Contents Preface XIll General references on dairy chemistry 1 Production and utilization of milk 1. 1 Introduction 1. 3 Classification of mammal 1.4 Structure and development of mammary tissue 111347 1.5 Ultrastructure of the secretory cell 1.6 Techniques used to study milk synthesis 1.6.1 Arteriovenous concentration differences 1.6.3 Perfusion of isolated gland 6.5 Cell homogenates 1. 6.6 Tissue cult 1.8 Production and utilization of milk 1.9 Trade in milk products 0118 References 2 Lacto 21 1 Introduction 2.2 Chemical and physical properties of lactose hesis of lactose 2.2.3 Lactose equilibrium in solution 2.2.4 Significance of mutarotation 2.2.6 Crystallization of lactose .7 Problems related to lactose crystallization Production of actos 2. 4 Derivatives of lactose odification of lactose 43F 2.5 Lactose and the maillard reaction 2.6.1 Lactose intolerance 2.6.2 Galactosaemia
Contents Preface General references on dairy chemistry 1 Production and utilization of milk 1.1 Introduction 1.2 Composition and variability of milk 1.3 Classification of mammals 1.4 Structure and development of mammary tissue 1.5 Ultrastructure of the secretory cell 1.6 Techniques used to study milk synthesis 1.6.1 Arteriovenous concentration differences 1.6.2 Isotope studies 1.6.3 Perfusion of isolated gland 1.6.4 Tissue slices 1.6.5 Cell homogenates 1.6.6 Tissue culture Production and utilization of milk 1.7 Biosynthesis of milk constituents 1.8 1.9 Trade in milk products References Suggested reading 2 Lactose 2.1 2.2 2.3 2.4 2.5 2.6 Introduction Chemical and physical properties of lactose 2.2.1 Structure of lactose 2.2.2 Biosynthesis of lactose 2.2.3 Lactose equilibrium in solution 2.2.4 Significance of mutarotation 2.2.5 Solubility of lactose 2.2.6 Crystallization of lactose 2.2.7 Problems related to lactose crystallization Production of lactose Derivatives of lactose 2.4.1 Enzymatic modification of lactose 2.4.2 Chemical modifications 2.4.3 Fermentation products Lactose and the Maillard reaction Nutritional aspects of lactose 2.6.1 Lactose intolerance 2.6.2 Galactosaemia xiii xv 1 1 1 3 4 7 8 8 9 9 10 10 10 11 11 18 20 20 21 21 23 23 23 25 27 27 28 31 39 42 42 43 50 54 56 58 61
CONTENTS 2.7 Determination of lactose concentration 2.7.2 Oxidation and reduction titration 2.7.3 Colorimetric methods 2.7. 4 Chromatographic methods 2.7.5 Enzymatic methe Referenc Suggested reading 3 Milk lipids 3.1 Introductie Factors that affect the fat content of bovine milk 3.5 Synthesis of fatty acids in milk fat 81 milk lipids 7 Milk fat as an emulsion 8 Milk fat glo lation of the fat globule membrane 3.8.2 Gross chemical composition of FGM 3.8.3 The protein fraction 9449 3.8.5 Other membrane components 8.7 Secretion of milk lipid globules 97 3.9 Stability of the milk fat emulsion 3.9. 1 Emulsion stability in general 3.9.2 The creaming process in milk 3. 10 Influence of processing operations on the fat globule 3.10.4 Heating 116 3. 11 Physical defects in milk and cream 3.11.1 Free fa 3.12 Churning 3. 14 Dehydration 3.15 Lipid oxid 3.15.1 Pro-oxidants in milk and milk products 1122202 3. 15.2 Antioxidants in milk 3. 15.4 Other factors that affect lipid oxidation in milk and 3. 1k.15.5 Meas products 133 3. 16. 1 Fatty acid profile and distribution Suggested reading
