Antioxidative effects of sesamol and tocopherols at various concentrations in oils during microwave heating

The effectiveness of sesamol and tocopherols or their mixtures at different concentrations (50 to 800 ppm) on the oxidative stability of tocopherol-stripped oils was studied under microwave heating conditions. Microwave heating accelerated the oxidation of the purified substrate oils. The oxidative deterioration of the oils was significantly (P < 0.05) retarded during microwave heating by the addition of sesamol or tocopherols, and also mixtures of these antioxidants. A combination of sesamol and gamma-tocopherol was more efficient than that of sesamol and the other tocopherol homologues in inhibiting hydroperoxide formation in the oils. Useful levels of these antioxidants were 400 ppm for tocopherols and 50-400 ppm for sesamol. In general, the residual amount of sesamol in the oils during microwave heating was significantly greater (P < 0.05) than that of tocopherols. Very effective combinations of tocopherols and sesamol as antioxidants for the purified oils were 200 or 400 ppm of gamma-tocopherol and 50, 200 or 400 ppm of sesamol, respectively. (C) 1999 Society of Chemical Industry.