Indigenous enzymes in milk: Overview and historical aspects—Part 2

Abstract

Between 1924 and about 1970, many indigenous enzymes were identified in milk. These were important as indicators of the adequate pasteurisation of milk (alkaline phosphatase, g-glutamyl transferase) or of mastitis (N-acetylglucosaminidase, acid phosphatase) and some were considered to be important for the stability of milk (superoxidase dismutase, sulphydryl oxidase). Human and equine milk both contain a very high level of lysozyme, which is considered to have a significant protective effect on the neonate. Progress on the isolation and characterisation of these seven enzymes first isolated in the period 1925-1970, as well as ribonuclease, aldolase and glutathione peroxidase, from the milk of the cow and other species and their significance in milk and dairy products is reviewed in this article. r

Composition and properties of bovine colostrum: a review

“…The concentration of alkaline phosphatase is very high in colostrum and decreases to a minimum within 1-2 weeks of parturition, before increasing and reaching a constant level after approximately 25 weeks (Shakeel Ur-Rehman and Farkye 2002;Fox and Kelly 2006b). The concentration of acid phosphatase is low in colostrum initially, increases to a maximum over 5-6 days post-partum, and then decreases and remains low until the end of lactation (Shakeel urRehman and Farkye 2002).…”

Future Challenges of Whey Proteins

“…It is widely distributed in nature, occurring in many body fluids and tissues of living organisms (Fox and Kelly, 2006). The highest concentration of the enzyme was found in tears and egg white protein, which is currently the basic source of its obtaining on an industrial scale.…”

Effect of Somatic Cell Count on Bovine Milk Protein Fractions

“…The increase in plasmin activity is caused by somatic cells from its inactive precursor plasminogen, which is converted into plasmin, in a process initiating in the mammary gland and continuing throughout the storage period [7,8,10,11]. Increased SCC in milk results in elevated activation of plaminogen into plasmin, that in turn leads to high breakdown of some proteins chains, primarily β-casein, because protein fraction partially diffuses into solution at low temperature, which facilitates enzyme attack, producing small fragments, such as γ-caseins and other small peptides that diffuse to the aqueous phase of the milk [12,13]. This protease has specificity for Lys-x and Arg-x bonds [13][14][15].…”

“…Increased SCC in milk results in elevated activation of plaminogen into plasmin, that in turn leads to high breakdown of some proteins chains, primarily β-casein, because protein fraction partially diffuses into solution at low temperature, which facilitates enzyme attack, producing small fragments, such as γ-caseins and other small peptides that diffuse to the aqueous phase of the milk [12,13]. This protease has specificity for Lys-x and Arg-x bonds [13][14][15].…”