Effect of drying method on physicochemical properties and antioxidant activities of Hohenbuehelia serotina polysaccharides

In this study, the polysaccharides (AD-HSP, HD-HSP-1, HD-HSP-2 and FD-HSP) were respectively obtained from Hohenbuehelia serotina through different drying process including air-drying, hot air-drying—50 °C, hot air-drying—75 °C and freeze vacuum-drying. The effects of drying methods on the physicochemical properties and biological activities of the polysaccharides were evaluated on the basis of viscosity analysis, FT-IR spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and antioxidant measurements in vitro, respectively. The results suggested that drying techniques played an important role on the structural characteristics and antioxidant activities of H. serotina polysaccharides. Compared with AD-HSP, HD-HSPs, FD-HSP possessed the greatest intrinsic viscosity with amorphous and tight structure, higher scavenging capacities on ABTS and hydroxyl radicals, more significant reducing power. Therefore, freeze vacuum drying method serves as a good choice for keeping the antioxidant activities of H. serotina polysaccharides.