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

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Abstract

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.