Effect of heat treatment on lactoperoxidase activity in caprine milk

Using isothermal conditions, inactivation of lactoperoxidase (LPO) in caprine milk was studied in a temperature range of 69-73 degrees C. In order to evaluate the effect of temperature on the reaction rate, the Arrhenius and thermal death time models were used for data analysis. Thermal inactivation of LPO can be accurately described by a first-order kinetic model, as indicated by the relationships obtained by plotting the retention values as a function of treatment time on a semi-logarithmic scale and confirmed by the high R-2-values obtained. D- and k-values decreased and increased, respectively with increasing temperature, indicating a more rapid LPO inactivation at higher temperatures. The corresponding Z- and E-a-values calculated from the slope of the semi-logarithmic plots of D and k as a function of temperature were 9.45 C and 225.98 kJ/mol, respectively. (c) 2005 Elsevier B.V. All rights reserved.