Abstract
This study aimed to evaluate the effects of tannic acid (TA) and caffeic acid (CA) as cross-linking agents on the physicochemical and mechanical properties of cold-water fish gelatin films. TA and CA (1%, 3%, and 5% of dried gelatin) were incorporated into the fish gelatin film solutions, and film samples were prepared using the solvent casting method. The gelatin film without phenolic acids was considered as the control sample. The results demonstrated that establishing cross-linking bonds between gelatin polymer and phenolic acids improved the film stability, and water solubility decreased from ~ 100 to ~ 40%. The lowest amount of oxygen permeability and the highest darkness were observed in the films containing the highest levels of phenolic acids. The incorporation of TA and CA into gelatin films also increased mechanical strength from ~ 28 to ~ 50 MPa. In conclusion, these results indicated that fish gelatin films cross-linked by two natural cross-linking agents (CA and TA) might be used as edible films and biomaterials, and TA is a more effective phenolic compound than CA.