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Advanced Dairy Chemistry, Volume 3, Lactose, Salts, Water and Minor Constituents Springer, New York, pp 203–229 Keenan TW, Mather IH 2003 Milk fat globule membrane In: H Roginski et al (eds.) Encyclopedia of Dairy Science Academic Press, London, pp 1568–1576 Kelly ML et al 1998 Dietary fatty acid content significantly affects conjugated linoleic acid concentrations in milk from lactating dairy cows J Nutr 128: 881–885 Kelly AL et al 2003 Manufacture and properties of milk powders In: PF Fox, PLH McSweeney (eds.) Advanced Dairy Chemistry, Volume 1, Proteins Kluwer Academic-Plenum Publishers, New York, pp 1027–1062 Keenan TW, Mather IH 2006 Intercellular origin of milk fat globules and the nature of the milk fat globule membrane In: PF Fox, PLH McSweeney (eds.) Advanced Dairy Chemistry, Volume 1, Lipids Springer, New York, pp 137–171 Keogh MK et al 1982 Studies of milk composition and its relationship to some processing criteria I Seasonal variation in the mineral levels in milk Ir J Food Sci Tech 6: 13–27 Korhonen H, Marnila P 2011 Lactoferrin In: Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 801–806 Kraft J et al 2000 Duodenal infusion of conjugated linoleic acid mixture influences milk fat synthesis and milk conjugated linoleic acid content In: Milk Composition British Society of Animal Science Occasional Publication No 25, pp 143–147 Lawless F et al 2000 Dietary effect on bovine milk fat conjugated linoleic acid content In: Milk Composition British Society of Animal Science Occasional Publication No 25, pp 283–293 Lefebvre-Cases E et al 2001a Effect of SDS on casein micelles: SDS-induced milk gel formation Journal of Food Science 66: 38–42 Lefebvre-Cases E et al 2001b Effect of SDS on acid milk coagulability J Food Sci 66: 555–560 Lock AL, Garnsworthy PC 2000 Independent effects of dietary linoleic and linolenic fatty acids on the conjugated linoleic acid content of cow’s milk J Anim Sci 74: 163–176 Lonnerdal B 2003 Lactoferrin In: PF Fox, PLH McSweeney (eds.) Advanced Dairy Chemistry, Volume 1, Proteins Kluwer Academic-Plenum Publishers, New York, pp 449–466 Lucey JA, Horne DS 2009 Milk salts: technological significance In: PLH McSweeney, PF Fox (eds.) Advanced Dairy Chemistry, Volume 3, Lactose, Salts, Water and Minor Constituents Springer, New York, pp 351–389 P1: SFK/UKS BLBS102-c24 P2: SFK BLBS102-Simpson March 21, 2012 13:47 Trim: 276mm X 219mm Printer Name: Yet to Come 24 Chemistry and Biochemistry of Milk Constituents Marnila P, Korhonen H 2011 Immunoglobulins In: J Fuquay et al (eds.) Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 807–815 Martin P et al 2003 Non-bovine caseins: Quantitive variability and molecular diversity In: PF Fox, PLH McSweeney (eds.) Advanced Dairy Chemistry, Volume 1, Proteins Kluwer AcademicPlenum Publishers, New York, pp 277–317 Martin P et al 2011 Interspecies comparison of milk proteins: Quantitative variability and molecular diversity In: J Fuquay et al (eds.) Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 821–842 Mather IH 2000 A revised and proposed nomenclature for major proteins of the milk fat globule membrane J Dairy Sci 83: 203–247 Mather I 2011 Milk fat globule membrane In: J Fuquay et al (eds.) Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 680–690 McSweeney PLH, Fox PF (eds.) 2009 Advanced Dairy Chemistry, Volume 3, Lactose, Water, Salts and Minor Constituents, 3rd edn Springer, New York Mehra R et al 1999 Seasonal variation in the composition of Irish manufacturing and retail milk Nitrogen fractions Ir J Agr Food Res 38: 65–74 Meesapyodsuk D et al 2000 Substrate specificity, regioselectivity and cryptoregiochemistry of plant and animal omega-3-fatty acid desaturases Biochem Soc Trans 28: 632–635 Morr CV 1967 Effect of oxalate and urea upon ultracentrifugation properties of raw and heated skim milk casein micelles J Dairy Sci 50: 1744–1751 Nursten H 2011 Maillard reactions In: J Fuquay et al (eds.) Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 217–235 O’Brien J 2009 Non-enzymatic degradation pathways of lactose and their significance in dairy products In: PLH McSweeney, PF Fox (eds.) Advanced Dairy Chemistry, Volume 3, Lactose, Water, Salts and Minor Constituents, 3rd edn Springer, New York, pp 231–294 O’Brien NM, O’Connor TP 2011 Lipid oxidation In: J Fuquay et al (eds.) Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 716–720 O’Brien B et al 1999a Seasonal variation in the composition of Irish manufacturing and retail milk Chemical composition and renneting properties Ir J Agr Food Res 38: 53–64 O’Brien B et al 1999b Seasonal variation in the composition of Irish manufacturing and retail milk Vitamins Ir J Agr Food Res 38: 75–85 O’Brien B et al 1999c Seasonal variation in the composition of Irish manufacturing and retail milk Minerals and trace elements Ir J Agr Food Res 38: 87–99 O’Connell JE et al 2001a Ethanol-dependent heat-induced dissociation of casein micelles Ir J Agr Food Chem 49: 4420– 4423 O’Connell JE et al 2001b Mechanism for the ethanol-dependent heat-induced dissociation of casein micelles J Agri Food Chem 49: 4424–4428 O’Keeffe AM 1984 Seasonal and lactational influences on moisture content of Cheddar cheese Ir J Food Sci Tech 8: 27–37 Paakanen R, Aalto J 1997 Growth factors and antimicrobial factors of bovine colostrums Int Dairy J 7: 285–297 463 Park YW, Haenlein FW (eds.) 2006 Handbook of Non-bovine Mammals Blackwell Publishing, Oxford Parodi PW 1997 Cows’ milk fat components as potential anticarcinogenic agents J Nutr 127: 1055–1060 Parodi PW 1999 Conjugated linoleic acid and other anticarcinogenic agents in bovine milk fat J Dairy Sci 82: 1399–1349 Parodi P 2009 Has the association between saturated fatty acids, serum cholesterol and coronary heart disease been overemphasised? Int Dairy J 19: 345–361 Paterson AHJ 2009 Production and uses of lactose In: PLH McSweeney, PF Fox (eds.) Advanced Dairy Chemistry, Volume 3, Lactose, Water, Salts and Minor Constituents, 3rd edn Springer, New York, pp 105–120 Patterson AHJ 2011 Lactose: Production and applications reactions In: J Fuquay et al (eds.) Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 196–201 Patton S et al 1997 Prosaposin, a neurotrophic factor: presence and properties in milk J Dairy Sci 80: 264–272 Pihlanto-Leppala A 2011 Bioactive peptides In: J Fuquay et al (eds.) Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 879–886 Playne MJ, Crittenden RG 2009 Galacto-oligosaccharides and other products derived from lactose In: PLH McSweeney, PF Fox (eds.) 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Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 241–273 Visser H 1992 A new casein micelle model and its consequences for pH and temperature effects on the properties of milk In: H Visser (ed.) Protein Interactions VCH Publishing, Weinheim, pp 135–165 Walstra P, Jenness R 1984 Dairy Chemistry and Physics John Wiley & Sons, New York Walstra P et al 1999 Dairy Technology: Principles of Milk Properties and Processing Marcel Dekker, New York Walstra P et al 2005 Dairy Science and Technology, 2nd edn CRC Press, Boca Raton, FL Waugh DF, von Hippel PH 1956 κ-Casein and the stabilisation of casein micelles J Am Chem Soc 78: 4576–4582 White JCD, Davies DT 1958 The relationship between the chemical composition of milk and the stability of the caseinate complex I General introduction, description of samples, methods and chemical composition of samples J Dairy Res 25: 236–255 P1: SFK/UKS BLBS102-c24 P2: SFK BLBS102-Simpson 464 March 21, 2012 13:47 Trim: 276mm X 219mm Printer Name: Yet to Come Part 4: Milk Wilson WE et al 1989 Bradykinin and kininogens in bovine milk J Biol Chem 264: 17777–17783 Wong NP et al 1988 Fundamentals of Dairy Chemistry Van Nostrand Reinhold Co., New York Wooten L et al 1996 Ceruloplasmin is found in milk and amniotic fluid and may have a nutritional role J Nutr Biochem 7: 632–639 Wynn P 2011 Minor proteins bovine serum albumin and vitaminbinding proteins In: