Flavor Profiling of Jinyu-Wan Fuxiang Baijiu: Effects of Fermentation Time and Quality Grade Analyzed via GC × GC-TOF-MS, HS-GC-IMS, and Sensory Evaluation

The flavor characteristics of Baijiu, including differences in volatile organic compounds (VOCs) and sensory evaluation, are critical for determining its quality grade, which is also influenced by the fermentation time of the grains. However, the fermentation mechanisms of most types of Baijiu remain unclear. In this study, we investigated the flavor characteristics of three quality grades of Jinyu-wan Fuxiang Baijiu (JFXB) at two different fermentation times. A high number of VOCs were revealed via two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOF-MS), while principal component analysis (PCA) and orthogonal partial least squares discrimination analyses (OPLS-DA) indicated significant VOC differences among samples. Relative odor activity value (ROAV) assessment identified 12 VOCs with ROAV > 1 that were regarded as the key aroma contributors, along with 31 key differential VOCs with variable importance in projection (VIP) values greater than 1 (VIP > 1). Headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) accurately identified 62 VOCs, establishing a VOC fingerprint and revealing 21 VOCs with VIP > 1. Sensory analysis revealed significant differences in the aroma, taste, and appearance of the samples. Overall, this study elucidates the flavor characteristics of Fuxiang Baijiu (FXB), providing valuable insights for the flavor quality control of FXB and a foundation for its fermentation process.