Test for Pasteurization Efficiency

Phosphatase Test: Phosphatase test is done to determine whether milk has been properly pasteurized or not immediately after pasteurization of milk. The test is based on the principle that alkaline phosphatase, a natural enzyme present in raw milk, is simultaneously deactivated by heat treatment as specified for pasteurization.When milk-containing phosphatase is incubated with p-nitro phenyl di-sodium ortho phosphate, it hydrolyses the substrate and, as a result, para-nitro phenol is liberated which gives a yellow colour under alkaline condition of the test. The amount of the yellow colour present is directly proportional to the amount of phosphatase present in milk. The presence of yellow colour indicates inefficient pasteurization or post-pasteurization contamination of the milk. The intensity of the colour is compared with standard and lavibond comparator disc.