Rheological Characteristics of Fucoidan Isolated from Commercially Cultured Cladosiphon okamuranus

Rheological characteristics of fucoidan isolated from commercially cultured Cladosiphon okamuranus (Okinawamozuku) were measured with a rheogoniometer in an aqueous solution. The flow curves of the fucoidan at 25 °C showed shear-thinning behavior below 1.5% (W/V), but plastic behavior at 2.0%, the yield value of which was estimated to be 2.0 Pa. The dynamic viscoelasticity of the fucoidan increased linearly with an increase in concentration >1.0%. The dynamic viscoelasticity decreased gradually with increase in temperature. A little higher dynamic viscosity was observed than storage modulus in fucoidan solutions at various concentrations. The dynamic viscoelasticity of the fucoidan increased with addition of NaCl and CaCl 2 (0.1%). The dynamic viscoelasticity of the fucoidan was stable over a wide pH range. The fucoidan isolated from commercially cultured Cladosiphon okamuranus had unique rheological characteristics in aqueous solution.