Integrative metabolomics - GC-IMS approach to assess metabolic and flavour substance shifts during fermentation of Yangjiang douchi.

Douchi is traditional Chinese condiment. In this study, electronic sense, GC-IMS and metabolomics were combined to analyse the changes in flavour profiles and metabolites of Yangjiang douchi at different fermentation stages. The results showed that umami was the primary taste characteristic of douchi. Aldehydes, esters, and ketones representing the predominant flavour compounds. Metabolomic analysis identified 13 compounds as key differential metabolites, which were mainly enriched in the arachidonic acid metabolic pathway in lipid metabolism. The correlation analysis indicated that heptanal, hexanal, phenyl acetaldehyde, benzene acetaldehyde and abhexone may be the key aroma substances during fermentation. The major free fatty acids that may act as key flavour precursors are palmitic acid, oleic acid and linoleic acid. This study provides a scientific basis for the industrial regulation of Yangjiang douchi fermentation.