Study of the biological fermentation modification of okara dietary fiber on the regulation on gut microbiota and lipid metabolism in hyperlipidemic mice

Okara is produced in large quantities annually in China, but much of it is discarded due to its high content of indigestible dietary fiber (DF), contributing to significant environmental challenges. Recognizing the underexplored medicinal potential of DF, we developed an efficient fermentation method to enhance the bioavailability of okara fiber. In this study, Pediococcus acidilactici IFJ-1, which has strong enzymatic production capabilities and beneficial effects on gastrointestinal flora modulation, was selected to ferment okara. Results showed decreases in viscosity and particle size, optimized surface structure, improved thermal stability and hydration properties, and a significant increase in soluble DF content from 1.85% to 3.91%. To evaluate the physiological effects, hyperlipidemic mouse models were established and subjected to dietary interventions utilizing okara and fermented okara to measure changes in physicochemical parameters, gut microbiota composition, and lipid metabolism. The dietary intervention was effective, particularly in the fermented okara group, showing a 7.3% weight loss, improved blood lipids (triglycerides: ‒39.8%, total cholesterol: ‒12.8%, low-density lipoprotein cholesterol: ‒34.2%, high-density lipoprotein cholesterol: +26.2%), and a 22.2% lower liver index. Gut microbiota analysis revealed that fermented okara positively modulated the microbial community by increasing the abundance of beneficial bacteria (e.g., Bacteroidota) and reducing the abundance of obesity-associated bacteria (e.g., Bacillota). Lipid metabolism profiling further demonstrated that fermented okara downregulated harmful lipids (e.g., (O-acyl)-ω-hydroxy fatty acids, ceramides, and diacylglycerols) while upregulating beneficial phospholipids (e.g., phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, lysophosphatidylinositol and lysophosphatidic acid). This study highlights a novel approach for enhancing DF utilization through fermentation, providing valuable insights into strategies for preventing obesity and metabolic diseases.