Milk and dried milk, buttermilk and buttermilk powder, whey and whey powder -- Detection of phosphatase activity
ISO/TS 6090|IDF/RM 82:2004 specifies a screening method for the detection of the phosphatase activity in cow's milk and dried milk, buttermilk and buttermilk powder, and whey and whey powder.
Two alternative procedures (A and B) are given. Procedure A is the simpler as it does not include a clarification treatment and is especially suited for milk. Procedure B includes a clarification step which allows a more sensitive detection through which better quantitative results can be obtained, if desired.
If either method is used for checking the proper pasteurization of these products or their raw materials, then further tests are necessary to ensure that the phosphatase activity is not due to either heat-stable microbial phosphatase or reactivated phosphatase.