J Fuquay, PF Fox, PLH McSweeney (eds.) Encyclopedia of Dairy Sciences, 2nd edn Elsevier, Oxford, pp 795–800 Yurawecz MP et al 1999 Advances in Conjugated Linoleic Acid Research American Oil Chemists Society, Minneapolis, MN P1: SFK/UKS BLBS102-c25 P2: SFK BLBS102-Simpson March 21, 2012 13:23 Trim: 276mm X 219mm Printer Name: Yet to Come 25 Biochemistry of Milk Processing A.L Kelly and P.F Fox Introduction Thermal Processing of Milk Introduction Heat-Induced Changes in Milk Proteins Stability of UHT Milk on Storage Heat-Induced Changes in Lactose in Milk and the Maillard Reaction Heat-Induced Changes in Milk Lipids Inactivation of Enzymes on Heating of Milk Changes on Evaporation and Drying of Milk Concentration of Milk Spray-Drying of Milk Freezing of Milk Cheese and Fermented Milks Introduction Rennet-Coagulated Cheeses Coagulation Acidification Post-Coagulation Operations Ripening Glycloysis and Related Events Lipolysis Proteolysis Acceleration of Cheese Ripening Cheese-Related Products Acid-Coagulated Cheeses Fermented Milks Acid-Heat Coagulated Cheeses Whey Processing Range of Whey Products Whey-Protein-Rich Products Lactose Processing Caseins: Isolation, Fractionation and Applications Recovery and Application of Caseins Exogenous Enzymes in Dairy Processing Proteinases β-Galactosidase Transglutaminase Lipases Other Enzymes Milk Lipids Production of Fat-Based Dairy Products Production and Fractionation of Milk Fat Lipid Oxidation Ice Cream Protein Hydrolysates Chocolate Infant Formulae Novel Technologies for Processing Milk and Dairy Products Conclusion and Summary References Abstract: Milk is subjected to a wide range of processes before consumption directly or in the form of the very wide range of modern dairy products Primary objectives of processing involve rendering milk microbiologically safe or stable (e.g., pasteurisation, ultra-high temperature (UHT) milk), isolation of valuable components (e.g., whey proteins, caseins) and conversion to other forms (e.g., cheese, yoghurt, enzymatic hydrolysates) All such processes applied to milk have very significant effects on the properties and distribution of food constituents The principal families of dairy products, which may be produced from milk, and their principles of production, are described in this chapter INTRODUCTION As described in Chapter 24, milk is a very complex system; the continuous phase is an aqueous solution of a specific sugar, lactose, globular (whey/serum) proteins, inorganic salts and hundreds of minor constituents, for example vitamins, at trace levels Dispersed in the aqueous phase as an oil-in-water (o/w) emulsion are lipids in the form of small globules and a second, unique group of proteins, the caseins, which exist as large colloidal Food Biochemistry and Food Processing, Second Edition Edited by Benjamin K Simpson, Leo M.L Nollet, Fidel Toldr´a, Soottawat Benjakul, Gopinadhan Paliyath and Y.H Hui C 2012 John Wiley & Sons, Inc Published 2012 by John Wiley & Sons, Inc 465 P1: SFK/UKS BLBS102-c25 P2: SFK BLBS102-Simpson March 21, 2012 13:23 Trim: 276mm X 219mm 466 Printer Name: Yet to Come Part 4: Milk particles known as casein micelles, with an average diameter of approximately 150 nm (range 50–600 nm) and containing, on average, approximately 5000 protein molecules Owing to its physical state, milk is an unstable system The fat globules, which are less dense than the aqueous phase, rise to the surface where they form a cream layer The fat-rich cream can be skimmed off and used for the manufacture of butter, butter oil, ghee or other fat-rich products Alternatively, the fatdepleted lower layer (skimmed milk) may be run off, for example through a valve at the bottom of a separating vat The skimmed milk may be consumed directly as a beverage or used for the manufacture of a wide range of products Gravity creaming and butter manufacture have been used since prehistoric times, but gravity creaming has been largely replaced by centrifugal separation of the fat since the