Citric acid-incorporated fish gelatin/chitosan composite films

Transparent and colorless citric acid-incorporated fish gelatin/chitosan composite films were prepared in this work. The addition of citric acid into film forming formulations slowed down the swelling rate and swelling values of the films, which maintained their integrity and resulted in flexible hydrated films. Furthermore, citric acid acted as plasticizer, increasing the elongation at break of the films. Additionally, films showed good UV barrier properties and the incorporation of citric acid and chitosan reduced the E. coli growth, especially for the films prepared with 20 wt % citric acid, highlighting the potential use of these films as active food packaging. These results were related to the changes observed by Fourier transform infrared (FTIR) analysis, which revealed the different protein structure achieved as a function of citric acid and chitosan contents.