Rheology-structure properties of gellan systems: evidence of network formation at low gellan concentrations

The dynamic rheology and confocal laser scanning microscopy (CLSM) of gellan at low concentrations (0.005–0.05 wt%) in the presence of 10 mM CaCl2 were investigated at 25 °C. DSC thermograms showed a conformational transition from coil to rigid helix at approximately 41 °C. Microscopy observations demonstrated that at these low gellan concentrations, the level of counter ions induced formation of a network, the compactness of which depended on gellan concentration. The reinforcement of the network structures by the increase of gellan concentration resulted in more elastic gels well evidenced through the rheology of the systems.