Physical modifications of polysaccharide from Inonotus obliquus and the antioxidant properties

Physical modification of polysaccharides exerted better biological properties because of the change of physicochemical properties. Polysaccharides from Inonotus obliquus (IOPS) were modified by acid, alkali hydrolysis, thermal and ultrasonic treatment in this study. The physicochemical and antioxidant properties of IOPS and its physical modified products were comparatively investigated by chemical methods, gas chromatography, size exclusion chromatography, scanning electron micrograph, circular dichroism spectra, and ferric reducing power assay and lipid peroxidation inhibition assay, respectively. Results showed that physicochemical and antioxidant properties of IOPS were changed after the physical modification of acid, alkali hydrolysis, thermal and ultrasonic treatment. Thermal treated polysaccharide (Th-IOPS) and ultrasonic treated polysaccharide (Ul-IOPS) showed the properties of lower molecular weight distribution, lower intrinsic viscosity, a hyperbranched conformation, and higher antioxidant abilities on ferric-reducing power and lipid peroxidation inhibition activity compared with the native polysaccharide IOPS. Th-IOPS and Ul-IOPS might be explored as a novel potential antioxidant for food industry.