Journal of Dairy Research

Original Articles

73. Phosphorus Compounds of Milk. VI. The Effect of Heat on Milk Phosphatase. A Simple Method for Distinguishing Raw from Pasteurised Milk, Raw from Pasteurised Cream, and Butter made from Raw Cream from that made from Pasteurised Cream1

H. D. Kaya1 and W. R. Graham Jra1

a1 From the National Institute for Research in Dairying, University of Reading, and the Department of Biochemistry, University of Toronto.

A method is described for the quantitative determination of phosphatase in raw milk. Using this method, it has been found that phosphatase is sufficiently thermolabile to be destroyed completely by pasteurisation if this process is properly carried out. The absence of phosphatase from a sample of milk or cream indicates with a fair degree of certainty that the milk or cream has been heated sufficiently to destroy such pathogenic organisms as were originally present, though it is of course no guarantee that the product is free from these organisms at the time of testing.

A simple, qualitative test-tube method is described which may be used for differentiating between raw and heated milk, or between raw and heated cream, and which with slight modifications may also be used for distinguishing between butters made from raw or from heated cream.

(Received August 24 1933)


1 A short summary of conclusions reached in the earlier stages of this work was communicated to the Royal Society of Canada (Section V) on May 19, 1933, at the Kingston meeting.