Whey proteins proteose-peptones

About 20% of the total protein of bovine milk belongs to a group of proteins generally referred to as whey or serum proteins or non-casein nitrogen. Acid and rennet wheys also contain casein-derived peptides both contain proteose-peptones, produced by plasmin, mainly from /J-casein, and the latter also contains (glyco)macropeptides produced by rennets from K-casein. These peptides are excluded from the present discussion. 

Figure 9.14 The denaturation of the total ( ) and individual whey proteins in milk, heated at various temperatures for 30 min /l-lactoglobulin ( ), a-lactalbumin (O). proteose peptone ( ), immunoglobulins (A), and serum albumin ( ) (from Webb and Johnson, 1965).

In addition to the caseins and whey proteins, milk contains two other groups of proteins or protein-like material, i.e. the proteose-peptone fraction and the non-protein nitrogen (NPN) fraction. These fractions were recognized as early as 1938 by Rowland but until recently very little was... 

Cow s milk proteins are divided into 2 parts caseins and whey proteins. The major fraction of milk proteins (approximately 80 %) belongs to casein group which consists of si-, as2", and K-casein and their portions are nearly 38, 10, 36 and 12, respectively, with respective molecular masses of 23,164, 25,388, 23,983 and 19,038 Da [2]. Proteose peptones and y-casein are obtained through splitting jS-casein by plasmin, a proteolytic enzyme naturally present in mUk. Caseins can be distinguished from other milk components by precipitating near their isoelectric pH ( 4.6 at 20 °C). Caseins are amphiphihc molecules with hydrophihc and hydrophobic segments [3] and are widely used as emulsifier in the food industry due to their amphiphilic character [3, 4]. 

Whey proteins are consisted of ]S-lactoglobulin, a-lactalbumin, proteose peptone, serum albumin, immunoglobulins and lactoferrin. In contrast with caseins, they are... 

Whey proteins a—lactalhumin P-lactoglobulin Serum albumin Proteose peptones... 

Elgar, D.F. Norris, C.S. Ayers, J.S. Pritchard, M. Otter, D.E. Palmano, K.P. Simultaneous separation and quantification of the major bovine whey proteins including proteose peptone and caseinomacropeptide by reversed-phase high-performance liquid chromatography on polystyrene ivi-nylbenzene. J. Chromatogr. A, 2000, 878, 183-196. 

Fig. 10.17. Denaturation of whey proteins by heating at various temperatures for 30 min. 1 Total whey protein, 2 p-lactoglobulin, 3 a-lactalbumin, 4 proteose peptone, 5 immunoglobulin, 6 serum albumin...

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