The Effects of Different Yellowing Time on the Taste Quality Components of'Pingyanghuangtang'
In order to study the differences of taste quality components of'Pingyanghuangtang'(a yellow tea)with dif-ferent yellowing time,the effects of different yellowing time on the taste quality and main components of'Pingyanghuangtang'were clarified through sensory evaluation,biochemical composition determination and chemometric analysis.The results indicated that'Pingyanghuangtang'showed different taste characteristics within a period time.The content of water extract and total amount of free amino acids in the tea samples first increased and then decreased.The mass ratio of water extract reached the maximum(54.88％),and yellow tea tasted more fresh and sweeter at 24 h yel-lowing time.The contents of total catechins,ester catechins and caffeine all decreased with the increase of yellowing time,while non-ester catechins and gallic acid increased.At the same time,the principal component analysis showed that there was a certain correlation between various biochemical components,epigallocatechin gallate,epigallocatechin,gallocatechin,caffeine and theanine had a great contribution to'Pingyanghuangtang'taste characteristic under the exper-imental conditions.It indicated that the change of taste quality in the process of the stuffiness was the result of the joint expression of various related chemical components.According to the PLS-DA model,the markable difference compounds gallocatechin,caffeine,gallic acid,epicatechin and asparagine were obtained,which can be used as index substances for directional processing of high-quality'Pingyanghuangtang'under the certain yellowing time.
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