Photocatalytic/Antimicrobial Active Film Based on Wheat Gluten/ZnO Nanoparticles.

The purpose of this study was to investigate the photocatalytic/antimicrobial properties of biodegradable film based on wheat gluten/zinc oxide nanocomposites (WG/ZnO) for the active packaging of food products. In this study, central composite design (CCD) was used to study the effect of gluten percent (15, 22.5 and 30%) and ZnO percent (0, 2 and 4%) on the photocatalytic, mechanical and physicochemical properties of WG/ZnO film. Some properties of films, including antimicrobial, antioxidant, FT-IR, SEM, solubility, water absorption, thickness, moisture, colorimetric (L*, a* and b*) and opacity were investigated. Antibacterial and antifungal properties of films based on photocatalytic activity were investigated in three wavelengths of 500, 365 and 254 nm on the Escherichia coli and Aspergillus Niger. The results of the photocatalytic/antimicrobial activity of the films showed that pure gluten film had no effect on bacteria and fungi at three wavelengths, but films containing zinc oxide nanoparticles showed a significant inhibitory effect on bacteria and fungi at 365 and 254 nm. Antibacterial and anti-fungal inhibitory effects were observed at 254 nm stronger than 365 nm (p < 0.05). This result showed that at lower wavelengths the photocatalytic activity was induced to the film. The results of the antioxidant test showed that pure gluten had no antioxidant activity, but antioxidant activity increased with increasing zinc oxide nanoparticles significantly (p < 0.05). The results of the FT-IR analysis showed that new interactions between zinc oxide nanoparticles and gluten polymer of wheat were created. The results showed that when the ZnO particle concentration was low, these particles were distributed uniformly, but high concentration of zinc oxide in the film leaded to agglomeration of these particles. [ABSTRACT FROM AUTHOR]