Production and utilization of milk

The constituents of milk can be grouped into four general classes according to their source  

The principal constituents (lactose, lipids and most proteins) of milk are synthesized in the mammary gland from constituents absorbed from blood. However, considerable modification of constituents occurs in the mammary gland the constituents are absorbed from blood through the basal membrane, modified (if necessary) and synthesized into the finished molecule (lactose, triglycerides, proteins) within the mammocyte (mainly in the endoplasmic reticulum) and excreted from the mammocyte through the apical membrane into the lumen of the alveolus. 

We believe that it is best and most convenient to describe the synthesis of the principal constituents in the appropriate chapter. 

Some milk and dairy products are consumed in probably all regions of the world but they are major dietary items in Europe, North and South America, Australia, New Zealand and some Middle Eastern countries. Total milk production in 1996 was estimated to be 527 x 10 tonnes, of which 130, 

26 X 10 tonnes were produced in western Europe, eastern Europe, North America and the Pacific region, respectively (IDF, 1996). The European Union and some other countries operate milk production quotas which are restricting growth in those areas. Data on the consumption of milk and dairy products in countries that are members of the International Dairy Federation (IDF) are summarized in Tables 1.2-1.6. Milk and dairy products are quite important in several countries that are not included in Tables 1.2-1.6 since they are not members of the IDF. 

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Milk protein products. As indicated in Table 1, the food industry is placing major emphasis on the production and utilization of milk protein products in a wide variety of formulated food products (20,21,22). Although nonfat dry milk (NFDM) and whey powder are major milk protein ingredients in formulated foods, casein and whey protein concentrates, which contain their proteins in a more highly concentrated and functional form, are essential for certain food product applications, such as those products that require the proteins as an emulsifier agent. Additional details on the processing methods and conditions used to produce the various milk protein products are available (23). 

In 1990, U.S. milk production was 67.4 X 10 t from neatly 10.1 X 10 cows. In the United States there has been an increase in quantity of production with a decrease in number of dairy cows. The wodd production in 1987 was 463.4 X 10 t from 50 X 10 cows. Table 12 gives the 1990 production and utilization of fluid and milk products (15). Table 13 gives the total U.S. pet capita consumption. 

Mulvihill, D.M. (1992) Production, functional properties and utilization of milk protein products, in Advanced Dairy Chemistry, Vol, 1 Proteins, (ed. P.F. Fox), Elsevier Applied Science, London, pp. 369-404. 

Milk and Milk Replacers. White pan bread was long made with about 3—4% nonfat dry milk (NEDM) in the United States, for reasons of enhanced nutrition, increased dough absorption, improved cmst color, fermentation buffering, and better flavor. Eor some years, however, sharply increased milk prices have led to a decline in its use in breadmaking. Many bakers have turned to the use of milk replacers to control the costs of their products, and these ingredients are now commonly utilized. Milk replacers were designed to dupHcate some of the functions and nutrition of milk. These blends may contain soy flour or cereals, with whey, buttermilk soHds, sodium or calcium caseinate, or NEDM. Milk replacers or NEDM used in bread dough amount to about 1—2%, based on flour. 

Hobman, P. G. 1984. Review of processes and products for utilization of lactose in depro-teinated milk serum. J. Dairy Sci. 67, 2630-2653. 

Mortensen, B. K. (1985). Recent developments in the utilization of milk proteins in dairy products. Proc. Int. Congr. Milk Proteins (Galesloot, T. E., and Tinbergen, B.-J., eds.), Luxemburg, pp. 109-119. 

Aspects of the Production, Storage, and Utility of Dry Milk Products. 46... 

Lipids and phospholipids The study of phospholipid monolayers adsorbed on a mercury electrode and the interaction between phospholipids and proteins has been an active research topic for a number of years. The reason for this is obvious when one considers the currently accepted fluid mosaic model of the bilayer lipid membrane (BLM). In addition to its role as a structural element in cells, etc., the BLM is also important in some foods. Since there is enough phospholipid in milk to form a film on a greatly expanded oil-water interface, this lipid undoubtedly plays an important role in stabilizing dairy and other food products that utilize homogenized milk [123]. 

Vegetable proteins other than that from soy have potential appHcability in food products. Functional characteristics of vegetable protein products are important factors in determining their uses in food products. Concentrates or isolates of proteins from cotton (qv) seed (116), peanuts (117), rape seed (canola) (118,119), sunflower (120), safflower (121), oats (122), lupin (123), okra (124), and com germ (125,126) have been evaluated for functional characteristics, and for utility in protein components of baked products (127), meat products (128), and milk-type beverages (129) (see Dairy substitutes). 

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