Nanomaterial-reinforced biodegradable guar gum/gelatin composite films for shelf-life extension of perishable fruits.

Perishable fruits have a short shelf life due to their susceptibility to quality deterioration after harvest. Implementing appropriate preservation measures is an effective strategy to maintain fruit quality and enhance market value. However, traditional polyethylene films not only offer limited functionality but also contribute significantly to white pollution. Consequently, the development of multifunctional bioactive composite films has attracted increasing attention. This study developed a guar gum-gelatin composite film reinforced with cinnamaldehyde-modified ZnO nanoparticles (Cin-m-ZnO NPs) prepared by the solution casting method. Structural characterization revealed that the incorporation of Cin-m-ZnO NPs into the guar gum-gelatin matrix to form composite films effectively improved their barrier properties, mechanical strength, and antibacterial activity. Specifically, the composite film containing 7% (w/w, based on the combined weight of guar gum and gelatin) Cin-m-ZnO (7% Cin-m-Z-GG-G) exhibited inhibition rates of 92.95% against Escherichia coli and 66.18% against Staphylococcus aureus. Soil degradation tests demonstrated that the novel composite film was almost completely biodegradable within three weeks. In fruit preservation applications, the 7% Cin-m-Z-GG-G film not only effectively reduced the decay index, weight loss, and softening of mulberries and strawberries but also maintained their quality, thereby extending the shelf life of these two fruits by six and four days, respectively. Consequently, this cinnamaldehyde-modified ZnO nanoparticle-reinforced composite film emerges as a functional and eco-friendly material, representing a viable biodegradable alternative for sustainable perishable fruit packaging.