Evaluation of antioxidant effect of Kiwifruit ( Actinidia deliciosa L.) peel extract in comparison with TBHQ synthetic antioxidant on oxidative stability of soybean oil

In this study, the extracts of Kiwifruit peel were prepared by ultrasound assi sted method (probe and bath) and the total phenolic and flavonoid compounds were measured. Then the antioxidant activity of the sample, which had the highest amount of phenolic compounds, was studied on soybean oil. The most phenolic and flavonoids compoun ds were respectively 320±0.32 (mg gallic acid/g of extract) and 4.593±0.5 (mg quercetin/g of extract) of the extract that was extracted by ultrasound probes assiste dmethod. This extract at three concentrations 1500, 2000 and 2500 mg/L and synthetic antiox idant TBHQ at 100 mg/L separately were added to soybean oil without antioxidants. The effect of treatments on delaying the oxidation of soybean oil at 63 ° C during 16 days of storage at (0, 2, 4, 6, 8, 10, 12, 14 and 16 intervals), by measuring the peroxi de value (PV), thiobarbituric acid (TBA) and conjugated dien value (CDV) were investigated. In all samples, the blank sample, which had no antioxidant, showed the high est number of peroxide, thiobarbituric acid and conjugated dien. The concentration of 250 0 mg/L of Kiwifruit peel extract was significantly different (P<0.05) than TBHQ and other concentrations in oxidative stabilization of soybean oil during oven test period. Therefore, Kiwifruit peel extract can be consi dered as a natural antioxidant and an alternative for synthetic antioxidant in the food industry.