Aroma formation and dynamic changes during white tea processing.

The formation of and dynamic changes in aroma during white tea processing have not previously been systematically investigated. In this study, advanced comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry was employed to investigate the mechanism of white tea aroma formation. A total of 172 volatiles were identified and mainly comprising endogenous volatiles, which displayed diverse change trends during the withering period. In this process, free aroma precursor amino acids and glycosidically bound volatiles (GBVs) were found to contribute to the formation of white tea aroma, with the differential expression of aroma-related key genes accounting for various accumulation of endogenous volatiles and GBVs. In addition, the drying was also shown to play an important role in the formation of white tea aroma. Our study provides the first characterization of white tea aroma formation and establishes a theoretical basis for quality control during white tea processing operations.