Effect of High-Temperature Short-Time Heat Treatments on Some Properties of Milk. I. Inactivation of the Phosphatase Enzyme

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Abstract
The phosphatase activity of raw milk and the distribution of phosphatase in various milk fractions were determined. Most of the phosphatase is believed to be located at the fat-serum interface. Separation temps. up to 120 F did not appreciably change the distribution of the phosphatase in the cream and skim milk fractions. The lower the phosphatase activity in the milk the less the difference in the phosphatase activity in the cream over that in the milk. A standard of 1 ppm. phenol was selected as satisfactory destruction. From the studies of the kinetics of phosphatase inactivation by heat, and time-temp. relationship, a mathematical solution for time temp. cycles is obtained. If the phosphatase test is used as the standard for adequate pasteurization, this mathematical solution can be applied to determine the proper time-temp. conditions.