Microstructure of dairy products

423 Pages·2018·31.32 MB·English

by  El-Bakry

Microstructure of Dairy Products

Microstructure of Dairy Products
First Edition
Edited by
Mamdouh Mahmoud Abdel‐Rahman El‐Bakry
Universitat Autònoma of Barcelona
Barcelona, Spain
Antoni Sanchez
Universitat Autònoma of Barcelona
Barcelona, Spain
Bhavbhuti M. Mehta
Anand Agricultural University
Gujarat, India
This edition first published 2018
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v
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
vi Contents
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
Contents vii
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
viii Contents
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