Fluorescence study on drying of ι-carrageenan gels at different temperatures prepared with various CaCl2 content

Abstract

The influence of temperature and salt content on drying was investigated by using steady-state fluorescence (SSF) technique. Supporting gravimetric and volumetric measurements were also carried out during drying of gels at various temperatures. ι-Carrageenan gels were prepared with various CaCl2 content. Pyranine was introduced as a fluorescence probe during gel preparation. Apparent fluorescence intensity, I, was measured during in situ drying process at each temperature and it was observed that fluorescence intensity values decreased for all gel samples. A simple model consisting of Case II diffusion was used to produce the packing constants, k0, for helixes. It was observed that k0 increased as the drying temperature was increased. On the other hand at each temperature, it was seen that k0 decreased as CaCl2 content was increased. Packing energies for drying processes were obtained from fluorescence, volumetric, and gravimetric measurements separately.