乌龙茶生产过程中挥发性成分吲哚的形成 | Formation of Volatile Tea Constituent Indole During the Oolong Tea Manufacturing Process
Indole is a characteristic volatile constituent in oolong tea. Our previous study indicated that indole was mostly accumulated at the turn over stage of oolong tea manufacturing process.
turn over stage of oolong tea manufacturing process是什么阶段？
(1) How is indole formed in tea leaves? indole在茶叶中是如何形成的？
(2) Why does indole accumulate at the turn over stage of oolong tea manufacturing process?
(3) Why does wounding stress lead to the difference of indole accumulation between oolong tea and black tea?
In this study, one tryptophan synthase α-subunit (TSA) and three tryptophan synthase β-subunits (TSBs) from tea leaves were isolated, cloned, sequenced, and functionally characterized.
Combination of CsTSA and CsTSB2 recombinant protein produced in Escherichia coli exhibited the ability of transformation from indole-3-glycerol phosphate to indole.
CsTSB2 was highly expressed during the turn over process of oolong tea.
Continuous mechanical damage, simulating the turn over process, significantly enhanced the expression level of CsTSB2 and amount of indole.
These suggested that accumulation of indole in oolong tea was due to the activation of CsTSB2 by continuous wounding stress from the turn over process.
Black teas contain much less indole, although wounding stress is also involved in the manufacturing process.
Stable isotope labeling indicated that tea leaf cell disruption from the rolling process of black tea did not lead to the conversion of indole, but terminated the synthesis of indole.