Analysis of Microbial Community and Flavor Compounds in low-salt fermented doubanjiang (doubanjiang)

Three sets of doubanjiang samples with salinity lower than the commercially available ones were prepared. The total acid, amino acid nitrogen, bacterial and fungal abundance and community, volatile flavor compounds contents, and the correlation between microbes and flavor compounds were tested and analyzed periodically during fermentation. In the doubanjiang samples with lower salt concentration, the contents of total acid and amino acid nitrogen representing the fermentation process were higher, indicating that the microbes were more active. High-throughput sequencing showed that the types of the microbial communities were slightly affected by salinity. Regardless of the salt concentration, the fungi were mainly Aspergillus and Millerozyma, and the bacteria were mainly Bacillus and Staphylococcus. However, the abundance of each microbe was closely related to the salinity, and the abundance of fungi in 11% salt sample significantly higher than the other two sets. Besides, Millerozyma was greatly abundant in the lowest salt sample, but not detected in the highest salt sample. Due to the decrease of salinity, the conditional pathogens Klebsiella, Cronobacter and Acinetobacter appeared, which need to be paid enough attention and find suitable control methods. Analysis of volatile flavor compounds showed that the contents of various flavor compounds decreased with increasing salinity. Volatile flavor compounds analysis showed that the content of various flavor compounds decreased with increasing salinity, which also reflected better microbial activity in low-salt doubanjiang. Correlation analysis with bacteria showed that Bacillus had a positive effect on flavor, while Staphylococcus and Enterococcus had a negative effect. This study provided a lot of information on the fermentation of low-salt doubanjiang, which helped to further explore the technology of low-salt doubanjiang.