Effects of some herbal extracts on oxidative stability of corn oil under accelerated oxidation conditions in comparison with some commonly used antioxidants

A total of 10 corn oil samples, 6 with herbal extracts, 2 with butyl hydroxy toluene (BHT) and ascorbyl palmitate (AP), a refined corn oil and the control, the stripped corn oil, were evaluated for oxidative stability under accelerated oxidation at 60 °C for 6 wk. Oxidation was followed by determining peroxide value, thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and trienes (CT). Antioxidant activity of each herbal extract was evaluated. According to the obtained results, sumac extract, α-tocopherol and AP had the highest antioxidant activity, whereas flaxseed and sage showed the lowest. Peroxide, TBARS, CD and CT values increased during storage in all samples. Samples with BHT, sumac and mint showed the highest inhibition of peroxide formation. Sumac and thyme extracts significantly inhibited TBARS formation compared to BHT and AP added samples. It is concluded that the antioxidant activities of sumac, thyme and mint were high and retarded the oxidation and can be utilized in the food industry for commercial purposes in retardation of oil oxidation.