3-4 |
Controlling the location and activity of plasmin system components in dairy products |
S. S. Nielsen and K. D. HAYES. Dept. of Food Science, Purdue Univ., 745 Agricultural Mall Dr., West Lafayette, IN 47907-2009 Plasmin, the major native milk serine proteinase, is an important contributor to proteolytic breakdown in milk and dairy products. Plasmin activity has beneficial proteolytic effects during the ripening of certain cheeses. The whey fraction from cheesemaking is used commonly to make whey protein concentrates and isolates, which then are used as functional ingredients in various food systems. Plasmin activity in whey protein products may cause breakdown of food proteins to have beneficial or detrimental effects on food quality. Plasmin has been implicated as a contributor to age gelation in UHT milk (ultrahigh temperature milk). Factors that affect the location and activity of plasmin system components are economically relevant to the dairy industry. Several factors have been identified that affect the location and activity of plasmin system components in milk, cheese, whey, and milk model systems. Factors investigated include: 1) heifer stage of lactation and lactation number, 2) proteases produced by psychrotrophic bacteria, 3) various cheesemaking conditions, and 4) thermal processing conditions. Each of these factors will be discussed with regard to their potential for controlling plasmin system components in milk, cheese, whey, and model systems.
Session 3, Control of endogenous enzymes in foods: A practical approach
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