New insights into adlay seed bran polysaccharides: Effects of enzyme-assisted Aspergillus niger solid-state...

Adlay seed bran, typically discarded or used as animal feed, represents a significant resource waste. This study investigates the structural and physicochemical properties, in vitro digestive behavior, and fecal fermentation profiles of adlay seed bran polysaccharides (ASBPs) prepared using different methods. These methods include hot water extraction, Aspergillus niger solid-state fermentation (SSF), and enzyme-assisted SSF with β-glucosidase, cellulase, and xylanase, referred to as ASBP, ASBP-F, ASBP-GF, ASBP-CF, and ASBP-XF, respectively. Results showed that enzyme-assisted SSF with A. niger improved extraction efficiency and uniformity of ASBPs, increasing total neutral sugars, uronic acids, mannose, and galactose while reducing glucose content, molecular weight, and particle size. ASBP-CF had the best extraction rate, sugar content, lowest molecular weight, finest uniformity, and smallest particle size. In simulated digestion tests, all ASBP variants were stable in stomach and small intestine conditions but degradable by human fecal microbiota, showing varying fermentability levels. ASBPs increased Bacteroidetes populations, inhibited Proteobacteria growth, and enhanced short-chain fatty acid (SCFAs) production, with ASBP-CF showing the highest fermentability and prebiotic efficacy. ASBP-CF was particularly effective in promoting beneficial bacteria like Bacteroides and restraining harmful bacteria such as Escherichia_Shigella, producing more SCFAs during fermentation. These findings suggest that ASBP-CF has potential as a dietary supplement to improve gut health, presenting a high-value utilization strategy for adlay seed bran.