Exploring the flavor characteristics and key flavor-related metabolic pathways in sour congee of different foxtail millet varieties

Abstract

Sour congee is a traditional non-alcoholic fermented grain food in China; however, the flavor diversity in sour congee of different foxtail millet varieties and key flavor-related metabolic pathways have yet to be thoroughly evaluated. This study analyzed the physicochemical properties, taste components, and aroma compounds of six millet varieties used in sour congee production. Results showed that flavor differences arose from compound concentrations rather than types. Succinic and citric acids emerged as primary taste-active compounds (TAV >1), while 15 volatiles contributed aromas (OAV >1), mainly fruity, green, floral, and fatty notes. The aroma of glutinous varieties and japonica varieties can be visually distinguished by the odor ring charts. Further chemometric analysis revealed six signature aroma compounds that distinguish the different varieties of sour congee (OAV >1 and VIP >1), including phenylacetaldehyde, (E)-2-octen-1-ol, 1-octanol, hexanoic acid, ethyl butyrate, and 3-octanone. The reconstructed key flavor-related metabolic pathways elucidated that these key flavor compounds are primarily generated from pyruvate, fatty acids, and phenylalanine metabolism. In summary, this study highlighted flavor characteristic variations and potential mechanisms underlying flavor substance formation. It was found that JM-fermented congee was conducive to attaining a desirable balance of flavor and antioxidant benefits.