Structure, thermal and rheological properties of different soluble dietary fiber fractions from mushroom Lentinula edodes (Berk.) Pegler residues

Four soluble dietary fiber subfractions were obtained via stepwise ethanol precipitation from Lentinula edodes by-products (LESDF). The molecular weight distributions of these four LESDF subfractions were 6.43 × 107 Da, 6.25 × 106 Da, 1.58 × 105 Da and 2.50 × 104 Da, respectively, and they exhibited different surface morphology properties, particle size distribution, ζ-potential and apparent viscosity. Different structural features of LESDF subfractions were analyzed through monosaccharide composition, FT-IR, periodate oxidation and smith degradations. These characteristics affected their thermal (TGA-DSC) properties and the rheological properties of LESDF-containing doughs. Results indicated that the higher the molecular weight of LESDF products, the greater the loss of dietary fiber weight by degradation. Meanwhile, LESDF-3 exhibited the most rheological benefits and the possible repeating unit were investigated by 1D/2D NMR. It was found that addition of LESDF with medium molecular weight and high branching degree played an important role in improving dough elasticity.