Macro-composition quantification combined with metabolomics analysis uncovered key dynamic chemical changes of aging white tea

It is a common belief in China that aging could improve the quality of white tea. However, the stored-induced compositional changes remain elusive. In this study, ten subsets of white tea samples, which had been stored for 1-, 2-, 3-, 4-, 5-, 6-, 7-, 10-, 11- and 13- years, were selected. Macro-compositions were quantified firstly. As the results showed, it was interesting to find total flavonoids, thearubigins (TRs), and theabrownines (TBs) increasing, accompanied with a gradual decrease of total polyphenols, which suggest a conversion of phenolic component in the aging process. Then, nontargeted metabolomics was further conducted on selected subsets of samples, including 1-, 7- and 13- years stored to profile their conversion. As a result, most different metabolites were related to flavonol glycosides and flavone glycosides, suggesting dynamic phenolic component changes were vital in aging. The partial least-squares-discriminant analysis (PLS-DA) also identified them as markers in distinguishing.