GELATION OF CALCIUM ALGINATE - INFLUENCE OF RICE STARCH OR RICE FLOUR ON THE GELATION KINETICS AND ON THE FINAL GEL STRUCTURE

Gelation of calcium alginate in the presence of rice starch or flour was studied. Rate constants, structural diffusion resistance constants, diffusion coefficients, and activation energies of gelation were determined from the gelation time curves. The heterogeneous structural resistance constants were independent of temperature but in the mixtures of calcium alginate with starch depended strongly on the quantity of starch. Activation energy of calcium alginate gelation was 4777 cal/mol. In the presence of rice starch or flour the heterogeneous structural resistance and the activation energy of gelation (9623 cal/mol) increased and the gelation rate decreased. The addition of rice starch or flour to calcium alginate resulted in coarser and more rigid gels with decreased elasticity and resistance to twist and shear. Some of these structural properties of the final gel, for example, the coarseness and rigidity, could be characterized by the kinetic constants of gelation. Because these changes were proportional to the amount of rice starch or flour added to the alginate, it was possible to regulate the viscoelastic properties of calcium alginate gels in this manner.