Determination of Sterols in Foods: Recovery of Free, Esterified, and Glycosidic Sterols

A reliable method for routine use in the determination of sterols in foods is described. In the sample preparation procedure, acid hydrolysis prior to alkaline saponification was used to liberate glycosidic sterols. Sterols were analyzed by capillary gas chromatography as the trimethylsilyl ether derivatives and quantified using an internal standard (dihydrocholesterol). In method development, the main focus was on optimization of hydrolysis conditions and on extraction of sterols after hydrolysis. Performance of the proposed method was compared to the same method without the acid hydrolysis step. Method validation included recovery tests of added free sterol, esterified sterol, and glycosidic sterol. Major plant sterols, including stanols, and cholesterol could be quantitated at levels 0.5–800 mg/100 g when the method was applied to food samples.