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

Distillation, a crucial step in Baijiu production, profoundly influences its flavor. However, the aroma-active compounds of Sichuan Xiaoqu Qingxiangxing (SXQ) 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 SXQ Baijiu 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 Baijiu 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 Baijiu distillation. Alcohol content decreased as distillation proceeded. The E-nose and E-tongue effectively distinguished raw Baijiu samples from different distillation stages. This study enhances our understanding of volatile compounds and their aroma contributions during the distillation process of SXQ Baijiu. The findings provides bases for optimizing the distillation and quality-based classification of distillates in SXQ Baijiu production.