Microecological succession and quality enhancement of fermented tomato sour soup by synthetic functional microbiota.

Tomato sour soup, a traditional fermented food with health benefits, often exhibits inconsistent quality during natural fermentation. Three microbial consortia (yeasts, Eurotium, and their combination) were engineered to enhance fermentation. Physicochemical parameters, antioxidant activity, microbial communities, and metabolomic profiles were monitored throughout fermentation. Eurotium inoculation produced the strongest effects, including the highest total acid (21.10 g/kg), total phenolics (75.41 mg/g), and total flavonoids (29.41 mg/g), the lowest nitrite accumulation, and superior DPPH/ABTS radical scavenging activities. Multi-omics integration revealed that Eurotium reshaped microbial succession, activated phenylpropanoid and flavonoid biosynthesis pathways, and drove the biotransformation of flavonoids into more potent antioxidant derivatives, including quercetin and phloretin. These findings demonstrate that Eurotium is a promising microbial strain for improving the quality and antioxidant properties of tomato sour soup.