Food Chemistry 33 (1989) 301-310 Oxidation of Stigmasteroi in Heated Triacylglycerols George Blekas & Dimitrios Boskou Faculty of Chemistry, Laboratory of Organic Chemical Technologyand Food Chemistry, University of Thessaloniki, Thessaloniki 54006, Greece (Received 2 September 1988; revised version received and accepted 9 November 1988) A BS TRA C T A triacylglycerolmixture containing 5% stigmasterolby weight anddevoidof other unsaponifiables was heated at 180 +_ 5°C for several hours. Oxidation products from stigmasterol were separated and isolated by column chromatography and preparative thin-layer chromatograph)'. Characteriza- tion of individual compounds was based on chromatographic mobilities, specific colour reactions, UV and IR spectroscopy and fragmentation patterns from the mass spectra of the purified oxidation products. A hydrocarbon ( stigmasta-3,5,22-triene ), a triunsaturated ketosteroid (stigmasta-3,5,22-trien-7-one), a diunsaturated ketosteroid (stigmasta- 4,22-dien-3-one ) and a pregnane derivative ( A S-pregnen-3fl-oL2-one ) were identified. There is also evidence for the presence of more polar compounds such as hydroxy and epoxy derivatives. INTRODUCTION Stigmasterol is a widely distributed phytosterol and occurs in soybean oil and other vegetable oils and fats (Itoh et al., 1973; Seher & Vogel, 1976). Such oils are often subjected to conditions which are suitable for the oxidation of acylglycerols and unsaponifiables. It is particularly important ~o identify the oxidation products formed by heating of sterols because some of these products have been found to be angiotoxic and/or carcinogenic in experimental animals (Smith & Kulig, 1975; Finocchiaro & Richardson, 1983). 301 Food Chemistry 0308-8146/89/$03"50 © 1989 Elsevier Science Publishers Ltd, England. Printed in Great Britain