不同产地扁形绿茶的品质成分差异分析

为了系统和全面地了解扁形绿茶的品质特征,分析来自湖北大悟、浙江磐安、安徽歙县、贵州湄潭、四川峨眉山5个产地扁形绿茶样品的感官品质、色差以及茶多酚、游离氨基酸、水浸出物、咖啡碱、可溶性糖等主要化学成分含量差异。结果表明,龙井茶干茶L1值(亮度值)与b1值(黄蓝色度值)分别达到38.20和19.35,均显著(P<0.05)高于其他4个产地的扁形绿茶,大方茶茶汤L3值最高。大方茶和湄潭翠芽平均水浸出物总量超过48.00%,显著(P<0.05)高于孝感龙剑茶、龙井茶及竹叶青茶。湄潭翠芽的游离氨基酸、咖啡碱、儿茶素、表儿茶素没食子酸酯、儿茶素没食子酸酯含量均最高,表没食子儿茶素没食子酸酯含量以孝感龙剑茶最高。基于各品质成分的相对含量建立的偏最小二乘法判别分析模型成功区分了5个产地的扁形绿茶样品。同时,利用偏最小二乘法判别分析变量重要性因子值筛选到11种关键成分,分别是干茶E1(综合色差值)、干茶a1(红绿色度值)、干茶b1、表儿茶素没食子酸酯、没食子儿茶素没食子酸酯、咖啡碱、游离氨基酸、茶汤a3、茶汤b3、茶汤L3、茶汤E3,可作为区分5个产地扁形绿茶的品质指标。本研究结果将为扁形绿茶加工工艺和品质提升提供一定的科学参考。

Differential Analysis of Quality Components of Flat Green Tea from Different Producing Areas

In order to systematically and comprehensively understand the quality characteristics of flat green tea,the sensory quality,color difference,and content differences of tea polyphenols,free amino acids,caffeine and water extracts from five different areas(Dawu county,Hubei province,Panan county,Zhejiang province,Shexian county,Anhui province,Meitan county,Guizhou province,Emeishan city,Sichuan province)were analyzed. Results showed that the L1 value(brightness)and b1 value(yellowness and blueness)of dry Longjing tea were 38.20 and 19.35,respectively,both significantly(P<0.05)higher than that of the other four types of flat green tea. The L3 value(brightness)of Dafang tea soup was the highest. The total amount of water extracted of Dafang tea and Meitan Cuiya tea were over 48.00%,significantly(P<0.05)higher than that of Xiaogan Longjian tea,Longjing tea and Zhuyeqing tea. The contents of free amino acid,caffeine,catechin,epicatechin gallate and catechin gallate were all the highest in Meitan Cuiya. The content of epigallocatechin gallate was the highest in Xiaogan Longjian tea. The partial least square discriminant analysis model based on the relative content of each quality component successfully distinguished the flat green tea samples from five producing areas. The variable important for the projection value(VIP>1)was used to screen 11 key quality components as quality indexes to distinguish five flat green teas,which were E1(dry tea),L1(dry tea),b1(dry tea),epicatechin gallate,gallocatechin gallate,caffeine,free amino acid,a3(tea soup),b3(tea soup),L3(tea soup)and E3(tea soup). This study would provide a scientific reference for the processing technology and quality improvement of flat green tea.