Studies on dimerisation of tocopherols under the influence of methyl linoleate peroxides

✍ Scribed by Gogolewski, Marek ;Nogala-Kalucka, Malgorzata ;Galuba, Grzegorz

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 417 KB
• Volume: 47
• Category: Article
• ISSN: 0027-769X
• DOI: 10.1002/food.200390030

✦ Synopsis

Abstract

The stability of plant oils is related to the level of polyunsaturated fatty acids and the presence of native antioxidants – especially tocopherols. During storage, lipids or the fat products undergo oxidation and tocopherol dimers and trimers are formed. These compounds possess reducing and antioxidant properties and participate in oxidation clearly inhibiting this process. In the present study, the correlation between levels of peroxides formed during autoxidation of methyl linoleate and simultaneous decomposition of tocopherols was examined. The peroxide value was investigated. Quantities of decomposed tocopherols and formation of their dimers were determined by high‐performance liquid chromatography (HPLC). Mass spectrum analysis confirmed that the analysed compounds were dimers. Dimerisation of γ‐T begins at the smaller quantity of the methyl linoleate peroxides than dimerisation of δ‐T. At the beginning of methyl linoleate autoxidation dimerization of γ‐T in relation to its loss was smaller. The quantity of γ‐T dimers with ether bonds in total dimers pointed to faster binding of phenoxy radicals than transformation into the phenyl ones. δ‐T dimers with phenyl bonds constitute about 65% of the total. The quantity of peroxides in methyl linoleate, necessary for quantitative and qualitative changes of homologous tocopherols, decreased from δ‐T to α‐T.