Analysis Phenols Components And Antioxidant Properties Of Peel,flesh,seed From Different Kiwifruit Cultivars

Nowadays,as one of the most popular fruits,kiwifruit is characterized by a high content of Vc and other useful compounds such as phenols.Shaanxi is the largest production area of kiwifruit in China,whose main cultivars is Jingxiang,Xuxiang,Yate,Qihong,Jinglong,Nongdamixiang,Miliang,and Hayward ect.At present,there are relatively more researches on the functional active components of kiwifruit flesh,but there are few reports on the analysis and antioxidant activity of phenols in the peel and seeds of different kiwifruits.Therefore,this thsis systematically analyzed the phenolic active components and their antioxidant activity in different cultivars and parts of kiwifruit,and the main research contents are as follows:?1?In this study,the total amount of polyphenol was used as the testing index,and the response surface method?RMS?was applied to optimice the extraction process of polyphenols in kiwifruit pulp by using ultrasonic assistance.Four independent variables,including ethanol concentration,liquid-material ratio,ultrasonic power and ultrasonic time,were studied.The optimized conditions were as follows:the concentration of ethanol was60%,ratio of liquid to material was 23:1,ultrasonic power was 450 W.?2?According to by HPLC experimens,there are abundant phenolic compounds in different parts of kiwifruit,and 17 kinds of phenolic compounds were determined quantitatively.Catechin,chlorogenic acid,protocatechuic acid and quercetin are abundant in the peel,flesh,and seeds of kiwifruits.The polyphenol components in different cultivars were significantly different,where the amount of catechin reached the highest of 356.38 mg/kg in the peel of Xuxiang,chlorogenic acid reached to the highest of 215.65 mg/kg in the peel of Nongdamixiang and quercetin of Miliang seed reached to 245.65 mg/kg.?3?The vitamin C,polyphenols and flavonoids in peel,flesh,and seed of different cultivar of kiwifruit were detected.It turned out that the cultivars named Jonglong and Nongdamixiang contained the highest level of Vc.The content of polyphenols in Nongdamixiangs peel was significantly higher than other cultivars.Similar situation occurred to the flavonoids in the of Miliang.By DPPH,ABTS of the free radical scavenging ability,and iron force reducing antioxidant power assay,it was found that the antioxidant capacity was positively correlated with polyphenol components.?4?The kiwifruit peel extract was use to interferes the oxidative stress induced by hydrogen peroxide?H₂O₂?of 200?M in HepG2 liver cells.The extract of kiwifruit alleviates the level of reactive oxygen species?ROS?and the damage of mitochondrial function in HepG2 liver cells induced by hydrogen peroxide,increases the vitality of cells,and it was also found that the expression of the downstream related anti-oxidase II enzyme in Keap1/Nrf2 signaling pathway was up-regulated,which indicated that the extract of kiwifruit peel has a good effect on the oxidative streess of HepG2 liver cells.This paper studied the active component and antioxidant activity in different parts of different cultivars of kiwifruit and provided theoretical basis for the deep processing and utilization of kiwifruit byproducts.