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Liquid-liquid microextraction (LLME) combined with gas chromatography-mass spectrometry (GC-MS) and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) were used to detect the variations in volatile compounds during the distillation process of strong flavor raw Baijiu. The 3D fingerprint spectrum clearly showed a variation in volatile compounds from different distillation stages, and most alcohol-soluble and low molecular weight compounds showed a downward trend with the extension of distillation time, but water-soluble, high molecular weight and high boiling compounds showed the opposite result. Then, 50 aroma compounds were sniffed and identified by gas chromatography-olfactometry-mass spectrometry (GC-O-MS) and multivariate statistical analysis including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) confirmed four aroma active markers related to classification. Finally, the receiver operating characteristic (ROC) curve was further used to verify that ethyl butanoate and ethyl hexanoate were the most effective difference marker to distinguish the head Baijiu samples and butanoic acid was the most effective difference marker for distinguishing the heart Baijiu samples from the tail Baijiu samples. [Display omitted] • LLME coupled with GC-O-MS was used to analyze the changes of aroma active compounds. • GC-MS and GC-IMS were compared the differences in the detection of compounds. • ROC curve was used to verify the most effective difference markers. [ABSTRACT FROM AUTHOR]

• The feruloyl esterase activity in different layers of Jiupei at different fermentation times were determined and tracked. • The microorganisms with feruloyl esterase activity were screened and identified in Jiupei of sesame-flavor baijiu. • The conditions of enzyme production were optimized by liquid fermentation. Baijiu is a national beverage in China. Some functional compounds have been identified in baijiu, one of which is ferulic acid. One route for in situ ferulic acid synthesis is catalysed by feruloyl esterase from microorganisms using baijiu raw materials as substrates. However, few studies have focused on microorganisms obtained from baijiu that have feruloyl esterase activity. In this work, microorganisms with feruloyl esterase activity were screened in the fermented raw materials of baijiu. Four different microorganisms with feruloyl esterase activity were identified, and one strain, designated J1, showed high feruloyl esterase activity. The strain J1 belonged to the genus Acetobacter and showed the closest relationship with Acetobacter fabarum and Acetobacter lovaniensis. The feruloyl esterase production capacity of J1 was confirmed, and the fermentation conditions were optimised. The optimal enzyme production conditions for the highest feruloyl esterase activity required an initial fermentation pH of 7.0 at 30 °C, an inoculation volume of 10 %, and culturing for 24 h. [ABSTRACT FROM AUTHOR]