Investigation on sweaty off-flavors in small mill sesame oil and its formation mechanism via molecular sensory science, preparative gas chromatography, and microbiomics

The distinctive and enjoyable aroma of small mill sesame oil (SMSO) originates from the aqueous extraction process. However, in the sedimentation stage in industrial production, when the external ambient temperature is elevated, unpleasant sweaty off-flavors may be present from an unknown source. Based on the odor screening and verification strategy, 76 volatile flavor compounds were identified in different SMSOs, and 3 key areas had a sweaty odor via gas chromatography olfactometry (GC-O) analysis. The validation experiment utilizing preparative gas chromatography (pre-GC) confirmed the sweaty off-flavors were butyric acid, 2-methylbutyric acid, and isobutyric acid, with odor activity values ranging from 1 to 100. Furthermore, microbiological investigations on sesame residues gathered during the sedimentation process at various temperatures revealed sweaty off-flavors were mostly attributed to the collaborative interaction of Lactobacillus, Yarrowia lipolytica, and butanoate 1-phosphotransferase. This study offers a fundamental theoretical foundation for enhancing the quality control and flavor of SMSO.