Understanding the promotion of withering treatment on quality of postharvest tea leaves using UHPLC-orbitrap-MS metabolomics integrated with TMT-Based proteomics

Withering, or “spreading” in Chinese word, is a key process in Chinese green tea production. However, the underlying mechanisms of this treatment remains unclear. To investigate the effect of withering treatment on the quality of postharvest tea leaves, UHPLC-Orbitrap-MS metabolomics and tandem mass tag (TMT)-based proteomics analysis were performed. A total of 69 metabolites were identified, and up to 136 different expressed proteins were obtained through pair-wise comparisons. Comprehensive metabolomics and proteomics analyses revealed a monotonic metabolic shift ascribed to the tea leaves’ response to dehydration stress caused by harvesting. Multiple amino acids were increased in level due to protein degradation; the biosynthesis of catechins and flavonoids were inhibited; the level of glycosidically bound volatiles were decreased attributed to the metabolism enhancement. These metabolic changes provide a material basis for later processes in green tea production and help with the quality formation of green tea.