Flavor Profile of Base Liquor Fermented by Bacillus subtilis in Daqu and the Aroma Perception Mechanism of Its Characteristic Components

This study employed sensomics, multivariate statistical analysis, and molecular docking to analyze the aroma profiles of base liquors fermented by five Bacillus subtilis strains isolated from high-temperature Daqu and the perception mechanisms of their key flavor compounds. The results showed that base liquor fermented by each B. subtilis strain exhibited a stable aroma profile dominated by Jiang-flavor and sweet notes. A total of 60 major volatile flavor compounds were identified and quantified across all five samples, the most abundant of which were heterocyclic compounds, acids, and carbonyl compounds. Ten compounds, including guaiacol, 4-ethylguaiacol, and 4-vinylguaiacol, were closely associated with Jiang aroma, while nine compounds, such as acetoin and tetramethylpyrazine, were strongly linked to sweet aroma. Additionally, acids and guaiacol were identified as compounds that significantly contributed to the characteristic aroma of B. subtilis-fermented base liquor. Hydrogen bonds and hydrophobic interactions were found to be key driving forces in stabilizing the complexes formed between aroma compounds and olfactory receptors. This study provides new insights into the contributions of functional microorganisms and their key metabolic compounds to liquor flavor and offers a theoretical foundation for the targeted application of functional strains and the development of novel liquor products.