Studies On The Quality And The Free Radical Scavenging Activities Of Storage Of White Tea

White tea is one kind of tea in China,which is favored by consumers.In recent years,white tea after storage more and more receives the general consumer's affection.This research used the white tea in different years which was stored in natural condition to study the quality and the free radical scavenging activities of white tea with different kinds and different product years.We used the white tea produced in the same year and stored in rapid aging condition to study the quality of white tea storage,systematically summarize the quality and the free radical scavenging activities of white tea storage,in order to provide a reference for different years white tea quality and a basis for white tea health benefits,providing guidance for white tea rational consumption.The main results are as follows:1 The quality characteristics of different white teaThe main biochemical components and color of different kinds of white tea are different.Water extract:Baimudan>Baihao Yinzhen>Shoumei;Tea polyphenols and caffeine:Baihao Yinzhen>Baimudan>Shoumei;Flavonoids and soluble sugar:Shoumei>Baimudan>Baihao Yinzhen;Amino acid:Baimudan>Baihao Yinzhen>Shoumei;TR,TB,TF:Shoumei>Baimudan>Baihao Yinzhen;L*,a*,b*:Shoumei>Baimudan>Baihao Yinzhen.As the level of fresh leaves reduced,the color of dry tea,leaves became red and yellow.Taste of Baimudan was the strongest convergence,Shoumei was the weakest,Baihao Yinzhen was pure and mild.The aromatic components in different kinds of tea were different.The content of lcohol was thehighest in different kinds of white tea and the percentage of that was 60.64%,51.26%,46.30%in Baohao Yinzhen,Baimudan,Shoumei,respectively.Linalool,geraniol,methyl salicylate,linalool oxide,benzaldehyde,phenylethyl alcohol are the material basis of pekoe flavor of White tea.The alcohols,such as linalool,geraniol was the highest in Baihao Yinzhen,while alpha-ionone,beta-ionone,geranylacetone were higher in Shoumei.2 The quality characteristics of white tea produced in different yearsBased on the analysis of sensory quality,major biochemical components and aromatic components of white tea produced in different years,we got the following results:As the extension of storage time,biochemical composition and color of white tea are different from new white tea changed.The water extract,tea polyphenol,amino acids,L*values in Baihao Yinzhen,Baimudan,Shoumei declined,while Flavonoid,TR,TB,a*,b*increased.Content of the caffeine,soluble total sugar fluctuated,caffeine and soluble sugar content wasrelatively stable,TF showed no obvious regularity.With the extension of storage time,the color of the dry tea,the tea,the leaves of the white tea changed to dark,yellow,red and clear fresh crisp aroma was waning,aged fragrant emerged,and the taste became pure and mild.The aroma components in white tea changed a lot during in the process of storage.Clear fresh crisp aroma was waning,aged fragrant emerged.With jujube sweet plum incensed fragrance,etc.After storage,the alcohol content reduced about 8.36%to 29.40%and hydrocarbon content increased 6.83%to 34.39%.Percentage of Linalool,linalool oxide,geraniol,methyl salicylate,phenylethyl alcohol,nerolidol,and geranial was reduced in the aged White tea,while gedrol,dihydroactinolide,naphthalene,2-methyl-gedrene,beta-gedrene,were increased.These aromatic components together with benzaldehyde,alpha-ionone,beta-ionone,geranylacetone made the aroma characteristic of aged White tea.3 The influence of rapid aging conditions on white tea storage qualityUnder the condition of room temperature,25?,35?,45? and initial moisture content of 7%,9%,12%,a certain time of storage can turn the quality of new white tea into old white tea.In the condition of room temperature and 25?,initial moisture content of 7%,9%,the change of tea was little,but when initial moisture content was 12%,the tea got mildew.In the condition of 35?,45?,the color of Baimudan changed to Sepia and Shoumei changed to rust.The higher the temperature and the initial moisture content,the more obvious changed.At 35?,clear fresh crisp aroma was waning,aged fragrant is emerging.At 45?,the taste turned acid.The best condition is 9%-35?.Under the condition of rapid aging,biochemical composition of white tea changed after storage.The water extract content,tea polyphenols,and amino acid decreased.Caffeine content in the process of storage was stable.4 The differences of white tea quality between storage in Rapid aging and natural aging conditionArtificial and natural conditions of white tea storage are similar.The content of water extract,tea polyphenols,amino acids cut down and the content of caffeine was stable.Storaged white tea has similarities and differences in Sensory quality evaluation between different conditions.The color of Baimudan in rapid aging under the conditions of storage was uniform.The color of Shoumei was more close to natural conditions.After 9 months,storage,the quality of white tea at 9%-35? is best.The amora of white tea in rapid aging condition is close to natural aging condition,but the amora was short.The bitterness of Baimudan tea didn't decrease after storage.Shoumei in rapid aging condition was close to natural condition.So Shoumei is more suitable to be stored in rapid aging condition.5 The ability of scavenging free radicals of white teaThe screened 65 white tea samples with different assortment and different years were analyzed.White tea has a strong ability of scavenging free radicals.The correlation of different kinds of white tea produced in different years and the free radical scavenging activities were studied by correlation coefficient,scatter plot and cluster analysis method.The results showed that the free radical scavenging activities of Baihao Yinzhen and Baimudan was stronger than Shoumei and tea cake.The effect of different white tea on the free radical scavenging activities reached very significant level.The correlation coefficient between different kind of white tea and remove DPPH free radical ability was 0.814 and which remove ABTS free radical ability was 0.752.The effect of the year of production on the free radical scavenging activities reached significant level.The correlation coefficient between productive year and remove DPPH free radical ability is-0.250 and which remove ABTS free radical ability is-0.271.6 The relation between white tea mainly biochemical components and the ability of scavenging free radicalsBased on correlational analysis,we got the result:tea polyphenol,aqueous extract,amino acid have the high correlation coefficient.Based on path analysis we got the formula:Y1(DPPH)=0.139-0.002X1-0.005X3-0.001X8,Y2(ABTs)=0.097-0.001X1-0.002X2-0.004X3-0.002X5.X1:tea polyphenol,X2:amino acid,X3:caffeine,X5:flavonoid,X8:b*.