Biochemical Basis Of Anthocyanin Formation In Purple Tea And Its Effect On The Quality Of Tea Products

AS an important water-soluble pigment in nature,Anthocyanins are one of the basic material that form the color of many plant leaves,flowers and fruits^[1].Tea are used as evergreen leaves.The color of buds has a close relationship with the contents of fresh leaves,the suitability of fresh leaves and the quality of tea.The research have shown that the more anthocyanin in fresh leaves,the darker the color of the leaves.In recent years,it has focused on genes,breeding,biochemical components,anthocyanin content and external influence of environmental factors about purple tea.It need to be further on biochemical mechanisms^[2-6].This paper uses the purple tea with a bud and two leaves which the leaves has been red throughout the year,as the material of the experimental group.Yinghong No.9 are used as materials for the control group,and they are sampled during different time.Through the enzyme activity and Metabolomics detection,then combain basic biochemistry and the sensory evaluation of tea products,the results of the study are as follows:1.Fresh leaves of the same tenderness in the control and experimental groups were taken,frozen in liquid nitrogen and stored in the refrigerator,and the enzyme activity were detected using the Elisa kit.The main enzyme activity in the pathway of synthesis of anthocyanin showed that the UFGT（flavonoid-3-O-glycosyltransferase）enzyme activity was significantly different between the experimental group and the control group and was closely related to the change of the content.The enzyme concentration of CHS（Chalcone Synthase）was higher in tea plants,and the correlation between other enzyme activities and anthocyanin synthesis was not significant.2.It would be detected and analyzed,including the content of the anthocyanins,amino acids.soluble sugar and total polyphenol content.At the same time,the eight components of caffeine and catechins in all the samples were tested and analyzed.The results showed that the content of anthocyanin in purple tea was generally higher than that of the control group and the highest level was 3%.The content of steamed anthocyanins was lower than that of freeze-dried samples,indicating that heating would cause loss of anthocyanin to varying degrees;the polyphenol content in two groups is generally higher,most of which are more than 30%,thaw the experimental group is generally greater than the control for the tea products.The content of catechins and caffeine was more complex between the two groups;the content of amino acids was different depending on the variety.The content of amino acids is relatively high on HY-26,which can reach about 6%;the soluble sugar content of the experimental group is generally higher than that of the control group.The results of the sensory evaluation of the tea products showed that,the tea color of the experimental group was purple and black,the tea soups were mostly purple or blue-purple.The change in anthocyanin content lead to the different flavor;the results of the sensory evaluation of black tea show that purple tea is slightly inferior to that the control group;the white tea product of the experiment group has a unique aroma,taste and sweetness.There are higher white tea fitness parameters.3.Metabolomic analysis three of the experiment group and the control group.The samples were tested in both positive and negative modes using LC-MS.Based on the detection results,differential metabolites between two groups were analyzed and found,then identify specific differential metabolites and analysis the pathway assignment of these differential metabolites.The consequents suggest that there is no difference in the content of acylated anthocyanin between the control group and the experimental group;the varieties in purple tea contain different anthocyanin components,which resulting in differences in leaf color;anthocyanin components are different during the different time.