Study On A Process Of Instant Green Tea And Qulity Standards System

Green tea is designated “National drink” for its effects on health.Nowadays,in most cases,people only drink brewing tea.The traditional brewing method makes tea a restricted drink,because brewing equipment are necessary for tea-drinking.In this program,High-quality and cold-instant tea powder were made from Sichuan green tea and quality standards was set up.The instant tea powder makes it very convenient for customers to drink tea.In extracting experiments,the experiment determined the level of orthogonal table by single-factor assay.Time,temperature and ratio were chosen as predominating factors and given four levels for each factor.For content of polyphenols,time is the most important factor.Next is temperature and the influence of ratio is minor.The optimal extraction condition is: 85℃,22:1,60 min.For yield of tea powder,the positions of time and temperature were exchanged.The optimal extraction condition is:80℃,22:1,60 min.Thus,the assay determined that the optimal extraction condition is:80℃,22:1,60 min.The solution is filtered by ceramic membrane,concentrated by reverse osmosis membrane and added β-cyclodextrin.The assay evaluated different concentrations of β-cyclodextrin(2%,4%,6%,8%,10%)on the quality of tea powder.The results demonstrated that 8% of βcyclodextrin can protect aroma ingredients the best.After embedding,the solution was dried in freezing temperature(-80℃).GC-MS was performed to analyze the aroma ingredients.Samples without βcyclodextrin contained 47 compounds(hydrocarbons: 29.05%,alcohols: 25.25%,esters: 3.31%,aldehydes:17.93%,ketones:4.54%,phenols: 18.65%,nitrogen-containing compound: 1.06%,acids:0.02%).Samples with 8% of βcyclodextrin contained 60 aroma ingredients(hydrocarbons: 24.12%,alcohols: 21.66%,esters: 5.26%,aldehydes:20.71%,ketones:3.10%,phenols: 10.93%,nitrogen-containing compound: 14.05%,acids:0.18%).The results showed that samples with βcyclodextrin contained 13 aroma ingredients more than negative samples.The assay determined the HPLC condition for finger-print spectrum.20 samples from different producing areas were analyzed to set up finger-print spectrum.16 peaks were found in all samples.The 11 th peak,which stood for EGCG,was chose as reference peak.The physical and chemical standards of Sichuan green tea powder were determined: polyphenols>40%,water<6%,total ash<20%,Pb<1.0mg/kg.