title: Oxidation reactions of steryl esters in a saturated lipid matrix.
abstract: In the present study, the formation and further reactions of intact steryl ester hydroperoxides were followed in a tripalmitin matrix maintained at 100°C. The effects of the acyl moiety and its unsaturation degree, and of the sterol structure were investigated. Intact steryl ester hydroperoxides were isolated from the lipid matrix by a developed solid-phase extraction (SPE) method and were determined by HPLC-ELSD. Further reactions of hydroperoxides were followed by determining secondary oxidation products of sterol by GC-FID/MS and oligomers by HPSEC-RI. The oxidation of sterol decreased when its solubility in the lipid medium was increased by introduction of acyl moiety. Increased unsaturation of the acyl or steryl moiety of steryl ester shortened the induction period and increased the oxidation of both steryl and acyl moieties. Thus, by changing the chemical and physical properties of sterols, their oxidation may be greatly affected.
authors: Department of Food and Environmental Sciences, Division of Food Chemistry, University of Helsinki, P.O. Box 27, FI-00014 Helsinki, Finland. mari.lehtonen@helsinki.fi
authors: Mari
authors: M
authors: Lehtonen
authors: Anna-Maija
authors: AM
authors: Lampi
authors: Mari-Anna
authors: MA
authors: Riuttamäki
authors: Vieno
authors: V
authors: Piironen
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004952:Esters / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D008055:Lipids / Q000737:chemistry*; D010084:Oxidation-Reduction; D013261:Sterols / Q000737:chemistry*
chemical_list: D004952:Esters; D008055:Lipids; D013261:Sterols