Analysis of Active Ingredients and Taste Characteristics of Yongchuan Xiuya

To provide a theoretical basis for the quality positioning, characteristic index screening and brand building of different grades of Yongchuan Xiuya, the active ingredients, color and taste performance of different grades of Yongchuan Xiuya products were analyzed. In this paper, the active ingredients’ content and L^*, a^*, b^* color indexes of different grades of Yongchuan Xiuya products were detected, and the relationship between the characteristic indexes and grades was studied by principal component analysis (PCA); the taste characteristics of Yongchuan Xiuya products were analyzed by electronic tongue combined with sensory evaluation. The results showed that the active ingredients’ content of Yongchuan Xiuya product showed a certain trend with the change of product grade. It showed that with the decrease of product grade, the contents of tea polyphenols, water extracts and the ratio of phenol to amino acids were increased, while the contents of amino acids were decreased. And catechin (GC), epigallocatechin (EGC), catechin (C) content increased with the decrease of product grade. Four principal components were extracted by PCA analysis. And 16 characteristic indexes that have important contribution to quality were selected, including color indexes like dry tea L^*, a^*, b^* value, fused leaf L^*, b^* value, chlorophyll a, chlorophyll b and total chlorophyll, and also tea polyphenols, amino acids, water extract, gallic acid (GA), GC, EGC, C, caffeine (CAF). And the score of PCA was opposite to the actual product grade ranking. The comprehensive score from high to low was: Level 6>Level 5>Level 4>Level 3>Level 2>Level 1. The taste of Yongchuan Xiuya with electronic tongue showed that with the decrease of product grade, the index values of sour taste, bitter taste and astringency gradually decreased, while the taste and richness increased. The three indexes include astringency aftertaste, umami and richness of electronic tongue had a extremely significant or significant negative correlation with the taste score and comprehensive score of reviewers (P<0.01, P<0.05). And the correlation coefficients with the taste score were −0.968, −0.897 and −0.956, respectively; the correlation coefficients with the total score were −0.964, −0.885 and −0.950, respectively. The grade of Yongchuan Xiuya can be well predicted by PCA evaluation index model and electronic tongue taste performance.