Gellan gum fluid gels: influence of the nature and concentration of gel-promoting ions on rheological properties

Abstract

Low-acyl gellan gum fluid gels were obtained using two different gel-promoting cations under the same processing conditions, and their rheological properties were investigated. For that reason, stress and frequency sweep measurements and flow curve tests were carried out. Small amplitude oscillatory shear assays demonstrated that these materials exhibit weak gel behavior despite the shape of their mechanical spectra being similar to those obtained from strong gels. However, the existence of a weak gel structure was confirmed by the fact that the difference between the elastic and viscous components was of only one order of magnitude. In addition, a reduction in the storage and lost modules and the viscosity as a function of the applied shear was observed with increasing cation concentration. Finally, in order to produce fluid gels, a higher concentration of the monovalent cation was required than when divalent cations were employed in the low-acyl gellan gum fluid gel formulation.