 Historical Background 18

2.3.3 Pasteurisation Equipment 21

2.3.4 Process Characterisation 24

2.3.5 Processing Conditions 27

2.3.6 Changes During Pasteurisation 28

2.3.7 Changes During Storage 32

2.3.8 Pasteurisation of Other Milk?Based Products 34

References 36

3 Heat Treatments of Milk ESL, UHT and in?Container Sterilisation 41

3.1 Introduction 41

3.2 Some Important Definitions 41

3.2.1 Q10 41

3.2.2 Bacterial Indices, B* and F0 42

3.2.3 Chemical Index, C* 43

3.3 Extended Shelf?Life (ESL) Milk Processing 44

3.3.1 ESL Milk by Thermal Treatment 44

3.3.2 ESL Milk by Microfiltration Plus HTST Heat Treatment 49

3.3.3 ESL Milk by Thermal Treatment Plus Bactofugation 50

3.3.4 ESL Milk by Thermal Treatment Plus an Antibacterial Agent 50

3.3.5 ESL Milk by Thermal Treatment Plus a Non?Thermal Technology Treatment 50

3.3.6 ESL Milk by Multiple Thermal Treatments 51

3.4 Sterilisation 52

3.4.1 Introduction 52

3.4.2 UHT Processing 54

3.4.3 In?Container Sterilisation 58

References 61

4 Microbiological Aspects 65

4.1 Introduction 65

4.2 Bacteria in Raw Milk 65

4.2.1 Non?Spore?Forming Psychrotrophic Bacteria and their Heat?Resistant Enzymes 68

4.2.2 Spore?Forming Bacteria 69

4.3 Heat Inactivation of Bacteria 78

4.4 Microflora in Processed Milks 80

4.4.1 Pasteurised Milk 80

4.4.2 ESL Milk 83

4.4.3 UHT Milk 85

4.4.4 In?Container Sterilised Milk 90

4.5 Sterilisation of Equipment and Packaging to Prevent Microbial Contamination of UHT Products 90

References 91

5 UHT Processing and Equipment 103

5.1 The UHT Process 103

5.2 Heating 104

5.2.1 Steam?/Hot?Water?Based Heating Systems 104

5.2.2 Electrically Based Heating Systems 146

5.3 Homogenisation 150

5.4 Deaeration 154

5.5 Aseptic Packaging 155

5.5.1 Types of Packaging 155

5.5.2 Sterilisation of Packaging 158

5.5.3 Establishing and Maintaining a Sterile Environment 158

5.5.4 Aseptic Package Integrity 159

5.5.5 Validation of Aseptic Packaging Operations 159

5.6 Plant Cleaning and Sanitisation 161

5.6.1 Introduction 161

5.6.2 Rinsing 161

5.6.3 WaterProduct Changeover 162

5.6.4 Cleaning 162

5.6.5 Methods of Measuring Cleaning Effectiveness 164

5.6.6 Kinetics of Cleaning 166

5.6.7 Disinfecting and Sterilising 167

6 Changes During Heat Treatment of Milk 177

6.1 Chemical 177

6.1.1 pH and Ionic Calcium 177

6.1.2 Mineral Salts 182

6.1.3 Proteins 184

6.1.4 Lactose 195

6.1.5 Vitamins 200

6.1.6 Flavour 201

6.1.7 Chemical Heat Indices 208

6.2 Physical Changes 212

6.2.1 Heat Stability 212

6.2.2 Fouling 222

6.3 Kinetics and Computer Modelling 240

References 242

7 Changes During Storage of UHT Milk 261

7.1 Chemical Changes 263

7.1.1 pH 263

7.1.2 Dissolved Oxygen Content 264

7.1.3 Flavour 266

7.1.4 Proteolysis 273 &...