High strength and water tolerance fish gelatin-xanthan gum acid-induced electrostatic film by melt extrusion method

Gelatin is a biodegradable natural polymer that can be utilized in preparing edible films, and its films tend to have defects in mechanical properties and water tolerance, limiting their application. In this study, we combined the acid-induced electrostatic system to prepare the gelatin extruded film, and the relevant mechanisms were explored. The films' thermal stability, microstructure, mechanical properties, water tolerance, and degradability were also evaluated. Films were prepared by adding different levels of xanthan gum and malic acid to the film substrate. Compared to FG-M-0%, FG-MX-0.5% showed a 120.61% increase in tensile strength, a 9.79 °C and a 16.72 °C increase in melting temperature and glass transition temperature, respectively, the acidified FG-MX group as a whole had a higher water contact angle and lower swelling rate. FTIR and XRD confirmed that acid induction enhanced the electrostatic interactions and hydrogen bonding between gelatin-xanthan gum. The results showed that the melt-extruded gelatin film could also maintain the acid-induced electrostatic effect well, with stronger physical properties and better water tolerance, and were conducive to the efficient preparation of gelatin films with desirable properties and the expansion of their range of applications.