Alkaline phosphatase (ALP) is an enzyme naturally present in all raw milks and is considered to be an indicator of proper milk pasteurization. Complete pasteurization will inactivate the enzyme to below levels that are detectable by conventional methods. Because the heat stability of ALP is greater than that of pathogens that may be present in milk, the enzyme serves as an indicator of product safety. However, the failure to detect ALP activity does not guarantee that the product is pathogen-free. Packaged milk can be categorized according to fat and solids-not-fat (SNF) content as follows: a) Full-cream milk: Fat 6.0 per cent and SNF 9
per cent (minimum) b) Toned milk: Fat 3.0 per cent and SNF 8.5
per cent (minimum) c) Double-toned milk: Fat 1.5 per cent and
SNF 9 per cent (minimum) The terms ‘pasteurization’, ‘pasteurized’ and similar terms shall be taken to refer to the process of heating every particle of milk of different classes to at least 63 degrees Celsius and holding it at such temperature continuously for at least 30 minutes, or heating it to at least 71.5 degrees C and holding at such temperature continuously for at least 15 seconds, or an approved temperature–time combination that will serve to give a negative phosphatase test.