A multivariate study of α-tocopherol and hydroperoxide interaction during the oxidation of methyl linoleate

Interactions between α-tocopherol (α-TOH) and lipid hydroperoxides (LOOH) during the oxidation of methyl linoleate were studied in a model system using the response surface methodology statistical technique. When no α-TOH is present, LOOH had only slight prooxidative effects on the oxidation of methyl linoleate. High initial levels of α-TOH caused increased consumption and loss of efficiency for this antioxidant. The time for α-TOH consumption and the induction period for the oxidation of methyl linoleate were increased by increasing initial α-TOH concentration but were decreased by increasing initial LOOH as well as by interactions between LOOH and α-TOH. Interactions among LOOH molecules and between LOOH and α-TOH molecules had negative effects on the stability of α-TOH and the rate of oxidation of methyl linoleate as evidenced by the rate of α-TOH consumption, the rate of LOOH formation, the ratio of cis,transltrans,trans LOOH and the rates of formation of hydroxy and ketodiene compounds during the induction period. Thus, the efficiency of α-TOH as an antioxidant is determined by, as yet unknown, interactions involving α-TOH and/or LOOH which are both present during the induction period.