A novel multilayer film based on sodium alginate/k-carrageenan-gelatin incorporated with ZnO nanoparticles and oregano essential oil for active food packing

Multi-layer active food packing films fabricated with outer layer made of sodium alginate (SA) and inner layer made of k-carrageenan (CAR) and gelatin (GEL) contained with oregano essential oil (OEO) and ZnO nanoparticles (ZnO NPs) were developed through layer-by-layer (LBL) assemble method and characterized in this study. The results of fourier transform infrared (FT-IR) demonstrated OEO, ZnO NPs and SA outer layers were successfully incorporated into the multi-layer film system by hydrogen bonding. ZnO NPs significantly improved the mechanical properties, thermal stability, UV resistance and retention of OEO of the films (P < 0.05). Scanning electron microscope (SEM) images clearly showed SA/CAR-GEL-OEO film and SA/CAR-GEL-OEO-ZnO NPs film had a bilayer structure. Noteworthy, the multi-layer films exhibited higher OEO retention compared to the mono-layer films, and compensated the negative effect of ZnO NPs and OEO on the light transmittance while enhancing the UV resistance of the films. The multi-layer films exhibited stronger antioxidant and antibacterial activity than mono-layer films. To summarize, the multi-layer films loaded with OEO and ZnO NPs enhanced antioxidant and antibacterial activities and displayed great potential as active packaging for food preservation.