Microstructure of Dairy Products

Mamdouh Mahmoud Abdel-Rahman El-Bakry is a Postdoctoral Researcher in the Department of Chemical Engineering at the Universitat Autònoma of Barcelona, Spain. Antoni Sanchez is a Professor in the Department of Chemical Engineering at the Universitat Autònoma of Barcelona, Spain. Bhavbhuti M. Mehta is an Associate Professor in the Dairy Chemistry Department, SMC College of Dairy Science, Anand Agricultural University, Gujarat, India.

• List of Contributors xiiiPreface xv1 Microscopy Techniques for Dairy Products – An Introduction 1Mark A.E. Auty1.1 Introduction 11.1.1 Brief History and Background 11.2 Conventional Optical Microscopy Techniques 41.2.1 Conventional Light Microscopy – Optical Contrast 41.2.1.1 Bright Field 41.2.1.2 Polarized Light 41.2.1.3 Phase Contrast 41.2.1.4 Differential Interference Contrast 51.2.1.5 Fluorescence 51.2.2 Chemical Contrast Techniques in Light Microscopy 51.3 Confocal Scanning Laser Microscopy 61.3.1 Confocal Principle 61.3.2 Identifying Dairy Primary Components in CSLM: Labeling Strategies 81.3.2.1 Generic Labeling 81.3.2.2 Specific Labeling 101.3.2.3 Covalent Labeling 111.3.3 Some Applications of Confocal Microscopy to Dairy Products and Ingredients 121.3.3.1 Spreads 121.3.3.2 Emulsions and Foams 121.3.3.3 Fermented Milks 121.3.3.4 Cheese 131.3.3.5 Dairy Powders 131.3.3.6 Milk Protein Gel Systems 141.3.3.7 Dynamic CSLM Techniques 141.4 Electron Microscopy (EM) Techniques 161.4.1 Transmission Electron Microscopy 161.4.2 Scanning Electron Microscopy 181.4.3 Other EM Techniques 181.4.3.1 X‐ray Microanalysis 181.4.3.2 Cryo‐electron Microscopy 191.4.3.3 Environmental and Variable Pressure SEM 201.5 Emerging Microscopy Techniques 201.5.1 Atomic Force Microscopy 201.5.2 Advanced Fluorescence Microscopy Techniques 221.5.3 Confocal Raman Microscopy 221.5.4 X‐ray Nano/Microtomography 221.5.5 Super‐Resolution Microscopy 231.6 Image Analysis 231.7 Conclusions 24References 242 Light Microscopy and CSLM Techniques, Principles and Applications 33Johan Hazekamp2.1 Introduction 332.1.1 The History of Microscopy 332.1.2 Evolution of Confocal Microscopy 342.1.3 Food Microscopy 352.1.4 Wide Field Microscopy 362.1.5 Confocal Scanning Laser Microscopy (CSLM) 382.2 Sample Preparation and Specific Staining and Labeling 412.2.1 Specific Labeling 442.2.2 Dynamic Imaging 462.2.3 Future Perspectives 46References 473 Electron Microscopy Techniques 51Semih Otles and Vasfiye Hazal Ozyurt3.1 Introduction 513.2 Types of EM 513.2.1 Scanning Electron Microscopy (SEM) 513.2.2 Transmission Electron Microscopy (TEM) 523.2.3 Cryo‐SEM 523.2.4 Cryo‐TEM 533.2.5 Environmental Scanning Electron Microscopy (ESEM) 533.3 Sample Preparation for EMs 533.3.1 Scanning Electron Microscopy 533.3.2 Transmission Electron Microscopy 533.3.3 Cryo‐Scanning Electron Microscopy 533.4 Dairy Microstructure 543.5 Electron Microscopy for the Dairy Product 543.6 Summary 60References 644 Emerging Techniques for Microstructural Analysis 67I. Hernando, E. Llorca, and A. Quiles4.1 Introduction 674.2 Scanning Probe Microscopy 674.2.1 Scanning Tunneling Microscope (STM) 694.2.2 Atomic Force Microscope (AFM) 704.2.3 Applications of the Main Probe Microscopes 714.3 X‐Ray Tomography 724.4 Small‐Angle‐Scattering (SAS) Methods: SAXS and SANS 744.4.1 Small‐Angle X‐Ray Scattering (SAXS) 744.4.2 Small‐Angle Neutron Scattering (SANS) 754.4.3 Applications of Small‐Angle‐Scattering Methods 754.5 Vibrational Spectroscopies (Fourier Transform Infrared‐FTIR and Raman Microscopy) 754.5.1 Fourier Transform Infrared (FTIR) Spectroscopy 764.5.2 Raman Spectroscopy 784.6 Magnetic Resonance: NMR and MRI 804.7 Conclusions 82References 825 Quantitative Image Analysis in Microscopy 89Gaetano Impoco5.1 Aim and Scope 895.2 Image Analysis Software 905.3 Applications to Microscopy for Dairy Science 975.3.1 Porosity 