Effects of microbial community succession on volatile profiles and biogenic amine during sufu fermentation

In this study, we investigated microbial community succession and the metabolite changes during 84 days of sufu ripening (a traditional fermented soybean product). Fifty bacteria and ninety-nine fungi were identified. Cyanobacteria that was found in raw material tofu (72.79%) gradually decreased, and the bacterial communities involved in sufu fermentation were predominantly of genera Acinetobacter, Enterococcus and Streptococcus. For fungi, over the post fermentation stage (7-84 days), the top two genera includes Aspergillus and Monascus, accounting for approximately 95% of the whole genera. Seventy-two volatile flavours and seven biogenic amines were detected. And the results showed that sufu may be harmful mainly due to histamine intoxication. Redundancy analysis between microbiota and biogenic amine revealed that bacteria have a stronger effect on biogenic amine (except for cadaverine) than fungi, and histamine was positively correlated with Kurthia. Spearman's correlation (vertical bar p vertical bar > 0.7) analysis showed significant correlation between microbial profile and dominant flavour compounds, Macrococcus and Streptococcus were positively correlated with 12 flavour compounds. These findings help understand the fermentation mechanism and provide useful guidelines about the screening of strains that produce desirable flavours for the production of high quality and safe sufu.