Process-Driven aroma Profiling: Decoding the temporal dynamics of aroma constituents in Niulanshan Erguotou Baijiu across divergent processing techniques

The formation and evolution of aroma compounds during fermentation are fundamental to defining the sensory profile of Baijiu; however, the underlying dynamics remain poorly understood. Here, we systematically investigate temporal variations in volatile compounds throughout fermentation under two distinct Baijiu production processes—Qingzheng Qingcha and Hunzheng Xucha—using gas chromatography–ion mobility spectrometry. Notably, volatile compound enrichment peaked at day 13 in Dacha Jiupei (DC), day 5 in Ercha Jiupei (EC), and day 3 in Xucha Jiupei (XC). Gas chromatography–olfactometry–mass spectrometry further revealed 37, 39, and 33 aroma-active compounds in Dacha liquor, Ercha liquor, and Xucha liquor, respectively. Remarkably, isopropyl myristate was identified for the first time in light-flavor Baijiu. Linear discriminant analysis effectively classified fermentation samples from DC, EC, and XC, achieving accuracy rates of 78.57%, 78.57%, and 57.14%, respectively, highlighting isopropyl myristate and phenylacetaldehyde as robust discriminative markers across all fermentation stages. This work provides deeper insights into the temporal evolution of aroma components, advancing our understanding of flavor development mechanisms in Baijiu fermentation. • Distinct brewing processes showed stage-specific enrichment of aroma compounds. • Isopropyl myristate was detected for the first time in light-flavor Baijiu. • LDA effectively distinguished fermentation stages and recognized key markers. • Isopropyl myristate and phenylacetaldehyde were identified as classification markers.