Light Scattering and Viscoelasticity of Aggregating and Gelling κ-Carrageenan

Abstract

We have studied the evolution in time of the shear modulus and the scattered light intensity of aqueous κ-carrageenan solutions at various concentrations and temperatures. Aggregation was induced by cooling solutions containing 0.01 M KCl. The ionic strength of the solutions was fixed by adding 0.1 M NaCl. The time dependence was found to be similar at all concentrations and temperatures investigated. Equilibrium was not attained even after 12 h maturation. The temperature dependence is mainly kinetic and diverges at a temperature close to the temperature of the coil−helix transition of κ-carrageenan. Varying the concentration influences both the aggregation kinetics and the strength of the gels. No critical minimal concentration for gelation is observed.