Rheological properties and thickening effect of high molecular weight exopolysaccharide and intracellular polysaccharide from Schizophyllum commune

Abstract

Edible and medicinal fungal polysaccharides with excellent biological activity and high viscosity are potential thickeners for food applications. In this study, the rheological properties of aqueous solutions of exopolysaccharide or fermentation broth polysaccharide (SCFP) and intracellular polysaccharide or mycelial polysaccharide (SCMP) obtained from liquid submerged fermentation of the fungus Schizophyllum commune (S. commune), and their thickening effects on coffee and fruit tea were investigated. The polysaccharide aqueous solutions behaved as pseudoplastic fluids, and their viscosity was concentration-dependent but not significantly affected by temperature (10–70 °C). The critical concentrations (c*) of SCFP and SCMP were 0.275 g/L and 0.356 g/L, respectively. The intensity of the thixotropic properties of the polysaccharide aqueous solutions was positively correlated with polysaccharide concentration. Both polysaccharide solutions exhibited solid-like viscoelastic behavior and formed weak gels, with enhanced gel strength at high concentrations and low temperatures. The viscosity at a shear rate of 50 s−1 (η50) of the 5 g/L SCFP- and SCMP-thickened coffee was 0.07 Pa·s, while that of SCFP- and SCMP-thickened fruit tea was 0.1 Pa·s and 0.08Pa·s, respectively, which were significantly higher than that of polysaccharide aqueous solutions (0.05 Pa·s for SCFP and SCMP). The yield stress values increased with increasing polysaccharide concentration, suggesting a potential role of for these polysaccharides in dysphagia management. Overall, SCFP and SCMP have significant potential for application in the food industry.