Large amplitude oscillatory shear behavior and gelation procedure of high and low acyl gellan gum in aqueous solution.

The rheological properties of gellan fluid gels were investigated using large amplitude oscillatory shear (LAOS) technique in both linear and non-linear viscoelastic regimes, with consideration of high acyl (HA)/low acyl (LA) gellan ratio and Ca2+ concentration. The Lissajous curves and Chebyshev coefficients were used to analyze the LAOS data and successfully provided visual and quantitative representation of microstructural differences between HA and LA gellan gum, respectively. Temperature sweep measurements were performed to monitor the gelation procedure of gellan gum solution. The results show that HA gellan gum forms softer but more stable gels than LA gellan gum, especially at high temperature. And a synergistic interaction between HA and LA gellan gum may exist in the presence of abundant Ca2+ ions. The abovementioned study can allow a better understanding of structural characteristic of gellan gum and provide a practical approach to rheological assessment that facilitates the processing and diversified application of mixed gellan gum.