Characteristic fingerprints and volatile flavor compound variations in Liuyang Douchi during fermentation via HS-GC-IMS and HS-SPME-GC-MS. (1st November 2021) - Chen, Yi
Graphical abstract: Highlights: 115 kinds of VOCs were identified and most of them were accumulated during the pile fermentation. Most of alcohols and acids decreased while esters and pyrazines increased during fermentation. Hexanol, hexanal and 2-pentylfuran might be responsible for the odors of unfermented black beans. Esters and pyrazine (e.g. ethyl acetate) contributed to the aroma of matured Douchi . Abstract: The present study investigates volatile organic compound (VOC) compositional changes in Liuyang Douchi during fermentation via a HS-GC-IMS and HS-SPME-GC-MS combination approach. A total of 115 VOCs were identified from Douchi, most of which were accumulated during pile fermentation. Notably, most alcohols and acids decreased with fermentation, while esters, ketones, pyrazines, and phenols accumulated during pile fermentation. Depending on the VOCs identified by GC-IMS/MS, the different fermentation stages of Douchi could be facilely distinguished. Of these, 49 VOCs were regarded as the marker VOCs of Douchi in different fermentation stage: hexanol, hexanal, and propanoic acid was the marker VOCs of the black beans before fermentation and contributing beany and grassy odors; 1-octen-3-ol and 3-octanone supplying a mushroom aroma to the Douchi fermented for 3–9 days; and esters and pyrazine, especially ethyl acetate and 2, 6-dimethylpyrazine, contributing the cocoa, fruity, and nutty aromas of matured Douchi .