Decomposition of Tocopherol Homologs and Their Effects on the Decomposition of Unsaturated Fatty Acids in 10 Commercial Oils During Deep Frying

The decomposition of tocopherol homologs and their influences upon the decomposition of unsaturated fatty acids were explored by studying the reduction in tocopherol homologs and fatty acid contents in 10 commercial edible oils during deep frying at 180 degrees C. The results showed that the decomposition of total tocopherols was faster than for the total unsaturated fatty acid (TUFA). With the decomposition of TUFA, the decomposition rates of tocopherol homologs were in the order gamma-tocopherol > alpha-tocopherol > delta-tocopherol in 10 oils, regardless of the initial content and composition of tocopherol and fatty acids. It was also found that higher oil unsaturation led to slower tocopherol decomposition during frying, with more tocopherol remaining after the procedure. The result of multiple regression analysis (Delta TUFA(t) = 0.049 Delta alpha(t) + 0.044 Delta gamma(t) + 0.052 Delta delta(t) + 0.733) revealed that the effects of tocopherol homologs on the decomposition of unsaturated fatty acid in 10 oils during frying were in the same order, that is, gamma-tocopherol > alpha-tocopherol > delta-tocopherol.