Provides the most recent developments in microscopy techniques and types of analysis used to study the microstructure of dairy products
This comprehensive and timely text focuses on the microstructure analyses of dairy products as well as on detailed microstructural aspects of them. Featuring contributions from a global team of experts, it offers great insight into the understanding of different phenomena that relate to the functional and biochemical changes during processing and subsequent storage.
Structured into two parts, Microstructure of Dairy Products begins with an overview of microscopy techniques and software used for microstructural analyses. It discusses, in detail, different types of the following techniques, such as: light microscopy (including bright field, polarized, and confocal scanning laser microscopy) and electron microscopy (mainly scanning and transmission electron microscopy). The description of these techniques also includes the staining procedures and sample preparation methods developed. Emerging microscopy techniques are also covered, reflecting the latest advances in this field. Part 2 of the book focuses on the microstructure of various dairy foods, dividing each into sections related to the microstructure of milk, cheeses, yogurts, powders, and fat products, ice cream and frozen dairy desserts, dairy powders and selected traditional Indian dairy products. In addition, there is a review of the localization of microorganism within the microstructure of various dairy products. The last chapter discusses the challenges and future trends of the microstructure of dairy products.
- Presents complete coverage of the latest developments in dairy product microscopy techniques
- Details the use of microscopy techniques in structural analysis
- An essential purchase for companies, researchers, and other professionals in the dairy sector
Microstructure of Dairy Products is an excellent resource for food scientists, technologists, and chemists - and physicists, rheologists, and microscopists - who deal in dairy products.
Table of Contents
List of Contributors xiii
Preface xv
1 Microscopy Techniques for Dairy Products - An Introduction 1
Mark A.E. Auty
1.1 Introduction 1
1.1.1 Brief History and Background 1
1.2 Conventional Optical Microscopy Techniques 4
1.2.1 Conventional Light Microscopy - Optical Contrast 4
1.2.1.1 Bright Field 4
1.2.1.2 Polarized Light 4
1.2.1.3 Phase Contrast 4
1.2.1.4 Differential Interference Contrast 5
1.2.1.5 Fluorescence 5
1.2.2 Chemical Contrast Techniques in Light Microscopy 5
1.3 Confocal Scanning Laser Microscopy 6
1.3.1 Confocal Principle 6
1.3.2 Identifying Dairy Primary Components in CSLM: Labeling Strategies 8
1.3.2.1 Generic Labeling 8
1.3.2.2 Specific Labeling 10
1.3.2.3 Covalent Labeling 11
1.3.3 Some Applications of Confocal Microscopy to Dairy Products and Ingredients 12
1.3.3.1 Spreads 12
1.3.3.2 Emulsions and Foams 12
1.3.3.3 Fermented Milks 12
1.3.3.4 Cheese 13
1.3.3.5 Dairy Powders 13
1.3.3.6 Milk Protein Gel Systems 14
1.3.3.7 Dynamic CSLM Techniques 14
1.4 Electron Microscopy (EM) Techniques 16
1.4.1 Transmission Electron Microscopy 16
1.4.2 Scanning Electron Microscopy 18
1.4.3 Other EM Techniques 18
1.4.3.1 X‐ray Microanalysis 18
1.4.3.2 Cryo‐electron Microscopy 19
1.4.3.3 Environmental and Variable Pressure SEM 20
1.5 Emerging Microscopy Techniques 20
