Physicochemical, structural and rheological properties of alkali-extracted polysaccharide from fruiting body of Hericium erinaceus

Abstract

An alkali-extracted polysaccharide (HEAEP-0.5) was prepared from the water insoluble residue of Hericium erinaceus fruiting body. Effects of concentration, temperature, pH and salts on its rheological property were systematically evaluated. Its physicochemical property, structural characteristic and intrinsic viscosity were also determined. Results revealed that HEAEP-0.5 was a β-D-glucan polymer, which contained a →3)-Glcp-(1→ backbone branched with Glc units at O-6 position. HEAEP-0.5 was a high molecular weight (5400 kDa and 290 kDa) polysaccharide showing high viscosity with an intrinsic viscosity value as 1.43 L/g, and revealing a triple helix conformation. It exhibited strong shear-thinning behavior and could form weak gels as concentration increased. Increase in concentration and addition of NaCl or CaCl2 elevated the apparent viscosity and gel strength of HEAEP-0.5 solution, while reverse was the case as temperature increased. The gel formed by this polysaccharide at the concentration of 2.0 g/dL was a thermally irreversible gel and was not highly sensitive to temperature changes (5–45 °C). Its apparent viscosity and gel strength were higher under neutral addition (pH 7.0) than those under alkaline (pH 8.0 & pH 9.0) and acidic additions (pH 5.0 & pH 6.0). This study indicates HEAEP-0.5 is a novel hydrocolloid in food and other industries.