The quality characteristics and microbial communities of three components in traditional split-fermented red sour soup.

Red sour soup is a Guizhou specialty condiment made by the natural fermentation of tomatoes and chili. In this study, three components (tomato acid, chili acid, and tomato and chili mixed acid) of split-fermented red sour soup were explored to compare the quality characteristics and microbial communities in the middle and late fermentation stages. The titratable acidity of mixed acids was lower than that of tomato acid and chili acid in the middle stage, but it was significantly increased in the late stage. The cell viability of lactic acid bacteria was mostly higher than that of yeasts during the whole fermentation. Also significantly increased in the late stage of fermentation were sensory scores and the signal intensity of sour substances. However, the signal intensity of both bitter and salty substances decreased, and the total amount of free amino acids was reduced. In addition, the antioxidant capacity of the samples and the dominant microorganisms were different between the two fermentation stages, and were the key common genus of the different components of split-fermented red sour soup. It is anticipated that this study would provide us an insight into the quality characteristics and microbial communities of split-fermented red sour soup.