1.5.1 Atomic Force Microscopy 20
1.5.2 Advanced Fluorescence Microscopy Techniques 22
1.5.3 Confocal Raman Microscopy 22
1.5.4 X‐ray Nano/Microtomography 22
1.5.5 Super‐Resolution Microscopy 23
1.6 Image Analysis 23
1.7 Conclusions 24
References 24
2 Light Microscopy and CSLM Techniques, Principles and Applications 33
Johan Hazekamp
2.1 Introduction 33
2.1.1 The History of Microscopy 33
2.1.2 Evolution of Confocal Microscopy 34
2.1.3 Food Microscopy 35
2.1.4 Wide Field Microscopy 36
2.1.5 Confocal Scanning Laser Microscopy (CSLM) 38
2.2 Sample Preparation and Specific Staining and Labeling 41
2.2.1 Specific Labeling 44
2.2.2 Dynamic Imaging 46
2.2.3 Future Perspectives 46
References 47
3 Electron Microscopy Techniques 51
Semih Otles and Vasfiye Hazal Ozyurt
3.1 Introduction 51
3.2 Types of EM 51
3.2.1 Scanning Electron Microscopy (SEM) 51
3.2.2 Transmission Electron Microscopy (TEM) 52
3.2.3 Cryo‐SEM 52
3.2.4 Cryo‐TEM 53
3.2.5 Environmental Scanning Electron Microscopy (ESEM) 53
3.3 Sample Preparation for EMs 53
3.3.1 Scanning Electron Microscopy 53
3.3.2 Transmission Electron Microscopy 53
3.3.3 Cryo‐Scanning Electron Microscopy 53
3.4 Dairy Microstructure 54
3.5 Electron Microscopy for the Dairy Product 54
3.6 Summary 60
References 64
4 Emerging Techniques for Microstructural Analysis 67
I. Hernando, E. Llorca, and A. Quiles
4.1 Introduction 67
4.2 Scanning Probe Microscopy 67
4.2.1 Scanning Tunneling Microscope (STM) 69
4.2.2 Atomic Force Microscope (AFM) 70
4.2.3 Applications of the Main Probe Microscopes 71
4.3 X‐Ray Tomography 72
4.4 Small‐Angle‐Scattering (SAS) Methods: SAXS and SANS 74
4.4.1 Small‐Angle X‐Ray Scattering (SAXS) 74
4.4.2 Small‐Angle Neutron Scattering (SANS) 75
4.4.3 Applications of Small‐Angle‐Scattering Methods 75
4.5 Vibrational Spectroscopies (Fourier Transform Infrared‐FTIR and Raman Microscopy) 75
4.5.1 Fourier Transform Infrared (FTIR) Spectroscopy 76
4.5.2 Raman Spectroscopy 78
4.6 Magnetic Resonance: NMR and MRI 80
4.7 Conclusions 82
References 82
5 Quantitative Image Analysis in Microscopy 89
Gaetano Impoco
5.1 Aim and Scope 89
5.2 Image Analysis Software 90
5.3 Applications to Microscopy for Dairy Science 97
5.3.1 Porosity 98
5.3.2 Fat Globules 99
5.3.3 Microbial Cells 100
5.4 Image Analysis and Quantitative Measurement 100
5.4.1 Image Analysis Basics 101
5.4.1.1 Feature Detection 102
5.4.1.2 Quantitative Analysis 103
5.4.2 Common Pitfalls 105
5.4.3 Misuse and Wrong Interpretation of Image Analysis Results 114
5.4.4 Good Practices 116
5.4.5 Image Analysis in your Lab 119
5.5 Conclusions 122
Acknowledgments 123
References 123
6 Microstructure of Milk 127
Michael H. Tunick
6.1 Components of Milk 127
6.2 Fat 127
6.2.1 Fat Globules 127
6.2.2 Milkfat Globule Membrane 128
6.2.3 Cream 129
6.3 Protein 133
6.3.1 Types of Protein 133
6.3.2 Casein Micelles in Bovine Milk 133
6.3.3 Casein Micelles in Caprine Milk 133
6.3.4 Casein Micelles in Milk of Other Species 136
6.3.5 Micelle Structure 136
6.4 Bacteria and Somatic Cells 137
6.5 Concentrated Milk 138
6.6 Digested Milk 140
6.7 Conclusion 142
Acknowledgments 142
References 142
7 Microstructure of Cheese Products 145
Bhavbhuti M. Mehta
7.1 Introduction 145
7.2 Factors Affecting the Development of Microstructures in Cheeses 146
7.2.1 Addition of Calcium Chloride 148
7.2.2 Rennet Coagulation 149
7.2.3 Acid‐Coagulation 150
7.2.4 Coagulation Temperature 150
