Hot-air full drying driven metabolome changes in white tea (Camellia sinensis L.)

Abstract

White tea (Camillia sinensis L.) is the least processed tea, and due to simpler processing steps involved, its flavor and nutritive compound composition is least disturbed. However, only a limited number of research has explored the key metabolomic changes during white tea processing (especially drying). The freshly harvested leaves of C. sinensis var. Tieguanyin were initially withered at room temperature for 72 h, and first-dried on fire at 70°C for 3 h. Then, they were spread at room temperature for 7 days and fully dried at 80°C for 4 h, followed by cooled at room temperature. The metabolome of the tea leaves before (CK) and after full drying (RO) were compared using UPLC-MS/MS. The LC-MS/MS analysis identified 1,253 compounds belonging to 11 classes. The highest number of accumulated compounds belonged to flavonoids, phenolic acids, and lipids. Of the 57 differentially accumulated metabolites (DAMs), 49 were up-accumulated in RO. These were classified as amino acids derivatives, lipids, organic acids, vitamins, alkaloids, nucleotides and derivatives, flavonoids, tannins, terpenoids, lignans and coumarins. We found that several health beneficial compounds showed up-accumulation in RO compared to CK. We concluded that Hot-air full drying alters white team metabolome composition.