Carrageenan-gelatin polyelectrolyte complex film with lemon grass essential oil: Synthesis and characterization for active food packaging applications

Abstract

Recent developments on packaging innovations have shown growing interest in active packaging films designed to enhance shelf-life and maintain food quality while ensuring biodegradability to address the emerging problem of overproduction and consumption of single-use plastics globally. In this study, active films based on carrageenan-gelatin (CRG-GEL) polyelectrolyte complex (PEC) with the incorporation of lemon grass essential oil (LGEO) through emulsification were synthesized and evaluated. Generally, the addition of LGEO resulted in an improved film thickness, moisture content, water solubility, and hydrophobicity, which, however, decreased the soil biodegradation rate. A decreased tensile strength and increased elongation at break characterize the mechanical properties of the films, which may be caused by the partial replacement of the strong interaction between the polymers with the weaker polymer-oil interaction, as confirmed by the digital micrographs showing discontinuity and heterogeneity in the film surface layers. Moreover, FTIR analysis revealed a narrowing of the spectral bands in the -OH functional group region upon the direct addition of LGEO and through emulsions with increasing concentrations. However, structural changes were not observed in the films upon the LGEO loading at increasing concentration. Meanwhile, the antifungal effect of the sample films was also determined based on the fungal growth proliferation on white bread samples packaged with the sample films of varied treatments and a control group. Overall, the CRG-GEL-PEC films have retarded the fungal growth on the bread surface, and films with higher LGEO concentrations have inhibited mold formation within the 14- day experimentation period.