Gelatin Films from Carp Skin Crosslinked by Gallic Acid and Incorporated with Chitosan/Tuna Lipid Fractions

Gelatin was extracted from carp skin and reticulated with gallic acid; afterward, gelatin samples were crosslinked with addition of chitosan produced from shrimp waste and, bleached oil and free fatty acids (FFA) extracted from tuna heads. Carp gelatin showed good yield (20.4%), hydroxyproline content of 13.8% and high gel strength (245 g). Chitosan presented 85%DD and MW of 159 kDa, and the tuna oil had 68.2% of unsaturated fatty acids, being around 29% of EPA and DHA. Films showed thickness, color, and transparencies characteristic of fish gelatins. Films crosslinked with gallic acid, incorporated with chitosan and the tuna lipid fractions showed better mechanical and permeation properties that the other films. FT-IR analysis showed that crosslinking let to an amides II and III decrease, a typical attribute in films with low water vapor permeability. All films presented higher melting temperatures than the pure gelatin film, indicating less thermal degradation and better quality. The results expressed that the incorporations of chitosan, bleached oil and FFA improved the properties of crosslinked gelatin films from carp skin. As all materials used in work are byproducts from fishery industry, this fact could collaborate to reduce the environmental impacts caused by their inadequate discards in nature.