Comparative analysis of flavor characteristics of two rounds of Qingxiangxing Baijiu by GCxGC-TOFMS, HS-GC-IMS, GC-E-nose and E-tongue

The fermentation rounds in the brewing process of Qingxiangxing Baijiu (QXB) significantly influence its quality and flavor. This study investigates the flavor characteristics of two rounds of QXB: Dacha-Baijiu and Ercha-Baijiu. Analysis via HS-SPME-GC x GC-TOFMS revealed a higher number of volatile organic compounds (VOCs) in Ercha-Baijiu, whereas Dacha-Baijiu exhibited elevated concentrations of alcohols and esters. Orthogonal partial least squares discrimination analyses indicated significant flavor differences between the two rounds. Based on odor activity value (OAV >1) assessment, 51 VOCs were identified as key aroma contributors, with beta-damascenone, isovaleraldehyde, ethyl caprylate, and ethyl hexanoate being particularly prominent. Furthermore, 37 volatile compounds were accurately identified using GC-IMS, effectively constructing a fingerprint of the flavor differences between two rounds of QXB. Sensory analysis revealed significant distinctions in both aroma and taste. Dacha-Baijiu exhibited more intense aroma of sweet, floral, and grain, as well as taste of sour and fresh, while Ercha-Baijiu was marked by strong acid, alcoholic, and fruit aroma, as well as sweet, bitter and salty taste. This study elucidates the flavor characteristics of two rounds of QXB, which providing valuable insights for the processing technology and flavor quality control of QXB.