Properties of gelatin films from giant catfish skin and bovine bone: a comparative study

Edible films were prepared from the gelatin of farmed giant catfish skin (GC) (Pangasianodon gigas), bovine bone gelatin (BB) and their combination. The physical, mechanical, thermal and chemical properties of the resulting films were characterized and compared. The molecular weight distributions of the giant catfish skin gelatin-containing samples had high quantities of alpha-chains, beta-components and high molecular weight cross-links. The bovine bone gelatin-containing samples showed low contents of major bands with high degradation band components. The GC films had higher water activity (0.45) and mechanical properties [tensile strength: TS 41 MPa and elongation at break: EAB 34 (%)] but lower thickness (38 mu m) and water vapor permeability than those of BB films. The lowest light transmission (200-800 nm) and film transparency (3.34) were found in the GC films. However, the color attribute (L, a and b) of BB films was closer to the low-density polyethylene commercial film (Delta E 1.2). The highest value of film and protein solubility (100%) was found in BB film, while the lowest value (41-56%) was found in GC film. The GC films showed the most compact, smooth and continuous surface without porous structures, which corresponds to the greater properties of films.