Evaluation of water vapor permeability properties, mechanical, Thermal and morphological properties of edible films prepared from Big Head fish skin gelatin

Edible films are thin biopolymer based materials. The objective of this work was to determine the water vapor permeability, mechanical, thermal and morphological properties of edible films based on big head crap fish skin gelatin. These films were prepared with 3 g gelatin/100ml of water,0-10% sorbitol and 10% glycerol at natural pH. The samples were conditioned at 75±3% relative humidity and 250C for two days before testing. As expected, elongation at break and water vapor permeability increased, but tensile strength and elastic modulus decreased with increasing of sorbitol content. Fish skin gelatin films with 10% glycerol and 5% sorbitol, had highest glass transition and melting temperature in comparison with those films free from sorbitol. SEM images showed that gelatin films with plasticizer were smooth and uniform in surface with lots of cavities and voids in them. The films plasticized by 10% glycerol had smooth glassy surface. Films plasticized with different concentrations of sorbitol and 10% glycerol showed a dense and compact structure in compared with the control unplasticized samples.