A rapid and simple phosphatase test for milk

A simple and rapid phosphatase test is described which is based on the use of p –nitrophenylphosphate as the substrate. Execution of the test requires few and easy operations: incubation of the milk at 37° C. with a buffered solution of the substrate, followed directly by a visual comparison of the intensity of yellow colour of liberated p –nitrophenol with that of boiled-milk standards containing known amounts of p –nitrophenol. The test permits the detection of minor processing faults with an incubation time of only 30 min. In this form it should prove of value in creamery control. A more searching, but equally simple test is obtained by increasing the period of incubation to 2 hr.