vi CONTENTS 3 2.7 Determination of lactose concentration 2.7.1 Polarimetry 2.7.2 Oxidation and reduction titration 2.7.3 Colorimetric methods 2.7.4 Chromatographic methods 2.7.5 Enzymatic methods References Suggested reading Milk lipids 3.1 Introduction 3.1 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.1 1 3.12 3.13 3.14 3.15 3.16 Factors that affect the fat content of bovine milk Classes of lipids in milk Fatty acid profile of milk lipids Synthesis of fatty acids in milk fat Structure of milk lipids Milk fat as an emulsion Milk fat globule membrane 3.8.1 Isolation of the fat globule membrane 3.8.2 Gross chemical compositlion of FGM 3.8.3 The protein fraction 3.8.4 The lipid fraction 3.8.5 Other membrane components 3.8.6 Membrane structure 3.8.7 Secretion of milk lipid globules Stability of the milk fat emulsion 3.9.1 Emulsion stability in general 3.9.2 The creaming process in milk Influence of processing operations on the fat globule membrane 3.10.1 Milk supply: hydrolytic rancidity 3.10.2 Mechanical separation of milk 3.10.3 Homogenization 3.10.4 Heating Physical defects in milk and cream 3.11.1 Free fat Churning Freezing Dehydration Lipid oxidation 3.15.1 3.15.2 Antioxidants in milk 3.15.3 Spontaneous oxidation 3.15.4 Other factors that affect lipid oxidation in milk and dairy products 3.15.5 Measurement of lipid oxidation Rheology of milk fat 3.16.1 3.16.2 Process parameters Pro-oxidants in milk and milk products Fatty acid profile and distribution References Suggested reading Appendices 62 62 63 64 65 65 65 66 67 67 68 71 75 81 87 90 92 93 94 94 95 97 97 100 1 04 104 106 108 108 111 113 116 117 118 118 126 126 127 130 132 133 133 134 134 134 137 140 141 141
CONTENTS 4 Milk proteins 146 4. 1 Introducti 4. 2. 1 Other protei 4.3P proteins 4.3. 1 Acid (isoelecti 4.3.2 Centrifugation 4.3.3 Centrifugation of calcium-supplemented milk 4.3.5 Ultrafiltration 4.3.6 Gel filtration (gel permeation chromatography) 3.7 Precipitation with ethanol 4.3.9 Rennet coagulation 4.3.10 Other methods for the preparation of whey proteins 4.4 Heterogeneity and fractionation of casein 4.1 Resolution of caseins by electropho 4.3 Nomenclature of the e important properties of the caseins 4.5, 4.5.2 and tertiary structures 4.5.4 4.5.5 Influence of Ca on casein 4.5.6 Action of rennets on casein 4.5.8 Casein micelle structure 4.6 Whey proteins 186 paration 186 4.6.2 Heterogenity of whey proteins 4.7B 4.7.1 Occurrence and microheterogeneity 4.7.2 Amino acid composition 4.7.3 Primary structure 4.7.5 Tertiary structure 377P gical function 4.7. 8 Denaturation 4.8 4.8.1 Amino acid composition etic variants 4.8.3 Primary structure 4. 8.4 Secondary and tertiary structure 48.5 ructure 4.8.6 Other specie 4.8.7 ical function binding and heat stability 4.10 Immunoglobulins 4.12 Non-prot In 4.13 Comparison of human and bovine milks 200
CONTENTS vii 4 Milk proteins 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 Introduction Heterogeneity of milk proteins 4.2.1 Other protein fractions Preparation of casein and whey proteins 4.3.1 Acid (isoelectric) precipitation 4.3.2 Centrifugation 4.3.3 Centrifugation of calcium-supplemented milk 4.3.4 Salting-out methods 4.3.5 Ultrafiltration 4.3.6 4.3.7 Precipitation with ethanol 4.3.8 Cryoprecipitation 4.3.9 Rennet coagulation 4.3.10 Other methods for the preparation of whey proteins Heterogeneity and fractionation of casein 4.4.1 4.4.2 Microheterogeneity of the caseins 4.4.3 Nomenclature of the caseins Some important properties of the caseins 4.5.1 Chemical composition 4.5.2 Secondary and tertiary structures 4.5.3 Molecular size 4.5.4 Hydrophobicity 4.5.5 Influence of