Drying-method dictates green-tea flavor: Key odorants, OAV-based markers and precursor fate mapped by GC-MS/O and targeted metabolomics

Green tea occupies a prominent position in the Chinese tea market. Although drying the tea constitutes a critical processing step, its mechanistic impact on aroma quality remains unclear. This study aimed to investigate the effects of three drying methods—roasted drying (RD), pan drying (PD), and sun drying (SD), namely, on green tea aroma formation. Sensory molecular science and targeted metabolomic analyses indicated that PD resulted in distinct chestnut- and bean-like aromas, while SD resulted in fatty and green aromas. ( E )-2-heptenal, ( E )-2-octenal, and nonanal, characteristic of SD green tea, were found to be the key sources of fatty aroma. These compounds are typically produced by the degradation of unsaturated fatty acids such as linoleic, oleic, and palmitic acids. Conversely, 2,5-dimethylpyrazine and 3,5-diethyl-2-methylpyrazine, generated through the Maillard reaction (MR), were identified as primary contributors to the chestnut- and bean-like aromas resulting from PD. Precursor analysis (soluble sugars, free amino acids, fatty acids, and MR intermediates) substantiated these findings. This study systematically elucidates drying-driven aroma modulation mechanisms, providing a theoretical foundation for optimizing the aroma quality of green tea.