Comprehensive metabolite profiling reveals the dynamic changes of volatile and non-volatile metabolites in albino tea cultivar 'Ming guan' (MG) during white tea withering process.

Abstract

'Ming guan'(MG), an elite albino cultivar deriving from the progeny of the traditional albino cultivar 'Bai jiguan', is a promising candidate for white tea production due to its favorable amino acid to phenol ratio. In this study, a comprehensive metabolomics analysis using ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) and headspace solid-phase microextraction-gas chromatography mass spectrometry (HS-SPME-GC-MS) were conducted to reveal the dynamic changes of non-volatile and volatile organic compounds (VOCs) throughout the withering processing of MG white tea. Meanwhile, multivariate statistical analyses were applied to screen for the characteristic components in the flavor and aroma of MG white tea. A total of 625 non-volatile metabolites and 118 VOCs were determined, of which 90 non-volatile metabolites (VIP ≥ 1, FC ≥ 2 or ≤ 0.5) were identified as key flavor components significantly changed throughout the withering process. The relative odor activity value (ROAV) analysis highlighted 22 VOCs (ROAV ≥ 1) with substantial effect on aroma formation, of which geraniol, (E)-2-hexenal, 4-methoxy-benzaldehyde and guaiacol emerging as the most key aroma constituents of MG white tea, endowing MG white tea with fruity and floral odor notes. This study offered a comprehensive investigation into metabolite changes in MG white tea, contributing valuable insights for the innovation of new white tea products utilizing albino tea plant mutants.