LINEAR-TRANSFORM AND NONLINEAR MODELING OF BOVINE-MILK CATALASE INACTIVATION IN A HIGH-TEMPERATURE SHORT-TIME PASTEURIZER

Milk for cheese manufacture is commonly heated at temperatures in the range 63-65 degrees C for about 15 s to reduce bacterial numbers. Thes e heat treatments have been referred to as thermization. There is no g ood method for determining whether a milk has undergone a heat treatme nt equivalent to thermization, although it has been suggested that ina ctivation of milk catalase is indicative of heat treatments in this ra nge. A model has been derived that describes the inactivation of bovin e milk catalase during heating in a high-temperature short-time pasteu rizer. The activity of the enzyme was related to the pasteurization ef fect, a measure of the integrated lethal effect of all sections of the heat exchanger. The data were best described by a biphasic logistic m odel which suggested that the enzyme was slightly more heat stable tha n alkaline phosphatase. Copyright (C) 1996 Canadian Institute of Food Science and Technology