Changes in Tea Quality Components in the Yellowing Process of Wild Baiyun Yellow Tea and the Isolation and Identification of Microbial Strains
Article
Figures
Metrics
Preview PDF
Reference
Related
Cited by
Materials
Abstract:
In order to investigate the factors influencing the processing s of yellow tea from fresh leaves of wild Baiyun tea species, the main quality components of yellow tea, roasted green tea and half- baked and half-fried green tea processed from wild Baiyun tea were analyzed. The changes of culturable strains in the 8 tea samples (green tea, pan-fried green tea, rolling leaves, refried leaves (dehydrated leaves), leaves with 24 h smothering, leaves with 48 h smothering, leaves with 72 h smothering, and raw tea) withdrawn from the yellow tea processing of the fresh leaves of wild Baiyun tea were examined. The comparison of the wild Baiyun tea with the baked green tea, and the half-baked and half-fried green tea revealed that in addition to the slight decreases in amino acid and caffeine contents, the wild Baiyun tea had a higher water extract content (increased by 4.80% and 7.11%, respectively) , a higher soluble sugar content (increased by 0.41% and 0.36%, respectively), but lower tea polyphenol content and total catechin content (ester-type catechin content decreased by (21.62 mg/g and 19.08 mg/g, EGCG content decreased by 9.99 mg/g and 6.98 mg/g, and GCG content decreased by 14.23 mg/g and 13.80 mg/g, respectively). All these changes were significant (p<0.05). There were no significant changes in the contents of the non-ester catechins and the total content of non-ester catechins, except that C was reduced by 2.49 mg/g and 1.75 mg/g, respectively (p<0.05). After smothering for 24 hours, a significant number of yeast was detected, and fungi became dominant (3.5×105 CFU/g) after smothering for 72 hours. Eight microbial strains were isolated and identified, including 1 Pestalotiopsis strain, 4 Penicillium strains, 1 Cladosporum strain and 2 yeast strains, with Penicillium exsudans being isolated and identified for the first time from tea processing and tea leaves. The results indicated that smothering of tea increased the water-soluble and soluble sugar contents of tea, decreased the contents of tea polyphenols and ester-type catechins. Microbial reproduction occurred in the yellowing stage and participated in the formation of yellow tea quality.
