Effects of sterol structure, temperature, and lipid medium on phytosterol oxidation.
Factors contributing to the oxidative stability of phytosterols were studied. Unsaturated stigmasterol and saturated sitostanol were used as model compounds and were heated at different temperatures in different lipid matrices for various periods of time. Accumulations of the major secondary oxidation products were used as a marker of the stability of heated compounds, and the products were analyzed by gas chromatography-mass spectrometry. The results showed that both temperature and heating time, as well as sterol structure and lipid matrix composition, affected phytosterol oxidation. In particular, the interactions between different lipid matrices and temperatures had drastic effects on the total contents of the phytosterol oxides formed and also on the reaction pathways of oxidation. During heating at high temperatures for prolonged periods, >20% of stigmasterol was oxidized. At moderate temperatures the oxidation of stigmasterol was rather slow. Sitostanol oxide contents were low under all heating conditions studied.
Department of Applied Chemistry and Microbiology, University of Helsinki, Latokartanonkaari 11, P.O. Box 27, FIN-00014 University of Helsinki, Finland. Laura.Soupas@helsinki.fi
Laura
L
Soupas
Laura
L
Juntunen
Anna-Maija
AM
Lampi
Vieno
V
Piironen
D004355:Drug Stability; D005511:Food Handling / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D006358:Hot Temperature; D008055:Lipids / Q000737:chemistry*; D010084:Oxidation-Reduction; D010840:Phytosterols / Q000737:chemistry*; D012855:Sitosterols / Q000737:chemistry; D013265:Stigmasterol / Q000737:chemistry; D013997:Time Factors
D008055:Lipids; D010840:Phytosterols; D012855:Sitosterols; D013265:Stigmasterol; C021255:stigmastanol