Study On Polyphenols And Related Enzyme Activities During The Development Of Jujube Fruit

Jujubes are traditional medicinal and edible homologous plants.Jujube fruit is rich in various bioactive substances,which have physiological effects such as tonifying qi and blood,preventing and fighting cancer,protecting the liver and regulating immunity.Therefore,jujube fruit has become an important raw material for human health food and the development of functional foods.In order to screen high-quality jujube germplasm resources and develop their functional components,this study was based on genetic variation analysis of flavonoids and total phenols content in 142 jujube germplasm resources.Four jujube varieties with different content were selected for determination of polyphenol component content,antioxidant activity,and metabolic pathway related enzyme activity.The research results showed that:(1)The contents of flavonoids and total phenols in the fruits of 142 jujube germplasm resources ranged from 1.24 mg/g to 6.61 mg/g and 5.09 mg/g to 19.77 mg/g,with the coefficient of variation of32.48% and 19.68%.The contents of flavonoids and total phenols in the fruits were normal distribution;The 38 resources screened by the membership function analysis results are highly similar to the 35 germplasms of the top three high-quality groups in the cluster analysis results.(2)(2)During the fruit development process of the four jujube varieties,the content of flavonoids,total phenols,and antioxidant activity showed a continuous downward trend from the swelling stage to the full red stage.During the swelling period,’Yongcheng Changhong’ has the highest flavonoid content at115.31 mg/g,while ’Changjixin’ has the lowest flavonoid content at 62.79 mg/g;During the same period,’Jin’ai 4’ had the highest total phenolic content at 20.81 mg/g,while ’Yongcheng Changhong’ had the lowest total phenolic content at 17.72 mg/g.The antioxidant capacity of all four jujube varieties was the strongest during the expansion period.During the expansion period,’Jin’ai 4’ had the strongest DPPH scavenging ability and iron reducing ability,which were 1.75 and 1.86 times that of ’Changjixin’.At the same time,’Yongcheng Changhong’ had the strongest ABTS+scavenging ability,which was 1.81 times that of’Changjixin’ during the expansion period.(3)A total of 18 phenolic components,including 9 phenolic acids and 9 flavonoids,were detected in the fruits of 4 jujube varieties.Among them,(+)-catechin,rutin,quercetin,anthocyanin,epicatechin,protocatechol,and gallic acid were the main components.During three different developmental stages,the content of other substances except epicatechin and anthocyanin showed a decreasing trend,and there were significant differences in the content of phenolic components among different jujube varieties.(4)The changes in enzyme activities related to the metabolism pathway of polyphenols in the four jujube germplasm fruits were basically the same.PAL,CHI,F3 H,FLS,and DFR enzyme activities showed a downward trend from the swelling stage to the white ripening stage and then to the full red stage,while4 CL,CHS,and ANS enzyme activities showed an upward trend.There were significant differences in enzyme activities among the four jujube varieties at different development stages.There is a significant or extremely significant correlation between the content of flavonoids,total phenols,antioxidant activity,and related enzyme activities in jujube fruits at different developmental stages.