Precision and sensitivity of a test for vegetable fat adulteration of milk fat.

A test for routine screening of Mozzarella cheese and butter for vegetable fat adulteration is described. Fat is extracted and saponified. The potassium salts of the fatty acids are measured through direct gas chromatographic analysis. A ratio, calculated from the concentrations of butyric and oleic acids, is used to evaluate the purity of a sample. The test offers good precision and can detect less than 10% partially hydrogenated vegetable fat.