Inactivation kinetics of gamma-glutamyltransferase during the heating of milk.
The inactivation of gamma-glutamyltransferase (GGT, E.C.2.3.2.2) during the heating of milk to between 65.0 degrees C and 76.0 degrees C for periods of 5 s to 1000 s follows a first-order reaction (energy of activation 457 kJ/mol) and can be used to monitor the process of milk pasteurisation. GGT activity in raw milks from individual cows showed only little variation (5.92 +/- 0.59 units). Residual GGT activity in 17 commercial milks ranged between 1% and 20%, indicating a heat treatment at the upper limit of the permitted pasteurisation conditions.
Lehrstuhl für Milchwissenschaft, Technische Universität München, Freising-Weihenstephan, Germany.
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Zehetner
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Bareuther
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Henle
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Klostermeyer
D000818:Animals; D002417:Cattle; D003296:Cooking; D005260:Female; D006358:Hot Temperature; D007700:Kinetics; D008892:Milk / Q000201:enzymology*; D012044:Regression Analysis; D013816:Thermodynamics; D005723:gamma-Glutamyltransferase / Q000037:antagonists & inhibitors*
D005723:gamma-Glutamyltransferase