Integrated proteomics and metabolomics revealed the influence of ultrasonic cavitation effects on the physicochemical properties and metabolic components during Lactobacillus gasseri JM1 fermentation in soymilk

Lactobacillus-fermented soymilk can improve texture and flavor through microbial metabolism. The application of processing techniques that preserve the nutritional value, quality, and bioactive properties of fermented soymilk without compromising their integrity is of great significance. Ultrasound can promote the decomposition of proteins in soymilk by disrupting their structure, and also has a cell wall-breaking effect on the fermentation strains in soymilk, causing the beneficial components of the bacteria to be released into the soymilk, thereby changing the characteristics and material composition of the fermented soymilk and increasing the content of nutrients and the stability of the soymilk. This study revealed that ultrasonic treatment (150 W, 20 min) significantly improved the texture and stability of Lactobacillus gasseri JM1- fermented soymilk, reduced the viscosity of the fermented soymilk (1918.80 ± 112.33 cP), and increased the water-holding capacity of the soymilk (97.12%). Moreover, ultrasonic treatment (150 W, 20 min) also led to an increase in active aglycone isoflavones such as daidzein (17.32 μg/ml) and genistein (24.48 μg/ml) in the fermented soymilk. Metabolomics and proteomics were used to establish a metabolic network of metabolites, revealing the changes in the main metabolic substances in the fermented soymilk before and after ultrasonic treatment. KEGG analysis exhibited that the carbohydrate metabolism and amino acid metabolism pathways of the metabolites in the ultrasonically treated fermented soymilk were obviously up-regulated. This study provides a theoretical basis for the innovation, flavor extension and quality improvement of fermented soymilk products.