Modelling of Swelling by the Fluorescence Technique in Kappa Carrageenan Gels
Kappa (-kappa) carrageenan gels prepared with various carrageenan concentrations in pure water were completely dried and then swelled in water vapor. Steady state fluorescence measurements were performed using a spectrometer equipped with temperature controller. Pyranine was embedded in kappa-carrageenan gels as a fluorescence probe during gel preparation. The fluorescence intensity I increased exponentially as swelling time is increased for all gel samples. The increase in I was modelled using Li-Tanaka equation from which swelling time constants tau(c) and cooperative diffusion coefficients D-c were determined. It was observed that D-c increased as the swelling temperature was increased. On the other hand at each temperature it was seen that D-c decreased as kappa carrageenan concentration was increased. Activation energies for swelling were obtained and found to be 57.4 58.3 and 62.73kJ mol(-1) for the gels with increasing amount of kappa-carrageenan content.