Regulation of the quality, flavour, and microbial community of industrially fermented split red sour soup by Lentilactobacillus buchneri and Pediococcus ethanolidurans.

In order to study the changes in physicochemical properties, microbial diversity, and flavour substances during the industrial fermentation of split red sour soup (RSS) inoculated with lactic acid bacteria (LAB), two groups of samples from natural and inoculated fermentation were analyzed. The physicochemical properties in inoculated fermentation group were better than those of natural fermentation group. Compared to natural fermentation, inoculated fermentation led to rapid acidification, and the increased contents of key volatile compounds (isoamyl acetate, ethyl acetate, phenylethanol, acetic acid, etc.) in sour soup. The dominant bacterial genera in the inoculation group included Lentilactobacillus, Pediococcus, Lactobacillus and Lactiplantibacillus. The dominant bacterial genera in the natural fermentation group were Pediococcus, Lentilactobacillus, Levilactobacillus, and Weissella. The dominant fungal genera in the inoculated fermentation samples of tomato sour soup were Pichia and Hanseniaspora. The dominant genera in the remaining sour soup samples were Kazachstania. Spearman correlation analysis showed that Lentilactobacillus, Levilactobacillus, and other bacterial genera were positively correlated with phenylethanol, isoamyl acetate, and terpenoids in tomato sour soup, whereas Kazachstania, Pichia, Hanseniaspora, Candida, and other fungal spp. were positively correlated with alcohols 2-undecanol, cis-3-hexenyl acetate, etc. In chilli sour soup, most of the bacterial genera were negatively correlated with volatile flavour compounds. Acetic acid was positively correlated with Hanseniaspora and negatively correlated with Candida. This study revealed the effects of LAB fermentation on the flavour quality and microbial community of split RSS and laid the basis for the industrial production of split RSS.