| Food sciences |
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| Infusion color and taste characteristic of Dafo Longjing tea processed from different cultivars |
| XU Pengcheng1, FAN Fangyuan1, LU Debiao2, JIN jing2, GONG Shuying1* |
(1. Institute of Tea Science, Zhejiang University, Hangzhou 310058, China;
2. Zhejiang Agriculture-Technology Extension Center, Hangzhou 310020, China) |
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Abstract Dafo Longjing tea, as one of top ten famous teas in Zhejiang Province, is mainly produced in Xinchang County and popular with consumers because of its fresh-tender aroma and soft-mellow taste. It is significantly different from other kinds of Longjing teas including famous Xihu-Longjing tea, and occupies large market share; however, studies on quality features and related components of Dafo Longjing tea are rather few at present. In order to delve deeply into the mechanism of quality formation of Dafo Longjing tea, systematic analyses of correlation between liquor-taste properties and chemical constituent were performed in this study.
Dafo Longjing teas were processed by traditional processing procedure with fresh leaf from cultivars “Zhenong 113”,“Pingyang- tezao tea”,“Yingshuang”,“Longjing 43”,“Jiaming 1”,“Cuifeng”,“Baiye 1” and “Jiukeng”. The quality of the made teas was assessed by sensory evaluation, which showed that all of the samples made from different cultivars were accorded with the typical characteristic of flat, straight and bright appearance. The overall qualities of samples from“Longjing 43”,“Yingshuang” and “Jiaming 1” were superior to others, with the score of 94.80, 94.50 and 94.50 respectively. Characteristic constituents in tea samples were determined by high performance liquid chromatography. The result indicated that the“Jiukeng” and “Cuifeng” were with high content of catechins, and “Longjing 43” was with high content of gallic acid, and “Baiye 1” was with high content of amino acids. Flavonol glycosides, as essential functional ingredients with low content, were different in content among all the eight tea cultivars.
As color indicators and representative of light-dark, red-green and yellow-blue degree respectively, values of L, a, and b were read to analyze the color difference of tea infusion. The result combined with sensory evaluation suggested that Dafo Longjing tea with high brightness and moderate yellow-green degree had good quality. What’s more, the result of tea infusion color difference analysis showed significant correlation with sensory evaluation, indicating that liquid quality of Dafo Longjing teas could be quantitative description by color indicators. Taken chemical determination together with color indicator analysis, we found that flavonol glycosides, especially myricetin glycosides and quercetin glycosides, had a significant impact on liquid color quality. Signal factor evaluation of taste characteristics could make sensory concept concretely and vividly, helping to understand product’s features. In this study, taste factors of umami, sweet, bitter, astringent and kokumi were scored by sensory experts. The result showed that bitter and astringent as important factors were speculated to have significant impact on taste quality of Dafo Longjing tea. In combination with quantitative analysis of chemical constituents, we found that flavono glycosides were significantly correlated with taste factors of bitter, astringent and kokumi.
Above all, color-indicator determination and signal factor evaluation can make sensory description of liquid and taste concretely and vividly. Moreover, flavonol glycosides as important chemical constituents have significant impact on liquid and taste quality, though with low content in Dafo Longjing tea. In the future, studies on the interaction between flavonol glycosides and other components will be explored further to illuminate the function mechanism of characteristic flavor.
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Received: 22 September 2016
Published: 23 November 2016
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Corresponding Authors:
shuygong@zju.edu.cn
E-mail: shuygong@zju.edu.cn
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不同品种大佛龙井茶的汤色与滋味属性特征
通过对“浙农113”、“平阳特早茶”、“迎霜”、“龙井43”、“嘉茗1号”、“翠峰”、“白叶1号”、“鸠坑群体种”8个品种加工的大佛龙井茶进行感官属性量化描述、品质成分定量检测及两者间的相关性分析，深入探究大佛龙井茶汤色与滋味的特征属性。结果表明，“龙井43”、“迎霜”和“嘉茗1号”的综合感官品质较优。色差分析结果表明，亮度高、黄绿度适中的大佛龙井茶汤品质较高，且杨梅素苷类和槲皮素苷类物质与大佛龙井茶汤色泽有显著相关性。在滋味属性因子中苦度及涩度与大佛龙井茶汤滋味有显著相关性，而厚度滋味的感受是对单独味觉的补充，可能会对茶汤风味起到至关重要的作用。不同品种大佛龙井茶的滋味成分含量差异显著，鲜味氨基酸与鲜度呈显著正相关，咖啡碱、表没食子儿茶素、表没食子儿茶素没食子酸酯、没食子儿茶素没食子酸酯和杨梅素苷类与苦度、涩度呈显著正相关，与甜度呈显著负相关。黄酮苷类物质虽然在茶汤中含量较少，但表现出与大佛龙井茶汤色和滋味属性较为显著的相关性。
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