Incremental effects of fermentation of soybean on its nutrients, flavor profile and laxative regulation in experimental constipated rats.

This study developed a probiotic -fermented soybean powder (EFSP) and analyzed its nutrient profile, volatile components, and laxative efficacy in rats. After 8 days fermentation, polysaccharide contents significantly decreased, while total flavonoid levels initially increased in the first 6 days, and then decreased rapidly. Isoflavone glycosides were reduced, accompanied by an increase in isoflavone aglycones. Additionally, marked changes were observed in the composition and content of short-chain fatty acids, protein-based amino acids, and volatile compounds. Furthermore, EFSP demonstrated superior laxative effects to non-fermented soybean powder (NFSP) in diphenoxylate-induced constipated rats, primarily by modulating the aquaporins, mucin and enteric neuro factor levels in the colonic tissue. Metabolomics indicated that linoleic acid, primary bile acid synthesis, and taurine and sulfinic acid might be involved in constipation regulation. These findings suggested that fermentation enhances the nutritional properties of soybean, contributing to its distinctive nutritional quality.