RAPID-DETERMINATION OF CHOLESTEROL IN MILK AND MILK-PRODUCTS BY DIRECT SAPONIFICATION AND CAPILLARY GAS-CHROMATOGRAPHY

A simple method is described for the determination of cholesterol in m ilk and milk products. Samples (0.2 g) are saponified in capped tubes with 0.5 M methanolic KOH solution by heating for 15 min at 80 degrees C. Water is added to the mixtures, and the unsaponifiable fractions a re extracted with hexane to be further analyzed by capillary gas chrom atography. Because of the rapid sample preparation and gas chromatogra phic procedures, a single sample can be analyzed in 30 min. Overall re covery was 98.6%, and the linearity was excellent for the fortificatio n range examined. Precision data that were based on the variation with in and between days suggested an overall relative standard deviation v alue of 1.4%. The method has been successfully applied to quantitate c holesterol in a variety of milk products.