Chemical signatures and sensory perception of Nongxiangxing Baijiu: regional and quality-grade discrimination and the modulatory role of ethanol.

This study systematically characterized the sensory and chemical features of five-grain Nongxiangxing base Baijiu across production regions and quality grades. The results showed differences in both overall sensory profiles and chemical composition between samples from the Yibin region and those from other regions. Partial least squares discriminant analysis (PLS-DA) differentiated Yibin from Non-Yibin samples and identified 29 candidate discriminant compounds. Between quality grades, compound composition also differed. Mann-Whitney U tests further identified 34 compounds with significant differences between grades, with esters and alcohols enriched in premium-quality grade samples and acids higher in normal-quality grade samples. Rate-All-That-Apply (RATA) results indicated that ethanol reduction via water dilution altered sensory profiles: although aroma-compound concentrations decreased proportionally with dilution, sensory profiles did not decrease proportionally. Overall, this study further clarifies regional and quality-grade differentiation in five-grain Nongxiangxing base Baijiu and highlights the important role of ethanol in aroma perception.