7.2.5 Syneresis 151
7.2.6 Salting 151
7.2.7 Ripening 152
7.2.8 Homogenization and High Pressure Treatments 153
7.2.9 Evaporation and Ultrafiltration Treatments 155
7.2.10 Freezing 156
7.2.11 Fat Replacers 156
7.3 Microstructures of Various Components in Cheese Matrix 158
7.3.1 Protein in Cheese Matrix 158
7.3.2 Fat Globule in Cheese Matrix 159
7.3.3 Calcium in Cheese Matrix 162
7.4 Crystals in Cheese Matrix 162
7.5 Starter Bacteria in Cheese Matrix 163
7.6 Microstructure of Selected Varieties of Cheeses 164
7.6.1 Processed Cheese 164
7.6.1.1 Curd Granules and Fat 166
7.6.1.2 Occurrence of Crystals 166
7.6.2 Cheese Analogs 166
7.6.3 Feta Cheese 167
7.6.4 Domiati Cheese 167
7.6.5 Fresh Cheese 167
7.6.6 Cream Cheese 168
7.6.7 Mold‐Ripened Cheeses 169
7.6.8 Cheese Powder 169
7.7 Cheese Matrix and Digestion 170
7.8 Conclusions 171
References 171
8 Microstructural Aspects of Yogurt and Fermented Milk 181
P.H.P. Prasanna, C.S. Ranadheera, and J.K. Vidanarachchi
8.1 Yogurt and Fermented Milk: An Overview 181
8.2 Yogurt and Fermented Milk: Production Technologies 184
8.3 Microstructure of Yogurt and Fermented Milk 187
8.4 Factors Influencing Microstructure of Yogurt and Fermented Milk 188
8.4.1 Effects of Type of Milk on Structure 188
8.4.2 Rate of Inoculation Level and Starter Culture Composition on Microstructure of Yogurt and Fermented Milk 189
8.4.2.1 Rate of Inoculation 189
8.4.2.2 Culture Composition 189
8.4.3 Effect of Exopolysaccharide Producing Starter Culture on Microstructure 190
8.4.4 Incubation Temperature on Structure 191
8.4.5 Effect of Different Processing Steps 191
8.4.5.1 Homogenization of Milk 191
8.4.5.2 Heat Treatment of Milk 192
8.4.5.3 Effect of Stirring 192
8.4.6 Effect of Addition of Different Hydrocolloids and Fibers on Microstructure 193
8.5 Microscopy Methods Used for Analyzing Microstructure of Fermented Milk 194
8.5.1 Light Microscopy 194
8.5.1.1 Bright Field Light Microscopy 194
8.5.1.2 Polarized Light Microscopy 194
8.5.1.3 Fluorescence Microscopy 195
8.5.1.4 Confocal Laser Scanning Microscopy 197
8.5.2 Electron Microscopy 198
8.5.2.1 Scanning Electron Microscopy 198
8.5.2.2 Transmission Electron Microscopy 200
8.6 Conclusions 201
References 202
9 Microstructure of Milk Fat and its Products 209
Pere Randy R. Ramel and Alejandro G. Marangoni
9.1 Introduction 209
9.2 Milk Fat Crystal Structure 211
9.2.1 Mesoscale Structure of Milk Fat 211
9.2.1.1 Polymorphism 211
9.2.1.2 Phase Behavior and Fractionation 213
9.2.1.3 Solid Fat Content and Crystallization/Melting Behavior 214
9.2.2 Nanoscale Structure of Fat Crystal Networks 216
9.3 Effect of Different Factors on the Crystallization Behavior and Microstructure of Milk Fat 218
9.3.1 Processing Conditions 218
9.3.1.1 Different Crystallization Mechanisms 218
9.3.1.2 Crystallization Temperature and Cooling Rate 218
9.3.1.3 Agitation, Shear and Ultrasound 219
9.3.2 Composition 220
9.3.2.1 Minor Components 220
9.3.2.2 Blending with Different Fats and Oils, and Waxes 220
9.3.3 In a Dispersed State (Emulsion) 221
9.3.3.1 Emulsified State (Cream) vs Bulk State or Anhydrous Milk Fat (AMF) 222
9.3.3.2 Emulsion Droplet Size 222
9.3.3.3 Addition of Emulsifiers 223
9.3.4 In Food Matrices 223
9.3.4.1 Water‐in‐Oil Emulsion 223
9.3.4.2 Foamed Emulsions 224
9.3.4.3 Chocolate 225
9.3.4.4 Cheese 226
9.4 Impact of Resulting Microstructure on the Properties of Different Milk Fat Products 226
