Indigenous enzymes of bovine milk

As many as 60 indigenous enzymes have been reported in normal bovine milk. With the exception of a-lactalbumin, which is an enzyme modifier in lactose synthesis (Chapter 2) most, if not all, of the indigenous enzymes in milk have no obvious physiological role. They arise from three principal sources  

most enzymes enter milk due to peculiarities of the mechanism by which milk constituents, especially the fat globules, are excreted from the secretory cells. Milk does not contain substrates for many of the enzymes present, while others are inactive in milk owing to unsuitable environmental conditions, e.g. pH. 

Many indigenous milk enzymes are technologically significant from five viewpoints  

Deterioration (lipase (commercially, probably the most significant enzyme in milk), proteinase, acid phosphatase and xanthine oxidase) or preservation (sulphydryl oxidase, superoxide dismutase) of milk quality. 

As indices of the thermal history of milk alkaline phosphatase, y-glutamyl transpeptidase, lactoperoxidase. 

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Fox, P.F., Morrissey, P.A. 1981. Indigenous enzymes of bovine milk. In Enzymes and Food Processing (G.G. Birch, N. Blakebrough, K.J. Parker, eds.), pp. 213-238, Applied Science Publishers, London. 

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