Detection of olive oils authenticity by determination of their sterol content using LC/GC

Abstract

AB: Contents of selected sterols, limits for which are declared in EEC Commission Regulation No. 2568/91 (1991), were used to determine the authenticity of olive oils. A modified method using preparative LC on a silica gel packed column and gradient elution with hexane-diethyl ether was used to separate undesirable interfering compounds in the unsaponifiable fraction before determination of sterols by GC. Model experiments based on determination of Delta-7-stigmastenol, campesterol and brassicasterol were used to verify that this method is applicable for identification of adulteration of olive oils by sunflower, soybean or rapeseed oil, respectively. The method enabled detection of 5-10% of oils added to the olive oil. 5 samples of olive oil from the SIAL exhibition (Paris) and 10 samples of virgin olive oil obtained in Prague markets were analysed by this method. Adulteration of the samples was not proved