Ca2+ on caseins 4.5.6 Action of rennets on casein 4.5.7 Casein association 4.5.8 Casein micelle structure Whey proteins 4.6.1 Preparation 4.6.2 Heterogentity of whey proteins P-Lactoglobulin 4.7.1 Occurrence and microheterogeneity 4.7.2 Amino acid composition 4.7.3 Primary structure 4.7.4 Secondary structure 4.7.5 Tertiary structure 4.7.6 Quaternary structure 4.7.7 Physiological function 4.7.8 Denaturation a-Lactal bumin 4.8.1 Amino acid composition 4.8.2 Genetic variants 4.8.3 Primary structure 4.8.4 Secondary and tertiary structure 4.8.5 Quaternary structure 4.8.6 Other species 4.8.7 Biological function 4.8.8 Blood serum albumin Immunoglobulins (Ig) Minor milk proteins Non-protein nitrogen Comparison of human and bovine milks Gel filtration (gel permeation chromatography) Resolution of caseins by electrophoresis Metal binding and heat stability 146 146 149 150 152 152 153 153 153 153 154 154 154 154 155 155 159 160 162 163 163 175 178 178 179 179 180 180 186 186 186 187 188 188 189 189 189 190 191 192 192 192 192 192 193 193 193 194 194 195 195 199 199 200
CONTENTS 4.14 Synthesis and secretion of milk proteins 4.14.2 Amino acid transport into th 4.14.3 Synthesis of milk proteins 14.4 Modifications of the polypeptide chain 14.5 Structi 4.14.7 Secretion of immunoglobulins 4. 15 Functional milk proteins 210 uction of caseins 4. 215 4.15.5 Applications of cas 219 4. 15.7 Casein-whey protein coprecipita 4.16 Biologically active pro 4. 16.2 Lactotransferr 4. 16.5 Growth factors 4. 16.6 Bifidus factors hydrolysates Refer ilk 39 5.2 Method of anal 5.3 Composition of milk salts 5.6 Interrelations of milk salt constituents 5.7 Partition of milk salts between colloidal and soluble phases 5.7.1 Methods used to separate the colloidal and soluble phases 5.7.2 Soluble salts 5.7.3 Measurement of calcium and magnesium ions 7.4 Colloidal 5.8 Changes in milk salts equilibria induced by various treatments 5.8. 1 Addition of acid or alkali 5.8.3 Effect of changes in temperature 5.8.4 Changes in pH induced by temperature 5.8.5 Efect of dilution and concentration R
... Vlll CONTENTS 4.14 Synthesis and secretion of milk proteins 4.14.1 Sources of amino acids 4.14.2 4.14.3 Synthesis of milk proteins 4.14.4 4.14.5 4.14.6 Secretion of milk-specific proteins 4.14.7 Secretion of immunoglobulins 4.15.1 Industrial production of caseins 4.15.2 Novel methods for casein production 4.15.3 Fractionation of casein 4.1 5.4 Functional (physicochemical) properties of caseins 4.15.5 Applications of caseins 4.15.6 Whey proteins 4.15.7 Casein-whey protein co-precipitates Biologically active proteins and peptides in milk 4.16.1 Lactoperoxidase 4.16.2 Lactotransferrin 4.16.3 Immunoglobulins 4.16.4 Vitamin-binding proteins 4.16.5 Growth factors 4.16.6 Bifidus factors 4.16.7 Milk protein hydrolysates Amino acid transport into the mammary cell Modifications of the polypeptide chain Structure and expression of milk protein genes 4.15 Functional milk proteins 4.16 References Suggested reading Appendices 5 Salts of milk 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 Introduction Method of analysis Composition of milk salts Secretion of milk salts Factors influencing variation in salt composition 5.5.1 Breed of cow 5.5.2 Stage of lactation 5.5.3 Infection of the udder 5.5.4 Feed Interrelations of milk salt constituents Partition of milk salts between colloidal and soluble phases 5.7.1 5.7.2 Soluble salts 5.7.3 5.7.4 Colloidal milk salts Changes in