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THERMAL INACTIVATION KINETICS OF ALKALINE PHOSPHATASE IN BUFFER AND MILK
Author(s) -
FADILOĞLU S.,
ERKMEN O.,
ŞEKEROĞLU G.
Publication year - 2006
Publication title -
journal of food processing and preservation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.511
H-Index - 48
eISSN - 1745-4549
pISSN - 0145-8892
DOI - 10.1111/j.1745-4549.2006.00063.x
Subject(s) - pasteurization , chemistry , raw milk , kinetics , alkaline phosphatase , d value , arrhenius equation , reaction rate constant , activation energy , kinetic energy , enzyme , chromatography , food science , analytical chemistry (journal) , biochemistry , physics , quantum mechanics
A detailed kinetic study on the thermal inactivation of alkaline phosphatase (ALP) added into buffer and pasteurized milk and for ALP naturally present in raw cow's milk has been performed. Kinetic parameters (rate constant, k ; decimal reduction time, D ; activation energy, E a ; and z value) were evaluated based on the first‐order rate model at 50–80C. The temperature sensitivity of the kinetic parameters was evaluated considering the Arrhenius‐type E a model. All kinetic behaviors were well described by the first‐order model ( r 2 > 0.91). The D values increased with increasing temperature. Higher temperatures resulted in higher rates of enzyme inactivation as indicated by lower D values and higher k values. There are significant differences ( P < 0.01) among the D values for ALP in buffer and milk at treated temperatures. The rate of enzyme inactivation was much more rapid in buffer than in pasteurized milk. The evaluated E a values for ALP added into the buffer and pasteurized milk, and for ALP naturally present in raw milk were 97.2, 149.9 and 207.8 kJ/mol, respectively. The inactivation kinetics of ALP during heat treatment was found to be dependent on the composition of the medium, and the time and temperature of the heat treatment .