Effect of drying method on mechanical, thermal and water absorption properties of enzymatically crosslinked gelatin hydrogels.

Enzymatically crossliked gelatin hydrogel was submitted to two different drying methods: air drying and freeze drying. The resulting polymeric tridimensional arrangement (compact or porous, respectively) led to different thermal and swelling properties. Significant differences (p < 0.05) on thermal and mechanical characteristics as well as swelling in non-enzymatic gastric and intestinal simulated fluids (37 ºC) were detected. Water absorption data in such media was modelled according to Higuchi, Korsmeyer-Peppas, and Peppas-Sahlin equations. Freeze dried hydrogel showed Fickian diffusion behavior while air dried hydrogels presented poor adjustment to Higuchi model suggesting the importance of the relaxation mechanism at the beginning of swelling process. It was possible to conclude that the same gelatin hydrogel may be suitable to different applications depending on the drying process used.