Investigation of the role of jiaotou in the processing of Jinhua Dajiao steamed bread using metagenomic and metabolomic analyses

Zhejiang, China, has a tradition of wine-fermented foods, including Jinhua Dajiao steamed bread (JDSB). The traditional leavening agent, jiaotou, confers its properties and taste to JDSB. We examined microorganisms in jiaotou, their effects on processing, and the metabolome using metagenomic and metabolomic analyses. Metagenomics of microorganisms in jiaotou revealed a high average diversity, with Rhizopus sp. being the dominant bacteria. The enriched genes were most abundant in genes related to carbohydrate and amino acid metabolism, with a greater number of non-redundant genes for glycoside hydrolases and glycosyl transferases. The enriched genes may have a direct impact on the organoleptic quality of JDSB. Functional enrichment analysis of different metabolites revealed that pathways associated with linoleic acid, ABC transporter, alanine, aspartate, glutamate, and galactose metabolism were enriched during JDSB processing. We identified a strong correlation between metagenomic functional level and metabolomics pathway enrichment analyses.The results contribute to the improvement of JDSB processing.