Study on the microwave- assisted extraction and antioxidant capacity of polyphenols from olive fruits

Response surface analysis methodology ( RSM) was applied to optimize the microwave- assisted extraction conditions of polyphenols from fresh olive fruits, furthermore, the study investigated the antioxidant activity of polyphenols extracts.Based on single factor experiments, a quadratic regression model was established according to the Box- Behnken experimental design.The optimum microwave- assisted conditions were materialliquid ratio 1∶23 ( g / m L) , microwave time 48 s, microwave power 490 W.Validation experiments were carried out at the optimum microwave- assisted conditions, the average yield of polyphenols was 6.9659 mg / g, the relative error between experimental values and the predicted value was 1.12%. It showed that the optimization process was feasible.The maximum inhibition percentage of DPPH and hydroxyl radical of polyphenol extracts were 87.85% and68.12%, respectively. The IC50 value were 0.055 mg / m L and 0.188 mg / m L, respectively. In addition, the maximum chelating rate of Cu2 +was 54.18%, the Cu2 +chelating concentration in half of polyphenols extracts was0.277 mg / m L.