Processing And Process Parameters Optimization And Quality Analysis With Black Tea In Different Seasons Of Baohong

Baohong tea is mostly produced as green tea,and its green tea process research is mature,but there is no standard process for black tea yet.In this paper,an orthogonal experiment was set up to optimize black tea processing parameters using fresh leaves of Baohong tea in different seasons to investigate the best processing parameters of Baohong black tea in different seasons in order to improve its quality and develop flavor-rich products.Sensory evaluation,conventional biochemical composition analysis,high performance liquid chromatography analysis and electronic nose technology were used to analyze the quality of the trial samples of Baohong black tea in different seasons;at the same time,the trial samples processed by the best process in different seasons were compared with the commercially available tea samples,and the biochemical quality components of the two were comprehensively evaluated by multivariate statistical analysis.The main results of the study were as follows:1.The results of the orthogonal test based on the total score of sensory evaluation showed that the best combination of process parameters of Baohong black tea in different seasons was A₅B₁C₂（A5:withering time of 16 h,B1:fermentation time of 2 h,C2:full drying temperature of 65℃）,so the long withering,light fermentation,full drying and slow roasting at low temperature was conducive to the production of Baohong black tea with rich floral aroma and sweet,mellow and refreshing taste;The total sensory evaluation scores of spring,summer and autumn were 93.10,94.05 and 93.60,with the highest score of the trial sample in summer.2.The results of the best trial samples of Baohong black tea in different seasons showed that the spring,summer and autumn Bao Hong black tea trial samples of aroma and taste are floral,sweet and mellow and crisp.There was no significant difference in the tea polyphenol content between the best trial samples of Baohong black tea in spring and summer,and the tea polyphenol content of the best trial samples in autumn showed a significant difference（p<0.05）.The water extract,amino acid,caffeine,soluble sugar,total catechin,non-ester type catechin,ester type catechin content and total flavonol of the three seasonal trial samples all showed significant differences（p<0.05）.3.The results of the study on the best trial samples of Bao Hong black tea in different seasons and the commercially available tea samples show that the sensory evaluation of the tea is generally characterized by a firm and haired appearance,,brown and uniform,the soup color was orange-red and bright,the leaf bottom was red-brown and uniform,and the taste of the best trial sample was sweet,mellow and fresh with rich floral aroma,which was significantly better than that of the commercially available tea samples with still mellow taste and less pure sweet aroma.The mean contents of water extracts,amino acids,tea polyphenols and theaflavins of the trial sample were 45.96%,3.17%,11.31%and0.45%,which were higher than those of the commercially available tea samples of 43.05%,2.37%,7.75%and 0.22%;the mean contents of thearubigins,soluble sugars and teabrownins of the trial sample and the commercially available tea samples were 6.54%,3.50%,6.97%and 9.03%、4.59%、8.21%,lower levels of the former than the latter.The mean caffeine content of the two was 4.41%and 4.19%,with no significant differences.The mean contents of total catechin,non-ester type catechin and ester type catechin were120.05 mg/g,55.36 mg/g and 26.60 mg/g,the mean contents of total catechin,non-esterified catechin and esterified catechin in the commercially available tea samples were 68.53 mg/g,19.74 mg/g and 8.60 mg/g,showing significant differences（p<0.05）,with the former content being higher than the latter.The mean contents of quercetin,rutin,kaempferol and myricetin were 0.07 mg/g,3.28 mg/g,0.06 mg/g,0.82 mg/g and 0.40 mg/g,1.00 mg/g,0.20 mg/g,0.57 mg/g,which were significantly different（p<0.05）.4.In the discrimination of tea broth by electronic nose technique,both PCA and LDA analysis could categorize and distinguish the aroma of the trial samples from the commercially available tea samples,and Loadings analysis showed that the aroma of both was mainly related to substances such as W5S（nitrogen oxides）and W2W（sulfides）.The multivariate statistical analysis methods were all able to clearly distinguish the best trial samples processed in different seasons of Bao Hong black tea from the commercially available tea samples,indicating that there were significant differences in the main quality components between the two.To sum up,the trial taste of baohong black tea processed in different seasons is sweet,mellow and fresh,which is obviously better than the market tea samples.Therefore,it is suggested that baohong tea processed into black tea can be used by long time withering,light fermentation,dry drying and low temperature.