Changes of phenolic compounds of tea leaves during Oolong tea process

Abstract

It was believed that provided photographs of changes of total polyphenols (TPP), tannin, theaflavins (TF), thearubigins (TR) contents and total colour liquids. Green tea leaves were going through the stages: fresh tea → withering → incubated 1 → aromatic spin 1 → incubated 2 → aromatic spin 2 →fried inactivated enzymes. Tea samples in the stages were provided by Cau Tre tea factory. Tea samples were divided into two groups: the activated and inactivated enzyme groups – microwave was applied to treated the activated enzyme one. Tea samples after the inactivation were conducted. The results showed that TPP and tannin contents generally decreased. Changes of theaflavin contents were contrast to tannin contents. On the other hand, theaflavin and thearubigin are the major polyphenols that determine on the quality of Oolong tea.

Widely targeted metabolomics analysis reveals the formation of nonvolatile flavor qualities during oolong tea manufacturing: a case study of Jinguanyin

“…Combined with the results of the metabolic pathway analysis, it was found that the contents of xanthine, 7-methylxanthine, 1,7-dimethylxanthine, theobromine, and 3-methylxanthine in the caffeine metabolism (Ko00232) pathway increased significantly after turning-over, indicating that the turning-over process is potentially beneficial to the synthesis of caffeine precursors. However, there were no significant changes in caffeine, which is in agreement with the previous conclusions that caffeine variation in oolong tea processing was not significant ( 48 , 49 ).…”