Properties of gelatin-zein films prepared by blending method and layer-by-layer self-assembly method

In this study, physicochemical and structural properties of gelatin-zein blending films and bilayer films prepared through blending and layer-by-layer self-assembly method under TGase crosslinking were systematically compared. The ratios of gelatin to zein examined were 2:1, 1:1, and 1:2. Results showed that the tensile strength of both blending films and bilayer films was the highest when the ratio of gelatin to zein was 2:1, which was 4.78 MPa and 9.64 MPa, respectively. With the increase of zein proportion, the elongation at break, water vapor permeability (WVP) and melting temperature of both blending films and bilayer films decreased, while the WVP change of bilayer films was not significant. In addition, there is no significant difference in water solubility (WS) between blending films and bilayer films. The water contact angle of bilayer films at 60 s was significantly higher than that of blending films, indicating the higher hydrophobicity of bilayer films. Fourier transform infrared spectroscopy and XRD results indicated the presence of TGase catalyzed covalent crosslinking and intermolecular interactions between gelatin and zein in both blending films and bilayer films. Results could provide theoretical reference for the preparation of sustainable food packaging films.