Abstract
The effects of oxidized products (OP) and gallic acid (GA) on the decomposition of tocopherol (Toc) in soybean and hardened rapeseed oils during autoxidation at 60°C were investigated. OP are fatty substances insoluble in petroleum ether, that are separated from fatty acids after saponification of heated oils. Oils (10g) with or without OP. GA and a mixture of these substances were placed in glass beakers and allowed to oxidize in an incubator at 60°C. Then, the Toc and peroxide values of the oils were determined by both HPLC and the JOCS official method 2. 4. 12-71, respectively. Increases in peroxide values and decomposition of Toc in oils were apparently promoted by the added OP, and decomposition of Toc increased with the increased concentration of OP. Also, decomposition of ethanolic Toc by added OP was observed during storage at 60°C. Therefore, decomposition of Toc by OP may be attributable to the oxidative reaction of OP. On the other hand, GA showed remarkable suppression of Toc decomposition by OP.
