Characterization of key odorants causing the roasted and mud-like aromas in strong-aroma types of base Baijiu

The roasted and mud-like aromas in Chinese strong-aroma types of base Baijiu (base SAB) and the interactions among the corresponding key compounds causing these two characteristic aromas were investigated. A total of 68 and 64 odorants were identified in the base and commercial SAB by comparative aroma extract dilution analysis. Furthermore, the complex matrix of Baijiu always pose a long-term challenge for quantitative accuracy and precision of target aroma compounds; thus, the odorants with flavor dilution (FD) ≥ 9 were further quantified by multiple quantitative techniques, including the direct injection combined with gas chromatography-flame ionization detector, the vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction (VSLLME) combined with GC-MS, and the derivatization method combined with VSLLME-GC-MS, and 37 and 26 odorants were shown to be important odorants as their OAVs ≥1. Among these components, 5 compounds, hexanoic acid, butyric acid, p-cresol, 3-methylindole, and 3-(methylthio)propanal showed higher OAVs in base than in commercial SAB, and based on aroma recombination and omission analysis, they were confirmed to be the key odorants responsible for the mud-like and roasted odors. The evaluation of the aforementioned five key odorants by the "addition" test showed that the roasted and mud-like aromas of base SAB were related, and the odors were mainly attributed to additive or masking effects among the compounds.