Biodegradable chitosan-based films decorated with biosynthetic copper oxide nanoparticle for post-harvest tomato preservation.

Postharvest fruit decay caused by pathogens is an important factor leading to product waste and economic losses, and fruit coating is considered an effective strategy to solve this problem due to its simple operation and effectiveness. In this study, nano modified chitosan film (CSC) was created by mixing chitosan (CS) and copper oxide nanoparticles (CuO NPs) synthesized using abandoned Ficus carica fruit. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra indicated the formation of intermolecular interactions between CS and CuO NPs in the composite film. Compared with CS film, the water vapor permeability (WVP), oxygen permeability (OP) and carbon dioxide permeability (CDP) of CSC film were decreased by 71.78 %, 38.03 % and 43.12 %, respectively, while the opacity, tensile strength (TS) and elongation at break (EB) of CSC film were improved by 8.42, 3.42 and 1.89 times, respectively. The in vitro antifungal activity of CSC film against Alternaria alternata was improved by 78.27 %, compared with CS film. Furthermore, CSC coating significantly delayed the development of tomato fruit diseases during storage, reduced respiration rate, ethylene production and weight loss. After 24 d of storage, the decay index and the weight loss rates of fruits in the CS and CSC groups decreased by 25.00 % and 48.54 %, 35.72 % and 54.08 % compared to the control, respectively. CSC coating effectively maintained the contents of ascorbic acid, titratable acid, soluble sugars, total phenols and flavonoids, while increasing copper content in the peel of tomato fruits. Complete degradation of CSC film in soil was extended by 56 d compared to CS film. To sum up, CSC coating can be a potential choice for extending the shelf life of tomato fruits, improving their edible quality and commercialization, and having better environmental friendliness.