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The peroxidizing effect of α‐tocopherol on autoxidation of methyl linoleate in bulk phase
Author(s) -
Terao J.,
Matsushita S.
Publication year - 1986
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02536407
Subject(s) - autoxidation , chemistry , tocopherol , induction period , organic chemistry , methyl oleate , antioxidant , photochemistry , chromatography , vitamin e , stereochemistry , catalysis
Abstract In order to understand the effect of α‐tocopherol on the autoxidation mechanism of edible oil under storage conditions, methyl linoleate was allowed to autoxidize at 50 C in bulk phase without any radical initiator. The reaction was monitored by determining the production of four isomeric hydroperoxides ( 13‐cis,trans; 13‐trans,trans; 9‐cis,trans; 9‐trans,trans ) by high performance liquid chromatographic analysis after reduction. In the absence of α‐tocopherol, the rate of autoxidation depended on the sample size, and the duration of the induction period was affected by the initial level of hydroperoxides. However, the distribution of c‐t and t‐t hydroperoxide isomers remained constant during the propagation period regardless of the sample size. The addition of α‐tocopherol at 0.1 and 1.0% caused a linear increase in the amount of hydroperoxides and elevated the distribution of the c‐t isomers. The rate of hydroperoxidation appeared to be governed by the initial concentration of α‐tocopherol rather than the sample size or the initial hydroperoxide level. This peroxidizing effect of α‐tocopherol was suppressed by the presence of ascorbyl palmitate. A mechanism in which chromanoxy radical participates is proposed for the effect of α‐tocopherol on lipid autoxidation in bulk phase. It is therefore suggested that α‐tocopherol at high concentrations influences the mechanism of autoxidation of edible oil.