Fractal Dimensions of kappa-Carrageenan Gels during Gelation and Swelling

Abstract

A photon scattering technique for research on the sol-gel and gel-sol transitions in kappa-carrageenan-water systems with various carrageenan contents (CC) was utilized for characterizing the fractal dimensions during gelation and swelling. It was observed that the scattered photon intensity I-sc increased at all temperatures with an increase in the CC when I-sc was monitored against temperature. Additionally the sol-gel transition temperatures were found to be much lower than the gel-sol transition temperatures causing hysteresis of the phase transition loops. I-sc increased with an increase in CC at all test temperatures which is attributed to the formation of a fractal-like carrageenan gel. After drying the gels were used in swelling experiments where the gels were immersed in water at room temperature reswelling to the original structure. It was observed that I-sc from the carrageenan gels increased as the CC was increased. The fractal dimension d during gelation was found to increase as the gelation temperature was increased. On the other hand the d values during swelling decreased as the swelling time was increased.