title: Rheological evidence of the gelation behavior of hyaluronan-gellan mixtures.
abstract: It was found that solutions of calcium hyaluronate (CaHA) (0.1 to approximately 0.5 wt%) could form a gel by mixing with solutions of sodium type gellan (0.1 to approximately 0.5 wt%), although neither polymer by itself forms a gel at low concentrations (0.1 to approximately 0.5 wt% in this experiment). The rheological properties of CaHA-gellan mixtures were investigated by dynamic and steady shear measurements. Both storage shear modulus G' and loss shear modulus G'' for CaHA-gellan mixtures increased with increasing time, and tended to an equilibrium value after 1 h. After reaching steady values of G' and G", the frequency dependence of G' and G'' was observed. G' was always larger than G'' in the accessible frequency range from 10(-2) to 10(2) rad/s. The effects of pH and calcium ions were examined. Gel formation of the mixtures was promoted by decreasing pH and adding from 0.01 to 0.1 M calcium ions, but excessive calcium ions weakened the gel.
authors.affiliation: Department of Food and Nutrition, Faculty of Human Life Science, Osaka City University, Sumiyoshi, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Mo
authors.forename: K
authors.initials: K
authors.lastname: Kubota
authors.forename: K
authors.initials: K
authors.lastname: Nishinari
mesh_terms: D002118:Calcium / Q000737:chemistry; D004548:Elasticity; D005782:Gels; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012212:Rheology; D013314:Stress, Mechanical; D014783:Viscosity
chemical_list: D005782:Gels; D011135:Polysaccharides, Bacterial; C048288:gellan gum; D006820:Hyaluronic Acid; D002118:Calcium