A preliminary study on preparation, characterization, and prebiotic activity of a polysaccharide from the edible mushroom Ramaria flava

Polysaccharides derived from edible mushrooms were sources of new prebiotic compounds. Limited studies of their prebiotic effects, as well as the presence of residual dark colors, impede their use as prebiotics in the food industry. To boost the prebiotic value of polysaccharides from the edible mushroom Ramaria flava, a decolorization method, and the physicochemical characterization and prebiotic potential of the decolorized polysaccharide (DRFP) were investigated in this study. The reversed micelle system consisting of n-hexanol/isooctane (3:7, v/v) and 200 mM surfactant (CTAB) was an appropriate decolorized method for R. flava crude polysaccharide. That decolorized polysaccharide was 101.68 kDa and contained glucose, galactose, mannose, fucose, xylose, rhamnose, arabinose, and glucuronic acid in a ratio of 40.61:26.97:17.72:7.78:6.31:0.11:0.06:0.44. Furthermore, DRFP exhibited typical shear-thinning behavior and possessed good thermal stability. And 98.76% of DRFP was allowed to transit through the oral cavity and gastrointestinal tract nearly indigestibly in vitro fermentation. It also revealed a prebiotic availability through stimulating Lactobacillus rhamnosus proliferation and inducing enterocoel acidification. When utilized as a carbon source, DRFP significantly improves the production of short-chain fatty acids by L. rhamnosus, particularly acetic, propionic, isobutyric, and hexanoic acids. Therefore, this work suggests the further application of R. flava polysaccharides as emerging prebiotics, which may be used as an ingredient in functional food and nutraceutical products. Practical applications Prebiotics could regulate gut microbial community and are closely associated with host health. This work reported that a decolorized polysaccharide (DRFP) prepared from the edible mushroom Ramaria flava was indigestible and could improve Lactobacillus rhamnosus proliferation and short-chain fatty acid production, which could provide useful information for the application of DRFP as a prebiotic additive in the food industry.