Comparative study between cold and hot water extracted polysaccharides from Plantago ovata seed husk by using rheological methods

Cold and hot water extracted polysaccharides (CP and HP) were isolated from Plantago ovata seed husk at 25 and 85 °C, respectively. Their rheological properties were systematically investigated and compared. Different concentrations and temperatures were studied to evaluate the viscoelastic properties of the two fractions. It was found that CP solutions behaved as viscous fluids, while HP solutions preferred to exhibit as gel-like structure. The sol-gel transition process of HP was evaluated and the gel point was determined to be 4.8 mg/mL by Winter-Chambon method in water at 25 °C. The steady flow sweep investigated the viscosity properties of CP solutions and two critical concentrations were found, which locating the transition from the dilute to semi-dilute region, and from the semi-dilute to concentrated region. In addition, the two fractions could form thermo-reversible weak gels, and the gelation temperatures of them increased with the increase of concentration. It is evident that both polysaccharides have significant potential for application in food industry.