Aqueous extracts (named NAP, NAPS and NAPH, respectively) from Naematelia aurantialba fruiting bodies subjected to three different pretreatments, namely, conventional grinding, steam explosion (SE) and high-pressure homogenization (HPH) were obtained by hot water extraction, and their yields, polysaccharide, uronic acid and protein contents, molecular mass distributions and monosaccharide compositions were compared. A simulated in vitro fermentation model was employed to investigate the effects of these extracts on the intestinal flora using high-throughput 16S rRNA gene sequencing. The results showed that the yields and polysaccharide contents of NAPS (64.15% and 75.87%, respectively) and NAPH (61.64% and 72.56%, respectively) were evidently higher than those of NAP. The molecular mass (m_w) of NAP was 1.731 × 10⁶ g/mol, which was higher than that of NAPH, and NAPS exhibited new characteristic peaks. NAP, NAPS and NAPH were all composed of mannose, xylose, glucose and glucuronic acid, and the monosaccharide composition changed slightly after SE and HPH. All extracts changed the composition of the intestinal flora. Both NAPS and NAP had an advantage in increasing the abundance of Macroomonas, NAPH increased the abundance of Bifidobacterium and Lactobacillus (P < 0.05), and NAP increased the abundance of Butyricicoccus (P < 0.05). The yields of short-chain fatty acids (SCFAs) significantly increased with the addition of each extract. Notably, butyric acid content was higher in the F-NAP group, while acetic acid and propionic acid contents were higher in the F-NAPH and F-NAPS groups. This study provides a reference for the efficient preparation of aqueous extracts from N. aurantialba and its application for regulating the intestinal flora.

Soluble dietary fiber (SDF) from edible mushrooms has good biological activity. In order to develop and utilize SDF from edible mushrooms, the present study determined the SDF contents in different edible mushrooms by sequential enzymatic hydrolysis. SDF-rich mushrooms were selected and evaluated for their in vitro antioxidant activity, nitrite adsorption capacity, in vitro glucose-lowering (glucose adsorption capacity, α-amylase inhibitory and α-glucosidase inhibitory activity) and lipid-lowering (cholesterol esterase, pancreatic lipase, and cholesterol micelle solubility inhibitory activity) activities. Finally, SDF from Lyophyllum decastes, which had the best overall bioactivity among all tested species, was selected for structural characteristic analysis. Monosaccharide analysis showed that SDF from L. decastes consisted of glucose, galactose, mannose and glucuronic acid. Fourier transform infrared (FTIR) spectroscopy showed that the SDF exhibited characteristic absorption peaks of polysaccharides. Scanning electron microscopy (SEM) showed that it possessed an obvious porous structure. The results of this study indicate that the SDF from L. decastes is an excellent ingredient for functional foods with hypoglycemic and hypolipidemic activity.