development of the cream separator by Gustav de Laval in 1878 Gravity separation is still used to prepare reduced-fat milk for the manufacture of ParmigianoReggiano cheese The physics of fat separation by gravity or centrifugal separation and the process of demulsifying milk fat to butter or butter oil will be described briefly later in this chapter Creaming (fat separation) is undesirable in many dairy products (e.g., liquid/beverage milk, concentrated milks) and is prevented by a process known as homogenisation (the commonly used valve homogeniser was developed by Auguste Gaulin in 1899) Homogenisation prevents creaming by reducing the size of the fat globules and preventing their agglomeration (cluster- ing), by denaturing a particular minor protein known as cryoglobulin (type M immunoglobulin) The casein micelles are physicochemically stable but can be destabilised by a number of processes/treatments, which are exploited for the production of new dairy products The most important of these are limited proteolysis and acidification, which are used in the production of cheese, fermented milks and functional milk proteins The mechanism and consequences of proteolysis and acidification will be described briefly Thus, the three main constituents/phases of milk, that is fat, casein and the aqueous solution (whey), can be separated easily Milk is remarkably heat stable; it can be sterilised by heat in standard or concentrated form, or dried to produce a wide range of dairy products The principal processes and the resulting product families are summarised in Table 25.1 All these families of dairy products contain many products, for example approximately 1400 varieties of cheese are produced worldwide In addition to the above considerations, milk is a rich medium for the growth of a wide range of microorganisms While this is exploited in the production of a range of fermented dairy products, it also means that milk can harbour microorganisms that may cause spoilage of products, or present health risks to the consumer Largely for the latter reason, very little raw milk is now consumed, the vast majority being heat treated sufficiently severe to kill all pathogenic and food-poisoning bacteria Table 25.1 Diversity of Dairy Products Produced by Different Processes Process Heat treatment (generally with homogenisation) Centrifugal separation Concentration (e.g., evaporation or membrane separation) Concentration and drying Enzymatic coagulation Acid coagulation Fermentation Freezing, aeration and whipping Source: Adapted From Fox and McSweeney 1998 UHT, ultra-high temperature Primary (italic) and Secondary Products Market milk Standardised milk Cream Butter, butter oil, ghee Creams of various fat content (pasteurised or UHT treated); whipping, coffee, dessert creams Skim milk Skim milk powder, casein, cheese, protein concentrates In-container or UHT-sterilised concentrated milks, sweetened condensed milk Whole milk powders, infant formulae Cheese Numerous varieties, processed cheese, cheese sauces and dips Rennet casein; cheese analogues Whey Whey powders; demineralised whey powders; whey protein concentrates; fractionated whey proteins; whey protein hydrolysates; lactose and lactose derivatives Cheese (fresh) Acid casein; functional proteins Whey (as rennet whey) Various fermented milk products, e.g., yoghurt, buttermilk, acidophilus milk, bioyoghurt Ice cream ... Vitamins Ir J Agr Food Res 38: 75? ?85 O’Brien B et al 1999c Seasonal variation in the composition of Irish manufacturing and retail milk Minerals and trace elements Ir J Agr Food Res 38: 87 –99 O’Connell... von Hippel PH 1956 κ-Casein and the stabilisation of casein micelles J Am Chem Soc 78: 4576–4 582 White JCD, Davies DT 19 58 The relationship between the chemical composition of milk and the stability... substances in milk and colostrums Brit J Nutr 84 (Suppl 1): S1–S166 Strydom DJ 19 98 The angiogenins Cell Mol Life Sci 54: 81 1? ?82 4 Urashima T et al 2001 Oligosaccharides of milk and colostrums in