9.4.1 Rheology 226
9.4.2 Thermal Stability 229
9.4.3 Sensory Qualities 229
9.5 Conclusions 229
References 230
10 Microstructure of Ice Cream and Frozen Dairy Desserts 237
Samantha R. VanWees and Richard W. Hartel
10.1 Overview of Frozen Desserts 237
10.1.1 Ingredients 238
10.1.2 Processing 239
10.2 Frozen Dessert Structure 240
10.2.1 Serum Phase 240
10.2.2 Ice Crystals 242
10.2.3 Fat Phase 245
10.2.4 Air Cells 247
10.2.5 Proteins and Hydrocolloids 250
10.3 Storage 251
10.3.1 Recrystallization 251
10.3.2 Sugar Crystallization 253
10.3.3 Air Coarsening 254
10.3.4 Shrinkage 255
10.4 Conclusion 256
References 256
11 Whey Wastes and Powders 261
J. Chandrapala
11.1 Whey 261
11.2 Current Whey Uses 263
11.3 Processing of Liquid Whey 263
11.3.1 Recovery of Casein Fines and the Separation of Fat 264
11.3.2 Concentration of Total Solids 265
11.3.3 Drying 266
11.3.4 Fractionation of Total Solids 270
11.4 Whey Powders 274
11.4.1 Whey Protein Concentrates 275
11.4.2 Whey Protein Isolates 277
11.4.3 Whey Protein Hydroxylates 279
11.4.4 Other Whey Powders 280
11.4.4.1 Defatted Whey Protein Concentrates 280
11.4.4.2 Demineralized Whey Protein Concentrates 280
11.4.4.3 Delactosed Whey Powders 283
11.4.4.4 Acid Whey Powders 283
11.4.4.5 Salty Whey Powders 284
11.5 Utilization and Applications of Whey Powders 285
11.6 Conclusion 287
References 287
12 Microstructure of Selected Traditional Indian Dairy Products 293
Bhavbhuti M. Mehta
12.1 Introduction 293
12.2 Heat Desiccated Dairy Products 294
12.2.1 Khoa and Khoa‐Based Sweets 294
12.2.1.1 Microstructure of Khoa 294
12.2.1.2 Microstructure of Gulabjamun 295
12.2.1.3 Microstructure of Burfi and Kalakand 298
12.3 Heat‐Desiccated Milk Cereal Based Desserts 299
12.3.1 Microstructure of Kheer 299
12.4 Heat‐Acid Coagulated Dairy Products 300
12.4.1 Microstructure of Paneer 300
12.4.1.1 Fried Paneer 300
12.4.2 Microstructure of Chhana and Chhana Based Sweets 302
12.4.2.1 Microstructure of Rasogolla 302
12.4.2.2 Microstructure of Chhana Podo 305
12.5 Fermented Dairy Products 306
12.5.1 Microstructure of Dahi 306
12.5.2 Microstructure of Shrikhand 306
12.6 Conclusion 307
References 307
13 Using Microscopy for Microorganism Localization within Dairy Products 311
I.T. Smykov
13.1 Introduction 311
PART 1 312
13.1.1 Microorganisms and Starters 312
13.1.2 Techniques Used in the Microstructure Analyses 313
13.1.3 Interactions Occurring in the Microstructure 315
PART 2 318
13.2 Materials and Methods 318
13.2.1 Bacterial Strains and Dairy Products 318
13.2.2 Electron Microscopy 318
13.2.2.1 Surface Topography Heavy Metal Shadowing 319
13.2.2.2 Negative Staining Transmission Electron Microscopy 319
13.2.3 Freeze‐Fracture Replication 319
13.3 Results and Discussion 320
13.3.1 Casein Micelle 320
13.3.2 Bacteria 324
13.3.3 Bacteria in a Protein Matrix 327
13.3.4 Bacteria in Cheese Eyes 331
13.3.5 Bacteria in Yoghurt 333
13.3.6 Bacteriophages 336
13.4 Conclusions 338
Acknowledgment 339
References 339
14 Microstructure of Dairy Products: Challenges and Future Trends 345
Maricê Nogueira de Oliveira
14.1 Introducing Microstructure of Dairy Products 345
14.2 Microstructure of Fermented Milks 346
14.3 Microstructure of Yogurt and Milk Drinks 347
14.3.1 Yogurt 347
14.3.2 Milk Drinks or Lactic Beverages 354
14.4 Microstructure of Cheeses 356
14.5 Conclusion 359
References 359
Index 363
