Elucidation of Grassy Off-Odor Formation in Wuyi Rock Tea Processed from Dew-Soaked Leaves via GC–MS, Molecular Docking, and Sensory Evaluation

Wuyi rock tea (WRT) processed from dew-soaked leaves is often characterized by a pronounced grassy off-odor defect. However, the key odor-active compounds and their potential underlying mechanisms remain unclear. In this study, quantitative descriptive sensory analysis, GC-MS, GC-O, molecular docking, and aroma addition tests were used to systematically elucidate the chemical basis and potential perceptual mechanisms of the key grassy off-odor in WRT processed from dew-soaked leaves. The results showed that 16 volatile compounds were significantly associated with dew, among which (E,E)-2,4-heptadienal, octanal, hexanal, and heptanal were identified as the major odor-active compounds responsible for the grassy off-odor. The accumulation of these aldehydes may be associated with lipid peroxidation under the influence of dew. Aroma addition and omission tests confirmed that (E,E)-2,4-heptadienal contributed significantly to grassy off-odor formation and that additive effects existed among the four compounds. Molecular docking predicted that the four key odor-active compounds interacted with human olfactory receptors, including OR1A1 and OR10J5, through hydrogen bonds and hydrophobic interactions, thereby affecting grassy off-odor perception, with predicted binding energies below -4.7 kcal/mol. This study elucidated the effects of dew on the formation of the characteristic aroma of WRT and provides a scientific basis for tea quality regulation and processing improvement.