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
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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
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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
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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
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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
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References
Suggested reading
CONTENTS
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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)
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8.3 Exogenous enzymes in dairy technology
8.3.1 Introduction
8.3.2 Proteinases
8.3.3 P-Galactosidase
8.3.4 Lipases
8.3.5 Lysozyme
8.3.6 Catalase
8.3.7 Glucose oxidase
8.3.8 Superoxide dismutase
8.3.9 Exogeneous enzymes in food analysis
References
Suggested reading
9 Heat-induced changes in milk
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.8
9.9
9.10
Introduction
Lipids
9.2.1 Physiochemical changes
9.2.2 Chemical changes
Lactose
9.3.1 Formation of lactulose
9.3.2 Formation of acids
9.3.3 Maillard browning
Milk salts
Vitamins
Proteins
9.6.1 Enzymes
9.6.2 Denaturation of other biologically active proteins
9.6.3 Denaturation of whey proteins
9.6.4 Effect of heat on caseins
Heat stability of milk
9.7.1 Effect of processing operations on heat stability
Effect of heat treatment on rennet coagulation of milk
and related properties
Age gelation of sterilized milk
Heat-induced changes in flavour of milk
References
Suggested reading
10 Chemistr and biochemistry of cheese and
fermente B milks
10.1 Introduction
10.2 Rennet-coagulated cheeses
10.2.1 Preparation and treatment of cheesemilk
10.2.2 Conversion of milk to cheese curd
10.2.3 Acidification
10.2.4 Moulding and shaping
10.2.5 Salting
10.2.6 Manufacturing protocols for some cheese varieties
10.2.7 Cheese ripening
10.2.8 Cheese flavour
10.2.9 Accelerated ripening of cheese
10.3 Acid-coagulated cheeses
10.4 Processed cheese products
10.4.1 Processing protocol
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10.5 Cheese analogues
10.6 Cultured milks
References
Suggested reading
Appendices
11 Physical properties of milk
11.1 Ionic strength
11.2 Density
11.3 Redox properties of milk
11.4 Colligative properties of milk
11.5 Interfacial tension
11.6 Acid-base equilibria
11.7 Rheological properties
11.7.1 Newtonian behaviour
11.7.2 Non-Newtonian behaviour
11.7.3 Rheology of milk gels
11.7.4 Rheological properties of milk fat
11.8 Electrical conductivity
11.9 Thermal properties of milk
11.10
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References
Suggested reading
Interaction of light with milk and dairy products
Colour of milk and milk products
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