Key odorants driving aroma transformation during aging process in Liubao tea: A sensory and chemical perspective

Liubao tea, a representative Chinese dark tea, undergoes significant aroma quality changes during aging, though the precise mechanisms remain unclear. This study employed an integrated approach combining stir bar sorptive extraction-gas chromatography-mass spectrometry (SBSE-GC-MS), gas chromatography-olfactometry (GC-O), odor activity value (OAV) calculation, aroma addition experiments, and multivariate statistical analysis to investigate volatile profile variations and identify key odorants during a 6-month aging process. The research identified 84 volatile compounds, including geosmin and intermedeol-rarely reported in dark tea-and established 4 key odorants closely linked to Liubao tea's flavor quality. The findings revealed that 3,4-dimethoxytoluene and 1,2-dimethoxybenzene contribute to the "stale" aroma, geosmin primarily drives the "earthy" odor, while the attenuation of "smoky" odor correlated strongly with the decreasing concentration of 3,4,5-trimethoxytoluene during aging. These findings provide new insights into the chemical basis of Liubao tea and offer practical guidance for quality control and targeted flavor modulation in tea production.