Rapid determination of alkaline phosphatase activity in cheese.

A visual screening method specifying phenolphthalein monophosphate as the substrate was applied to cheese by analyzing the extract obtained with 7.5% butanol. In the extraction step, all of the alcohol was added at one time, and the mixture was filtered after mixing. Analysis of 10 samples of various types of cheese resulted in data identical to that obtained by the Scharer rapid method. Quantitative data obtained by dialysis of the butanol filtrate and spectrophotometric measurement of the phenolphthalein compared favorably (r = 0.96) with data obtained by the Scharer spectrophotometric method on 13 samples of cheese.