Ultrasonic-assisted Ethanol Extraction of Flavonoids from Kiwifruit Root and Their Antioxidant Activity

Flavonoids were extracted from Miliang Kiwifruit root under ultrasonic assistance,using ethanol as extraction solvent.The technical conditions were investigated based on single factor and orthogonal tests.The hydroxyl radical-scavenging capacity and the antioxidative activity against oils and fats of the flavonoids extracts were assessed and compared with those of citric acid and Vc.The results show that the optimal extracting conditions were obtained as follows:volume fraction of ethanol 60%,1∶ 30(g∶ mL) material-to-liquid ratio,40 min of ultrasonic extracting time and 60 ℃ water-bath of ultrasonic temperature.Under the optimal conditions,the extraction rate of total flavonoids was 1.5%.The scavenging capability on ·OH free radical increased with extracts concentration increasing.Furthermore,the antioxidant activity of flavonoids extracts against oils and fats was excellent.