極性多糖類のゲル化に及ぼす食塩の影響

The effects of salts (KCl, NaCl, CaCl_2, MgCl_2) on the gelation of agar, κ-carrageenan and gellan gum were discussed by measuring values of their rupture property and absorbance. The rupture stresses of 0.8.～2.0% agar gels, 1.8～2.3% κ-carrageenan gels and 1.0～2.0% gellan gum gels increased as the concentration of each polysaccharide increased. The rupture stress of agar gel alone changed on the largest scale and that of gellan gum gel alone on the smallest scale. The rupture stresses of 0.8% agar gel, 1.8% κ-carrageenan gel, and 1.8% gellan gum gel were almost the same. The values of _rupture properties of agar gel did not change by adding sodium chloride. On the other hand, the rupture stress and rupture energy of -κcarrageenan gel and gellan gum gel increased as the concentration of sodium chloride increased, but decreased with further increase of the concentration. The gelation of κ-carrageenan and gellan gum was accelerated by potassium chloride more strongly than sodium chloride. The gelation of κ-carrageenan and gellan gum was promoted at lower concentrations of calcium chloride and magnesium chloride. The absorbance of gellan gum gel with calcium chloride was the highest among the polysaccharides with salt. The above results show that salts effected the polar polysaccharides more strongly than the non-polar polysaccharide. However, the effects of salts on the gelation of polar polysaccharides could not be decided exclusively by the polar strength

ジェランガムのゲル化に及ぼすアルカリ土類金属塩の影響

Rupture stress and dynamic viscoelasticity were observed for cylindrically moulded gellan gum gels as a function of alkaline-earth metal salts (MgCl_2, CaCl_2, SrCl_2 and BaCl_2) and polymer concentration. Rupture stress and dynamic viscoelasticity of gellan gum gels containing alkaline-earth metal salts increased up to a certain salt concentration. In the case of gels containing SrCl_2, these increases were observed up to a certain salt concentration and after the drop of these value, then these increased again. Transparency of gellan gum gels containing higher concentration of salt and gellan gum was significantly lower than that of lower concentration of salt and polymer. Syneresis of gellan gum gels containing MgCl_2, CaCl_2, SrCl_2 and BaCl_2 did not observe the signifcant difference