绿茶滋味品质的定量分析及其相关性评价

Quantitative analysis and correlation evaluation on taste quality of green tea.

分析48个绿茶的7种感官滋味类型的主要化学成分含量及组成,利用各化学成分与品质间的相关性,建立茶叶品质与化学成分间的线性回归方程;通过滋味分属性评定,对各个属性与化学成分进行相关性分析,以揭示绿茶滋味类型差异性形成的物质基础。结果表明:涩的绿茶表现出高水浸出物、高茶多酚、高酯型儿茶素及高表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)含量的现象;浓的绿茶表现出高水浸出物现象;醇、甘爽的特征与较低的水浸出物、较高的氨基酸含量相关。采用逐步回归建立的品质评分与成分间的线性方程均有效,滋味评分与总分的预测合格率分别为79%和83%。滋味分属性醇度、甘度和浓度与水浸出物、EGCG、咖啡碱、没食子酸儿茶素没食子酸酯(gallocatechin gallate,GCG)、表儿茶素没食子酸酯(epicatechin gallate,ECG)、茶多酚这6种化学成分含量的相关性较强.

Summary There are many of green teas with different characteristics in China , and their qualities are often evaluated by sensory evaluation without quantifying chemical compounds . Though sensory characteristics are identified quickly , the contents of compounds are unknown . Determination of chemical compounds is usually used for tea quality evaluation and the results are relatively accurate and objective . But most of the studies focus on analyzing chemical compounds of a single flavor type . Reports about comparison of main compounds in different taste types are rare . So the chemical compounds of different taste types of green tea were quantified and their relationships with the taste quality were analyzed in this study to understand the material basis of formation of different taste types in green tea . Forty‐eight typical green teas in seven different taste types were selected from 287 tea samples by sensory evaluation . Thirteen chemical factors including tea polyphenols , amino acids , water extract , and caffeine were determined by standard methods . The relationships between compound contents and the taste quality were analyzed using SPSS （ statistic package for social science） 16 .0 software , and the tea quality predicting model based on the chemical compounds was established , which can provide certain methods for judgment of tea quality . Furthermore , the degree of correlation between every property and chemical components was carried out .The results indicated that the ester catechins , especially epigallocatechin gallate （ EGCG ） had a great contribution to the astringency . The green tea samples with astringency were of the high contents of water extract , tea polyphenols , ester catechins and EGCG . The green tea samples with strong taste were of high content of water extract . And the green teas with tastes of mellow , sweet and brisk were related to the low content of water extract and high content of amino acids . The factors of total water extracts , EGCG , gallic acid （ GA ） , caffeine and gallocatechin gallate （ GCG ） showed stronger correlation with tea quality . The equation based on stepwise regression analysis had good predictive ability for the taste quality and total quality , and the right ratios for taste score and total quality score were 79% and 83% respectively . Furthermore , the water extract , EGCG , caffeine , GCG , epicatechin gallate （ ECG） and tea polyphenols were well related to the divided taste properties .In conclusion , different kinds of taste characteristics are based on different contents of chemical components in green tea .