Novel insights into the effect of withering degree on Dianhong Congou black tea quality

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Summary Withering degrees (mild, appropriate and severe) have an important effect on the quality of Dianhong Congou black tea. In this study, appropriate withering (AW) promoted the conversion of catechins, yielding theaflavins (TFs) and thearubigins (TRs). This withering degree also resulted in the degradation of flavonoid glycosides, and the formation and conversion of soluble sugars and high‐boiling volatile compounds. The objective colour attributes were significantly higher under AW conditions, in addition to the best sensory qualities, including umami and sweetness flavours. Moreover, nine key non‐volatile compounds (TRs, theabrownins (TBs), fructose, etc.) and seven key volatile components (benzaldehyde, trans‐β‐Ionone, methyl salicylate, etc.) were determined. This research provides theoretical support for in‐depth exploration of the formation mechanism of Dianhong Congou black tea.