A Gelatin-Based Film Reinforced by Covalent Interaction with Oxidized Guar Gum Containing Green Tea Extract as an Active Food Packaging System

This study aimed to improve the physicochemical performance of fish gelatin–based films. In this regard, the reinforced gelatin-based films were developed by covalent interaction with oxidized guar gum (OGG) containing green tea extract as an active food packaging system. The reinforced films were prepared by covalent crosslinking between the amino groups of gelatin and the aldehyde groups of OGG using the casting method. Then, the properties and structure of films were studied through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), mechanical properties, water solubility, moisture content (MC), and water vapor permeability (WVP) analyses. After the crosslinking between gelatin and OGG with a ratio of 2:1 (OGG 0.25% w/v): (gelatin 5% w/v), a significant (p < 0.05) decrease was observed in solubility, moisture content, and water vapor permeability of film. The covalent bond formation between OGG and gelatin was also proved as successful by FTIR spectroscopy. The tensile strength of the optimized gelatin-OGG film (78.99 ± 0.4 MPa) was ~ 2-fold higher than that of the gelatin-GG film. Moreover, thermal stability of the optimized film was improved after crosslinking. The optimized film showed higher antioxidant activity due to the presence of green tea extract (0.5 and 1% w/v). The antimicrobial activities were also evaluated against Staphylococcus aureus as the gram-positive bacterium. The obtained results suggested that the optimized film could be considered as a good candidate to be used as an active food packaging system.