Use of antibacterial effective food packaging of crosslinked polyvinyl alcohol/sodium caseinate/silver nanoparticle composite films

In this study, composite films were produced with the solution casting method from prepared solutions by adding 1%, 3%, 5%, and 7% silver nanoparticles (Ag NPs) to blends 60/40 (w/w) ratio of polyvinyl alcohol and sodium caseinate (NCS). Afterward, the films were crosslinked by dipped in a glutaraldehyde bath. This crosslinking method applied to the films did not cause any adverse effects on the surface views of the films. The occurred aldehyde groups confirmed crosslinking. The thermal stability increased with crosslinking and increasing Ag NPs amount. The 1% Ag NP added film showed the highest tensile strength compared with the crosslinked raw film. The lowest moisture content was observed in 5% and 7% AgNP-added films. The used crosslinking method increased the crosslinking efficiency compared with the crosslinking method in solution, ensuring a decrease in the total soluble matter (TSM) amount of the films. In addition, the TSM value continued to decrease proportionally with the increasing amount of Ag NP compared with the raw crosslinked film. Through the lowest swelling rate, the 3% AgNP-added film exhibited the highest crosslinking density. While the water vapor permeability rate of the crosslinked raw film increased, a proportional decrease was observed by increasing Ag NPs. The 7% Ag NP added film exhibited the best barrier property. All films showed antibacterial activity against Escherichia coli and Staphylococcus aureus. It is suggested that the produced composite films can be used as food packaging with an antibacterial effect.