Gelation of Iota/Kappa Carrageenan Mixtures

The rheological and thermal properties of kappa carrageenan (KC) and iota carrageenan (IC) solutions and their mixtures were studied using dynamic rheology and differential scanning calorimetry (DSC). Two-step gelation was observed for all KCl concentrations studied (0-70 mM), as seen from two steps of storage modulus (G’) increase and two DSC peaks both on cooling and heating. Ion and water migration between KC and IC solutions was studied by forcing a macroscopic separation across a dialysis membrane. No redistribution of water or ions was found after curing gels for 24hrs, unless the temperature was far below the gelation temperature of KC. This result suggests that gelation of both polysaccharides is not sufficient to cause ion and water migration between KC and IC rich phases (in case phase-separation takes place).