Antioxidant Properties of Olive Leaf Extract and its Application in Sunflower Oil

In this study the antioxidant properties and total phenolics content of methanol (80%), acetone and water extracts of olive leaves produced by maceration method were examined. Two varieties of olive including Koroneiki and Roghani were studied. Various experimental models including reducing power, total antioxidant capacity and DPPH radical scavenging activity were used for evaluation of antioxidant activity of extracts and compared with synthetic antioxidants (BHA and BHT). At the next stage, effect of methanol extract of Koroneiki on oxidative stability of sunflower were assessed using peroxide value and thiobarbitoric acid index. Results revealed that the highest phenolic content (196.6±0.33 mg TAE/g extract) and the lowest IC50 in DPPH (106.065±0.55 µg/ml), reducing power (258.137±0.16 µg/ml) and total antioxidant capacity (205.9±0.18 µg/ml) indices were related to the methanol extract of Cronaiky. Also, methanolic extract of Cronaiky at 1000 ppm could control peroxide value and thiobarbitoric acid index and could be used instead of BHA and BHT at 100 and 200 ppm levels.