Abstract:Xuxiang kiwifruit was used to determine the content of its total acid,total sugar and vitamin C.Polyphenols from Xuxiang kiwifruit were extracted with ultrasonic extraction.Its total reducing capacity and scavenging activities against four free radicals including hydroxyl radical,superoxide radical,DPPH radical and ABTS radical were identified to evaluate the antioxidant activity of kiwifruit polyphenols using vitamin C as a control.The results showed that the content of total acid,total sugar,and vitamin C in Xuxiang kiwifruit was 1.13%±0.16%,10.03%±0.78% and （78.71±7.60） mg per 100 g,respectively.The content of polyphenols in kiwifruit extract was 0.123 mg/mL.The total reducing capacity of kiwifruit polyphenols was stronger than that of vitamin C.The IC50 value of the scavenging rate for four free radicals of kiwifruit polyphenols was lower than that of vitamin C.It is indicated that kiwifruit polyphenols had high antioxidant activity.The kiwifruit polyphenols analyzed with HPLC contains 6 kinds of polyphenols:gallic acid,fenugreek acid,catechin,chlorogenic acid,caffeic acid and ferulic acid.Caffeic acid was the highest among them.It will provide a theoretical basis for further studying kiwifruit polyphenols.