985.3.2 Fat Globules 995.3.3 Microbial Cells 1005.4 Image Analysis and Quantitative Measurement 1005.4.1 Image Analysis Basics 1015.4.1.1 Feature Detection 1025.4.1.2 Quantitative Analysis 1035.4.2 Common Pitfalls 1055.4.3 Misuse and Wrong Interpretation of Image Analysis Results 1145.4.4 Good Practices 1165.4.5 Image Analysis in your Lab 1195.5 Conclusions 122Acknowledgments 123References 1236 Microstructure of Milk 127Michael H. Tunick6.1 Components of Milk 1276.2 Fat 1276.2.1 Fat Globules 1276.2.2 Milkfat Globule Membrane 1286.2.3 Cream 1296.3 Protein 1336.3.1 Types of Protein 1336.3.2 Casein Micelles in Bovine Milk 1336.3.3 Casein Micelles in Caprine Milk 1336.3.4 Casein Micelles in Milk of Other Species 1366.3.5 Micelle Structure 1366.4 Bacteria and Somatic Cells 1376.5 Concentrated Milk 1386.6 Digested Milk 1406.7 Conclusion 142Acknowledgments 142References 1427 Microstructure of Cheese Products 145Bhavbhuti M. Mehta7.1 Introduction 1457.2 Factors Affecting the Development of Microstructures in Cheeses 1467.2.1 Addition of Calcium Chloride 1487.2.2 Rennet Coagulation 1497.2.3 Acid‐Coagulation 1507.2.4 Coagulation Temperature 1507.2.5 Syneresis 1517.2.6 Salting 1517.2.7 Ripening 1527.2.8 Homogenization and High Pressure Treatments 1537.2.9 Evaporation and Ultrafiltration Treatments 1557.2.10 Freezing 1567.2.11 Fat Replacers 1567.3 Microstructures of Various Components in Cheese Matrix 1587.3.1 Protein in Cheese Matrix 1587.3.2 Fat Globule in Cheese Matrix 1597.3.3 Calcium in Cheese Matrix 1627.4 Crystals in Cheese Matrix 1627.5 Starter Bacteria in Cheese Matrix 1637.6 Microstructure of Selected Varieties of Cheeses 1647.6.1 Processed Cheese 1647.6.1.1 Curd Granules and Fat 1667.6.1.2 Occurrence of Crystals 1667.6.2 Cheese Analogs 1667.6.3 Feta Cheese 1677.6.4 Domiati Cheese 1677.6.5 Fresh Cheese 1677.6.6 Cream Cheese 1687.6.7 Mold‐Ripened Cheeses 1697.6.8 Cheese Powder 1697.7 Cheese Matrix and Digestion 1707.8 Conclusions 171References 1718 Microstructural Aspects of Yogurt and Fermented Milk 181P.H.P. Prasanna, C.S. Ranadheera, and J.K. Vidanarachchi8.1 Yogurt and Fermented Milk: An Overview 1818.2 Yogurt and Fermented Milk: Production Technologies 1848.3 Microstructure of Yogurt and Fermented Milk 1878.4 Factors Influencing Microstructure of Yogurt and Fermented Milk 1888.4.1 Effects of Type of Milk on Structure 1888.4.2 Rate of Inoculation Level and Starter Culture Composition on Microstructure of Yogurt and Fermented Milk 1898.4.2.1 Rate of Inoculation 1898.4.2.2 Culture Composition 1898.4.3 Effect of Exopolysaccharide Producing Starter Culture on Microstructure 1908.4.4 Incubation Temperature on Structure 1918.4.5 Effect of Different Processing Steps 1918.4.5.1 Homogenization of Milk 1918.4.5.2 Heat Treatment of Milk 1928.4.5.3 Effect of Stirring 1928.4.6 Effect of Addition of Different Hydrocolloids and Fibers on Microstructure 1938.5 Microscopy Methods Used for Analyzing Microstructure of Fermented Milk 1948.5.1 Light Microscopy 1948.5.1.1 Bright Field Light Microscopy 1948.5.1.2 Polarized Light Microscopy 1948.5.1.3 Fluorescence Microscopy 1958.5.1.4 Confocal Laser Scanning Microscopy 1978.5.2 Electron Microscopy 1988.5.2.1 Scanning Electron Microscopy 1988.5.2.2 Transmission Electron Microscopy 2008.6 Conclusions 201References 2029 Microstructure of Milk Fat and its Products 209Pere Randy R. Ramel and Alejandro G. Marangoni9.1 Introduction 2099.2 Milk Fat Crystal Structure 2119.2.1 Mesoscale Structure of Milk Fat 2119.2.1.1 Polymorphism 2119.2.1.2 Phase Behavior and Fractionation 2139.2.1.3 Solid Fat Content and Crystallization/Melting Behavior 2149.2.2 Nanoscale Structure of Fat Crystal Networks 2169.3 Effect of Different Factors on the Crystallization Behavior and Microstructure of Milk Fat 2189.3.1 Processing Conditions 2189.3.1.1 Different Crystallization Mechanisms 