Insights into the Flavor Profiles and Key Aroma-Active Compounds of Sichuan Xiaoqu Qingxiangxing Baijiu Across Distilling Stages

Distillation, a crucial step in <i>Baijiu</i> production, profoundly influences its flavor. However, the aroma-active compounds of Sichuan <i>Xiaoqu Qingxiangxing</i> (<i>SXQ</i>) Baijiu during distillation remain unclear. Here, we comprehensively analyzed the volatile flavor compound (VFC) composition and alcohol content variations across three key distillation stages (i.e., head, heart, and tail) of <i>SXQ Baijiu</i> using headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS), alongside electronic nose (E-nose) and electronic tongue (E-tongue). A total of 111 VFCs, 22 key odorants, and 11 pivotal differential VFCs were identified. Ethyl octanoate were identified as the most critical odor-active compounds, while isoamylol was recognized as a key difference marker. VFC concentrations in raw <i>Baijiu</i> decreased from head > heart > tail, while VFC categories increased from tail > head > heart. The flavor profiles of the head differ significantly from those of the heart and tail in <i>Baijiu</i> distillation. Alcohol content decreased as distillation proceeded. The E-nose and E-tongue effectively distinguished raw <i>Baijiu</i> samples from different distillation stages. This study enhances our understanding of volatile compounds and their aroma contributions during the distillation process of SXQ <i>Baijiu</i>. The findings provides bases for optimizing the distillation and quality-based classification of distillates in SXQ <i>Baijiu</i> production.