Structural characterization, free radical scavenging activity and α-glucosidase inhibitory activity of insoluble dietary fiber from Pholiota nameko

The insoluble dietary fibers from Pholiota nameko (PN-IDFs) was extracted using the enzyme method with crude fiber content of 87.02 ± 1.68 g/100 g. PN-IDFs had moisture content of 4.96 ± 0.33 g/100 g, ash content of 2.65 ± 0.15 g/100 g, protein content of 3.22 ± 0.51 g/100 g and had strong absorption capacity, including swelling capacity (24.09 ± 1.13 g/g), water-holding capacity (28.22 ± 1.26 g/g) and oil-holding capacity (4.65 ± 0.68 g/g). Scanning electron microscope, Fourier transform infrared spectroscopy and atomic force micrograph suggested that PN-IDFs had the typical structures of multi-ball-aggregate-like shape and polysaccharide functional groups. PN-IDFs exhibited notable cholesterol adsorption both at pH 2.0 and pH 7.0, as well as sodium cholate adsorption. In addition, PN-IDFs displayed strong radical scavenging activities for superoxide anion, hydroxyl radical and DPPH, as well as significant inhibition of α-glucosidase. The results suggested that PN-IDFs could be used as a potentially functional dietary fiber ingredient in food processing.