Extruded transglutaminase-modified gelatin–beeswax composite packaging film

Fish gelatin (FG) is a natural biodegradable biopolymer. However, solution casting, which is commonly used to prepare gelatin films, limits large-scale film production. In this study, melt extrusion (ME) commonly used in traditional plastics was successfully applied to the preparation of gelatin composite films. The non-covalent crosslinking between hydrophobic beeswax (BW) and hydrophilic FG not only reduced the film stickiness during rolling but also decreased the water solubility of the film by 45.17% (p < 0.05). Transglutaminase (TGase) promoted covalent crosslinking between the FG networks, thereby improving the properties of the film. The results of Fourier transform infrared (FTIR) spectroscopy confirmed the crosslinking effect of BW and TGase on the gelatin films, and appropriate crosslinking maintained the forward movement of gelatin in the rotating screw according to a linear mode. The FG–BW–1%TGase film exhibited the lowest water solubility of 36.63% and the highest tensile strength of 6.26 MPa. The co-crosslinking of TGase and BW contributed to the preparation of melt-extruded composite films exhibiting desirable properties and were potential candidates for commercial food packaging.