Structural characterization and fermentation properties of a novel coix seed polysaccharide (CSP‐A) with prebiotic potential

BACKGROUND Coix seeds, with high nutritional values and health functions, widely grown in East and Southeast Asia, has been traditionally used as a healthy food and medicinal grain for more than 1000 years in China. This study aimed to characterize the structure of a novel polysaccharide from Coix seed (CSP‐A) and investigate its digestion and fermentation properties by human gut microbiota. RESULTS CSP‐A is a water‐soluble neutral polysaccharide (molecular weight ~ 2498 kDa) containing glucose and mannose with pyran group and α ‐glycosidic bond, and mainly contained α ‐ d ‐Glcp‐(1 → and →6), and α ‐ d ‐Glcp‐(1 →) two monosaccharide residues. The main chain of CSP‐A was composed of α ‐1,6‐ d ‐Glc, and with small amounts of linear α ‐1‐ d ‐Glcp as the side‐chains. After 48 h fermentation, 87.77% of total carbohydrate was utilized by gut microbiota. Total short‐chain fatty acids (SCFAs) in the hydrolysate of CSP‐A reached 58.0 mg/mL, higher than in CSP or control. CONCLUSION A novel polysaccharide CSP‐A was purified from coix seed. Compared to the CSP, the purified polysaccharide CSP‐A showed higher utilization rate and better prebiotic activity. As well as promoting the growth of beneficial bacteria, CSP‐A inhibits the growth of intestinal disorders. Therefore, CSP‐A has potential to developed into prebiotic products.