Characteristic aroma compounds in naturally withered and combined withered γ-aminobutyric acid white tea revealed by HS-SPME-GC-MS and relative odor activity value

To improve the product quality in the development and processing of γ-aminobutyric acid (GABA) white tea. In this study, HS-GC-MS and relative odor activity value were employed to comprehensively compare and analyze the flavor-active compounds of GABA white tea processed by natural withering and combined withering. Compared with natural withering, combined withering significantly increased the total content of volatile compounds in GABA white tea. Among the 131 detected volatile compounds, 88 compounds were increased, while only three compounds were decreased by combined withering. In addition, combined withering was more conducive to the formation of floral and sour-fruity aroma than natural withering. It was for the first time found that 2-heptanol is the greatest contributor to the aroma of GABA white tea, followed by linalool and geraniol. Hence, 2-heptanol, linalool, geraniol, d-dipentene, methyl salicylate could be identified as the potential markers for the aroma of combined withered GABA white tea. Further analysis revealed that the metabolic pathways of terpenoid backbone biosynthesis and amino acid-derived compounds were enriched in combined withered GABA white tea, which may contribute to the formation of floral and fruit aroma. The findings of the present study may provide important guidance for the development and optimized processing of white tea.