The Study On The Chemical Components Of Zijuan Green Tea And Its Ready-to-drink Fruit Beverage

Zijuan tea is a new specific variety of tea cultivated by Tea Research Institute,Yunnan Academy of Agricultural Science,and except for the biochemical components possessed by other kinds of tea,such as catechin,theanine and caffeine,Zijuan tea is also rich in anthocyanins,moreover,study has shown that Zijuan tea has the effects of lowering blood pressure,losing weight,reducing lipid,nourishing the stomach,slowing down liver dysfunction as well as preventing cardiovascular and cerebrovascular diseases,improving eyesight and preventing eye fatigue.In daily life,people usually drink Zijuan tea by brewing,which has made the use of the tea limited in a single way.Thus this paper will provide an analysis of the components of Zijuan tea,select material with higher anthocyanins,identify and study the stability of the anthocyanins in it,trial and choose the best extraction process as well as optimal filtration and clarification method,then analyze the mainstream fruit tea beverage,optimize the formulation of Zijuan fruit tea beverage by reference to high quality products in market,the effect of sterilization storage to the functional components in the beverage is also studied.And the main research contents and results are as follow:1.The basic components of 4 Zijuan green tea,Kenya purple tea and Yunnan common large leaf green tea was analysised,it shows that the content ranges of aqueous extract,tea polyphenol,caffeine and free amino acid in the six samples are respectively 44.19-48.83%,21.20-28.96%,2.04-3.86% and 2.99-3.70%.The content of catechin and ester catechins in Yunnan common large leaf green tea are all much higher than those in other tea samples.And main characteristics of catechin in Zijuan green tea are higher content of EGC and EC,as well as lower ECG and EGCG.The anthocyanin range of the six tea samples is0.07-1.31mg/g,and anthocyanin in Zijuan green tea and Kenya purple tea are much higher than that in Yunnan common large leaf green tea,the highest being 15 th times.By the technique of LC-Q-TOF-MS,it is determined that there are mainly four kinds of anthocyanin in the tea sample with highest anthocyanin content—Cyanidin,Delphinidin,Cyanidin-3-O-glucoside and Delphinidin-3-O-galactoside,and the contents are respectively 115.59μg/g,122.26μ g/g,699.93μg/g,265.84μg/g.From the study of stability of anthocyanin in Zijuan green tea,it can be seen that the stability is better in acid,low temperature and dark environment.2.By using conventional water extraction and citric acid extraction respectively,the effects of different extraction methods to the extraction results of Zijuan green tea are researched.The research shows that citric acid extraction has increased the content of anthocyanin in leach liquor by 17.14% compared with that in the control group.Through single factor experiment and orthogonal test,the optimal extraction condition of Zijuan green tea is 70 ℃ as extraction temperature,extraction time being 30 min,tea-water proportion being 1:60,under which condition the content of anthocyanin in the leach liquor(diluted to 1:100)is 11.38mg/L.3.In the research of optimal filtration and clarification of Zijuan green tea,the components,chromatic aberration and turbidity before and after centrifugal treatment and ceramic membrane treatment are respectively inspected.The result shows that ceramic membrane filtration is better in clarifying the leach liquor of Zijuan green tea,in which retention rates of tea polyphenol,anthocyanin,caffeine and free amino acid are all above90%,thus the ceramic membrane filtration can be used in clarification of the leach liquor of Zijuan green tea.4.By analyzing the mainstream fruit tea beverages in market,a mathematic model for evaluating fruit tea drink can thus be built,and referring to the high quality products sold in market is favorable to create the optimal formulation of camellia sinensis var.assamica green drink.Using the fuzzy mathematical sensory evaluation method and matrix model can help to figure out the fuzzy grading of each constituent,and through single factor experiment and central composite design of Box-Behnken center optimizing the formulation of Zijuan fruit tea beverage,in the best formulation,the additive amount of Zijuan green tea,crude sugar,lemon juice and apple juice concentration are respectively0.559%,7.060%,1.936% and 7.375%,under which condition the fuzzy mathematic grade is 3.462,the highest.5.By UHT sterilization,the contents of tea polyphenol,anthocyanin and free amino acid in Zijuan tea beverage are respectively declined by 8.06%,16.39% and 11.01%.The retention rate of caffeine is 98.15%,basically no change in content.The content of total catechins undergoes a relatively lower decrease,but the catechins components have changed greatly.After the sterilization,the color of product darkens slightly,less astringent in taste,and the overall integration of flavor is increased,however,the higher temperature has also changed the components of aroma,creating unpleasant stewed taste.6.By study of product appearance,p H value and components ’ stability of camellia sinensis var.assamica tea drink after being kept for a certain period respectively under the temperature of 4 ℃,25 ℃ and 37 ℃ within its storage period,the appearance of the product is stable and p H value basically has no noticeable change.The content of caffeine during the storage period is relatively stable,and the retention rates of other components are relatively high when the storage temperature is 4℃,while they decline greatly under the temperature of 37℃.So refrigeration is better for quality keeping of Zijuan fruit tea beverage.