Dynamics of biochemical components in brewing process of brewed sour tea

ObjectiveChange trend of biochemical components in brewing process of brewed sour tea was investigated, in order to provide theoretical basis for optimizing brewing process of brewed sour tea. MethodFresh coarse-old tea leaves were cleaned with water and dried in the air;300 g cleaned tea leaves and 2.5 L cooled boiled water was loaded into pick-le jar; 5,10,15,20,25,30,35 or 40 g sucrose(No.1-No.8) was added into every pickle jar,and the neck of pickle jar was covered with water; eight pickle jars were placed in the shade for fermentation,with fresh cabbage(No.9) as control. Contents of nitrite,tea polyphenol and theanine in brewed product and pH value of brewed liquid were determined every seven days. ResultResults showed that,the nitrite contents of all brewed products in eight treatment groups and control group decreased with extension of brewing time in the brewing process of brewed sour tea. Furthermore ,pH value of brew-ing liquid decreased with increasing of sucrose amount,and was basically stable after 14 d. Except No.6 and No.8,the tea polyphenol contents of all brewed products in other treatment group declined with extension of brewing time. In addition , tea polyphenol contents of all brewed products in treatment group and control group showed fluctuating decrease with ex-tension of brewing time,and increased with increasing of sucrose amount. Nitrite content and pH value of all brewed prod-ucts in No.6(adding 30 g sucrose) was the lowest among all treatments at 21 d after brewing, but tea polyphenol con-tent and theanine content were the highest,showing the best brewing effect. Nitrite content in brewed product were signifi-cantly negatively correlated with brewing time and sucrose amount,theanine content were significantly positively correlated with brewing time and sucrose amount. pH value of brewed liquid were significantly negatively correlated with tea polyphenol content(P<0.01,the same below),and significantly negatively correlated with theanine content(P<0.05,the same below). There was significantly positive correlation between tea polyphenol content and theanine content,and there was extremely significantly negative correlation between sucrose amount and pH value of brewed liquid ,but sucrose amount was extremely significantly positively correlated with tea polyphenol content in brewed product. ConclusionThe optimal brewing process of brewed sour tea is as follow:coarse-old tea leaves are added to cooled boiled water at 1∶8.3 of material-liquid ratio,and after adding sucrose at 10∶1 of material-sucrose ratio,coarse-old tea leaves are brewed for 21 days. Tea polyphenol and theanine content of obtained brewed sour tea do not obviously decrease,and nitrite content is low,there-fore,brewed sour tea is a kind of characteristic drink with high nutritional value and market potential.