Cross-linking of fish gelatins to develop sustainable films with enhanced properties

[Display omitted] •Cross-linking reaction with citric acid caused no change in the film color.•Cross-linked films showed a rougher surface and improved UV light resistance.•Cross-linked films showed higher tensile strength and elongation at break.•Environmental assessment showed a positive effect of the end of life in global warming potential. Transparent, homogenous and resistant renewable films were prepared in this work. In contrast to other natural cross-linkers, the addition of citric acid into film forming solutions caused no change in color, highlighting the potential of these cross-linked films for packaging applications, in which film appearance is a key factor for consumer acceptance. Furthermore, modified films showed lower gloss values, indicating the formation of a rougher surface, which would provide more convenient surface properties when printing the film for commercial purposes was intended. In addition, modified films showed improved light barrier properties, which highlight the potential of these films to prevent oxidation caused by light. Finally, the environmental assessment showed that composting as disposal scenario could provide environmental benefits when using these renewable films, although improvements in raw material extraction and film manufacture are still needed.