2189.3.1.2 Crystallization Temperature and Cooling Rate 2189.3.1.3 Agitation, Shear and Ultrasound 2199.3.2 Composition 2209.3.2.1 Minor Components 2209.3.2.2 Blending with Different Fats and Oils, and Waxes 2209.3.3 In a Dispersed State (Emulsion) 2219.3.3.1 Emulsified State (Cream) vs Bulk State or Anhydrous Milk Fat (AMF) 2229.3.3.2 Emulsion Droplet Size 2229.3.3.3 Addition of Emulsifiers 2239.3.4 In Food Matrices 2239.3.4.1 Water‐in‐Oil Emulsion 2239.3.4.2 Foamed Emulsions 2249.3.4.3 Chocolate 2259.3.4.4 Cheese 2269.4 Impact of Resulting Microstructure on the Properties of Different Milk Fat Products 2269.4.1 Rheology 2269.4.2 Thermal Stability 2299.4.3 Sensory Qualities 2299.5 Conclusions 229References 23010 Microstructure of Ice Cream and Frozen Dairy Desserts 237Samantha R. VanWees and Richard W. Hartel10.1 Overview of Frozen Desserts 23710.1.1 Ingredients 23810.1.2 Processing 23910.2 Frozen Dessert Structure 24010.2.1 Serum Phase 24010.2.2 Ice Crystals 24210.2.3 Fat Phase 24510.2.4 Air Cells 24710.2.5 Proteins and Hydrocolloids 25010.3 Storage 25110.3.1 Recrystallization 25110.3.2 Sugar Crystallization 25310.3.3 Air Coarsening 25410.3.4 Shrinkage 25510.4 Conclusion 256References 25611 Whey Wastes and Powders 261J. Chandrapala11.1 Whey 26111.2 Current Whey Uses 26311.3 Processing of Liquid Whey 26311.3.1 Recovery of Casein Fines and the Separation of Fat 26411.3.2 Concentration of Total Solids 26511.3.3 Drying 26611.3.4 Fractionation of Total Solids 27011.4 Whey Powders 27411.4.1 Whey Protein Concentrates 27511.4.2 Whey Protein Isolates 27711.4.3 Whey Protein Hydroxylates 27911.4.4 Other Whey Powders 28011.4.4.1 Defatted Whey Protein Concentrates 28011.4.4.2 Demineralized Whey Protein Concentrates 28011.4.4.3 Delactosed Whey Powders 28311.4.4.4 Acid Whey Powders 28311.4.4.5 Salty Whey Powders 28411.5 Utilization and Applications of Whey Powders 28511.6 Conclusion 287References 28712 Microstructure of Selected Traditional Indian Dairy Products 293Bhavbhuti M. Mehta12.1 Introduction 29312.2 Heat Desiccated Dairy Products 29412.2.1 Khoa and Khoa‐Based Sweets 29412.2.1.1 Microstructure of Khoa 29412.2.1.2 Microstructure of Gulabjamun 29512.2.1.3 Microstructure of Burfi and Kalakand 29812.3 Heat‐Desiccated Milk Cereal Based Desserts 29912.3.1 Microstructure of Kheer 29912.4 Heat‐Acid Coagulated Dairy Products 30012.4.1 Microstructure of Paneer 30012.4.1.1 Fried Paneer 30012.4.2 Microstructure of Chhana and Chhana Based Sweets 30212.4.2.1 Microstructure of Rasogolla 30212.4.2.2 Microstructure of Chhana Podo 30512.5 Fermented Dairy Products 30612.5.1 Microstructure of Dahi 30612.5.2 Microstructure of Shrikhand 30612.6 Conclusion 307References 30713 Using Microscopy for Microorganism Localization within Dairy Products 311I.T. Smykov13.1 Introduction 311PART 1 31213.1.1 Microorganisms and Starters 31213.1.2 Techniques Used in the Microstructure Analyses 31313.1.3 Interactions Occurring in the Microstructure 315PART 2 31813.2 Materials and Methods 31813.2.1 Bacterial Strains and Dairy Products 31813.2.2 Electron Microscopy 31813.2.2.1 Surface Topography Heavy Metal Shadowing 31913.2.2.2 Negative Staining Transmission Electron Microscopy 31913.2.3 Freeze‐Fracture Replication 31913.3 Results and Discussion 32013.3.1 Casein Micelle 32013.3.2 Bacteria 32413.3.3 Bacteria in a Protein Matrix 32713.3.4 Bacteria in Cheese Eyes 33113.3.5 Bacteria in Yoghurt 33313.3.6 Bacteriophages 33613.4 Conclusions 338Acknowledgment 339References 33914 Microstructure of Dairy Products: Challenges and Future Trends 345Maricê Nogueira de Oliveira14.1 Introducing Microstructure of Dairy Products 34514.2 Microstructure of Fermented Milks 34614.3 Microstructure of Yogurt and Milk Drinks 34714.3.1 Yogurt 34714.3.2 Milk Drinks or Lactic Beverages 35414.4 Microstructure of Cheeses 35614.5 Conclusion 359References 359Index 363