Rheological properties and cloud point of aqueous carboxymethyl cellulose dispersions as modified by high or low methoxyl pectin

The addition of an increased amount of soluble fibre pectin in foods is desired due to its proven positive health benefits to human. The aim of this research was to explore the synergies between the commonly used food additives, carboxymethyl cellulose (CMC) and two types of pectin (high or low methoxyl, HM or LM) using rheological methods. The rheological properties of the reconstituted water solutions of the food additive powder were investigated, at different mass concentrations (0.05%-3.00%) and temperatures (4 °C, 20 °C, 37 °C and 60 °C), reflecting those of food storage and food consumption, using small and large deformation rheological measurements. Dynamic tests showed that CMC alone, HM and LM pectin alone and their combinations exhibit strong viscoelastic behaviour, under the conditions used in this study. For CMC solutions, the Cox-Merz rule was found to be obeyed to a reasonable degree at temperatures lower than the cloud point temperature. However, divergence from the Cox-Metz rule is observed when phase separation takes place. The current rheological methods are feasible to examine the synergy in viscosity and elasticity of mixed gel dispersion, which was determined by the polymer interactions via hydrophobic effects and hydrogen bonds depending on variables such as polymer substitution degree, polymer proportions and applied temperature.