GC/QQQ coupling with metabolomics for selection of predicator of tea fermentation

Fermentation is the most crucial process for manufacture of black tea. Signature components were desired for the establishment of accurate prediction of fermentation degree. In this study, finished black teas were prepared using leaves that had been fermented for various times, and sensory quality evaluation was performed. Tracking analysis of volatiles during fermentation was conducted to discriminate the iconic compounds. On the basis of both the sensory evaluation results and the enzymatic oxidation traits of fermentation, the ratio of β-cyclocitral to γ-pylpyrone was proposed as an indicator. A positive correlation was observed between this ratio and the sensory score of finished black tea with varied duration of fermentation, and the correlation coefficient was 0.78. Furthermore, widely plant-targeted metabolomics was applied to cognize the fermentation. Comparative analysis of metabolites was conducted by category, and special attention was paid to flavonoids and terpenes. Significant metabolic differences emerged discriminatively. The results would be useful for intelligent modulation of the manufacture of black tea.