Invited review: Plasmin protease in milk: Current knowledge and relevance to dairy industry

• Published in: Journal of dairy science 2010-11, Vol.93 (11), p.4999-5009
• Main Authors: Ismail, B., Nielsen, S.S.
• Format: Article
• Language: English
• Subjects: Animal productions; Animals; bacterial proteases; Biological and medical sciences; casein; Cattle; cheeses; dairy product quality; Dairy Products; enzyme activation; enzyme activity; enzyme inhibition; Fibrinolysin - analysis; flavor; Food Handling; Food industries; food processing; food processing quality; food quality; food storage; Fundamental and applied biological sciences. Psychology; gelation; literature reviews; milk; Milk - enzymology; Milk and cheese industries. Ice creams; milk composition; Milk Proteins - analysis; milk quality; pasteurized milk; plasmin; production costs; protease-protease inhibitor system; proteinase inhibitors; proteolysis; sensory properties; storage conditions; Terrestrial animal productions; texture; traits; UHT milk; Vertebrates; whey
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2010-3122

Plasmin is by far the predominant and most completely studied endogenous protease in bovine milk. Plasmin-induced proteolysis can have either beneficial or detrimental effects on the texture and flavor of dairy products, depending on the extent of hydrolysis and type of dairy product. In cheese, the breakdown of protein can help develop desirable flavors and texture during ripening, whereas in pasteurized milk and ultra-high-temperature milk, proteolysis causes undesirable gelation. Plasmin is part of a complex protease–protease inhibitor system in milk that consists of active and inactive forms of the enzyme, activators, and inhibitors. Considerable research has been done to isolate and characterize components of the plasmin system, determine how they interact, develop and compare quantitation methods, and determine how they are affected by cow characteristics, processing conditions, other milk components, storage conditions, and bacterial proteases. Considerable research has focused on enhancing or minimizing the activity of plasmin system components. The intent has been to control protease activity in casein and whey fractions, depending on the final food or ingredient application. Controlling the activity of plasmin has a great potential to improve dairy product quality and reduce their processing costs.