Conclusion
The present work designed a simple but effective comparison model (Fig. 2), which provided an equal matrix for samples of TBW and CTB, and was crucial for the following sensory test and GC–MS analysis.
The results showed that both relative contents and varieties of most of the typical volatile compounds of teas were significantly different between TBWs and CTBs. Among these compounds, the concentration differences of monoterpene alkenes, jasmine lactone and aldehydes/ketones, between TBW and CTB, might be caused by absorption of hydrophobic yeast biomass (King & Dickinson, 2003), or even by evaporation during the long brewing process due to their structural properties of low polarity and low boiling point. The other typical tea volatile compounds, including methyl salicylate, indole, especially geraniol and its derivatives (Fig. 3), were modified by yeast fermentation during brewing.