Study On The Dynamic Model Of Chemical Constituents And The Acceptability Of Yellow Tea

Yellow tea is one of the six major teas in China,developed from green tea processing.Special piling process created the unique quality”Yellow leaves and yellow infusion”of yellow tea.The taste is mellow and sweet characteristics of yellow tea.The yellow tea was piling at different temperatures and different water contents,The effects of piling time on the changes of color difference and chemical composition were studied,Study on sensory taste characteristics and consumer acceptance of yellow tea sold.By using zero order and first order kinetic equations,some chemical composition changes were fitted,Using descriptive analysis,correlation analysis,principal component analysis and cluster analysis for the yellow tea flavor characteristics and consumer acceptability analysis,and to explore the relationgship between the various properties and chemical composition of taste taste points,a prediction model of consumer acceptance and taste intensity attribute points are established,The main conclusions are as follows:1.In this experiment,the chemical composition and color difference of yellow tea during yellowing were measured under different water content and temperature,The results showed that tea polyphenols,chlorophyll a,total chlorophyll,total free amino acids,thearubigins,theabrownins,EGCG,ECG,a* and b* have significant differences in P < 0.05 level,reduce the total trend of tea polyphenols,b* value first increased and then decreased,the total free amino acid and thearubigin first increase then decreases and then increases,theabrownin increase first and then decrease and then increase the absolute value of chlorophyll a,total chlorophyll,EGCG,ECG,a* is gradually reduced.the high regression coefficients indicated the acceptability of the zero order reaction for Chlorophyll a,EGCG,ECG.The K(reaction rate constant)were obtained in prediction mode.It was indicated that the temperature and the time increased as the the K(reaction rate constant)of Chlorophyll a,EGCG,ECG increasing.From which Ea(activation energy)and A(frequency factor)of Chlorophyll a,EGCG,ECG were obtained,changes of chlorophyll a were most likely to occur,followed by ECG,EGCG.The higher the moisture content of the same substance,the easier it is to react in the process of yellowing.2.The sensory evaluation and acceptability analysis of 15 yellow tea and homemade yellow tea were carried out,and a small yellow tea taste description system was obtained,Describing the intensity relation of each taste in the system issweet>mellow>soft >thick >aftertaste=sweet after taste >fresh flavor> bitter>astringent>green>roasted flavours>acid>taste of water>foreign flavour,High consumer acceptance of yellow tea samples for 4,5,10,9,11,8,12,1,7,and low acceptance of yellow tea samples for the 13,2,15,14,6.The taste attributes which were significantly positively correlated with consumer acceptability were sweet,fresh,mellow,thick,soft,aftertaste,total strength.Showed significant negative correlation for bitter,astringent.Principal component analysis finally extracted two principal components to explain the total variation of sensory properties of yellow tea taste by91.407%,There is great correlation between the taste of bitter and astringent attribute points;there is correlation between the total strength,sweet and fresh;there is a large correlation between alcohol,thick,soft,aftertaste.Finally,the evaluation model of consumer acceptance is established.The evaluation model is Y=0.729*PC1+0.271*PC2.3.Descriptive statistical analysis of 34 taste indexes in 15 samples of yellow tea,the change range of taste components of yellow tea samples was obtained,among which the difference of other flavor chemical components except water extract was larger.22 kinds of main taste compounds and taste points attributes have significant correlation,significant and sweet,alcohol,fresh,soft,thick,aftertaste,the total intensity is positively related to the main soluble sugar,soluble pectin,aspartic acid,serine,glutamic acid,glycine,alanine,histidine,arginine,theanine the total free amino acids,and the bitterness and astringency was positively related mainly to tea polyphenols,caffeine,rutin,EGCG,EC,GCG,ECG,total catechins,tyrosine.Cluster analysis can classify yellow tea with similar taste and acceptability into 5 categories,which shows that cluster analysis can be used as a new method for classification of yellow tea taste similarity and classification of consumers' acceptability.The intensity prediction model of several taste attributes which is significantly correlated with consumer acceptance is constructed by PLSR,and the coefficient R2 of each latent variable model fitting is higher.The standardized regression coefficient in the model also verifies the conclusion of the correlation analysis and the accuracy of the model,It was found that the contribution of taste components to taste attributes was not unitary,but complex interaction.