Abstract: The rheological and gel properties of low acyl gellan (LA) and pectin mixtures were studied using a rheometer and a texture analyzer. The effect of different ions (potassium and calcium), different ion concentrations (0, 2, 4, 6, 8, 10, 20, 40 mmol/L) and different LA-to-pectin ratios (100:0, 75:25, 50:50 and 25:75) on mixed gels was investigated. The results showed that calcium ion had a greater effect on failure stress than potassium ion. Failure stress increased with increasing calcium or potassium ion up to the critical level, and then it decreased with further increase in ion concentration. Failure stress of mixed gels increased with decreasing proportion of gellan gum. The strongest interaction occurred when the ratio of LA to pectin was 75 to 25. The viscosity of mixtures decreased with increasing shearing rate. At a content shearing rate, the viscosity was enhanced with increasing LA ratio. Ion type and concentration had identical effects on the viscosity and texture of LA-pectin mixtures. The viscosity was decreased with increasing temperature. For each investigated temperature, the maximum viscosity was observed at a ratio of 75:25. The dynamic rheological results revealed that the storage modulus of mixed gels was greater than the loss modulus, and both of them rose with the increase in LA ratio, indicating that the viscosity and elasticity of mixed systems increased with increasing LA ratio.

Key words: low acyl gellan, pectin, textural properties, rheological properties