Characterization of the aroma-active compounds in Daqu: a tradition Chinese liquor starter

Daqu is a fermentation starter and substrate complex that is used to initiate the solid fermentations for the production of Chinese liquor. The aroma of Daqu is one of the most important factors that influence the flavor of Chinese liquor. The objective of this study was to evaluate the potent aroma-active compounds in Daqu. Odorants of Daqu extracted by solvent-assisted flavor evaporation (SAFE) were investigated by gas chromatography–olfactometry (GC–O) system with two olfactometric methods: detection frequency (DF) method and aroma extract dilution analysis (AEDA). A total of 43 compounds were identified in Daqu. Thirty-eight aroma-active components were further detected among which 33 were identified. Among these compounds, 4 odorants seem to contribute actively to the aroma of Daqu: hexanal (green grass), unknown (no.u2, nutty, roasted), phenylacetaldehyde (floral, rose) and 4-ethyl guaiacol (clove, spicy).