milk salts equilibria induced by various treatments 5.8.1 Addition of acid or alkali 5.8.2 Addition of various salts 5.8.3 Effect of changes in temperature 5.8.4 Changes in pH induced by temperature 5.8.5 Etfect of dilution and concentration 5.8.6 Etfect of freezing Methods used to separate the colloidal and soluble phases Measurement of calcium and magnesium ions 20 1 20 1 203 203 205 206 207 209 210 21 1 215 216 218 219 219 227 228 229 229 230 230 23 1 23 1 232 234 236 237 239 239 239 240 242 243 24 3 244 247 247 247 249 249 250 254 256 260 260 26 1 26 1 262 262 263 263 264 References Suggested reading
CONTENTS 6 Vitamins in milk and dairy products 265 6.1 Introductie 265 6.2 Fat-soluble vitamins 2.1 Retinol (vitamin A) 6.2.3 Tocopherols and related compounds(vitamin E) 6.2.4 Phylloquinone and related compounds ( vitamin K) 275 6.3.2 Riboflavin(vitami 6.3.3 Niac 63,4 63.5 6.3.8 Cobalamin and its derivatives(vitamin B12) 6.4 Ascorbic acid (vitamin C) rences Suggested reading 291 7 Water in milk and dairy products 294 7.1 Introduction 7.2 General properties of water 7.4 Water sorption 5 Glass transition and the role of water in plasticization 7.6 Non-equilibrium ice formation 7.7 Role of water in stickiness and caking of powders and 313 7.8 Water and the stability of dairy products 316 Suggested reading 316 8 Enzymology of milk and milk products 317 8. 1 Introduc 8.2.2 Proteinases(EC 3.4, . 8.2.3 Lipases and esterases(EC 3.1.1.) ozyme(EC 3. 2.1. 17) 327 8.2.6 N-Acetyl-B-D-glucosaminidase(EC 3.2.1.30 8.2.7 7-Glutamyl transpeptidase( transferase)(EC 2.3.2.2 8.2.8 Xanthine oxidase(EC 1.2.3.2 8.2.9 Sulphydryl oxidase (EC 1.8.3. -) 2.10 Superoxide dismutase(EC 1. 15.1.1) 8.2. 11 Catalase(EC 1. 11.1.6) 331 8.2.12 Lactoperoxidase(EC 1.11.1.7) 8.2, 13 Other enzymes
CONTENTS ix 6 Vitamins in milk and dairy products 6.1 Introduction 6.2 Fat-soluble vitamins 6.2.1 Retinol (vitamin A) 6.2.2 Calciferols (vitamin D) 6.2.3 Tocopherols and related compounds (vitamin E) 6.2.4 Phylloquinone and related compounds (vitamin K) 6.3.1 Thiamin (vitamin B,) 6.3.2 Riboflavin (vitamin B2) 6.3.3 Niacin 6.3.4 Biotin 6.3.5 Panthothenic acid 6.3.6 6.3.7 Folate 6.3.8 6.3 B-group vitamins Pyridoxine and related compounds (vitamin B6) Cobalamin and its derivatives (vitamin B12) 6.4 Ascorbic acid (vitamin C) References Suggested reading Appendices 7 Water in milk and dairy products 7.1 Introduction 7.2 General properties of water 7.3 Water activity 7.4 Water sorption 7.5 Glass transition and the role of water in plasticization 7.6 Non-equilibrium ice formation 7.7 Role of water in stickiness and caking of powders and crystallization of lactose 7.8 Water and the stability of dairy products References Suggested reading 8 Enzymology of milk and milk products 8.1 Introduction 8.2 Indigenous enzymes of bovine milk 8.2.1 Introduction 8.2.2 Proteinases (EC 3.4~) 8.2.3 8.2.4 Phosphatases 8.2.5 Lysozyme (EC 3.2.1.17) 8.2.6 N-Acetyl-P-D-glucosaminidase (EC 3.2.1.30) 8.2.7 8.2.8 Xanthine oxidase (EC 1.2.3.2) 8.2.9 Sulphydryl oxidase (EC 1.8.3.-) 8.2.10 Superoxide dismutase (EC 1.15.1.1) 8.2.11 Catalase (EC 1.11.1.6) 8.2.12 Lactoperoxidase (EC 1.1 1.1.7) 8.2.13 Other enzymes Lipases and esterases (EC 3.1.1.-) y-Glutamyl transpeptidase (transferase) (EC 2.3.2.2) 265 265 266 266 269 272 274 275 275 277 279 28 1 281 282 285 287 289 291 29 1 29 1 294 294 294 301 305 311 312 313 313 316 316 317 317 317 317 318 322 324 327 328 328 328 330 330 331 331 333