Cost-efficient bio-based food packaging films from the dragon fruit peel and pomegranate peel 

Abstract

In this study, two fruit processing coproducts, pomegranate peel and dragon fruit peel, were mixed to fabricate a composite film that can be used in food packaging. Therefore, the purpose of this study was to prepare and evaluate a dragon fruit peel polysaccharide film incorporating pomegranate peel polyphenols. The films were evaluated for their morphology, mechanical properties, crystallinity, solubility, UV resistance, oxidation resistance, and bacteriostatic properties. Different concentrations (0, 0.3, 0.5, 0.7%, w/w) of pomegranate peel polyphenols were added to the dragon fruit peel polysaccharide film by casting technology. The results showed that the addition of pomegranate peel polyphenols made the film hydrophobic, decreased the water vapor transmission rate of the film, and reduced the solubility of the film (p<0.05). Furthermore, the UV transmittance decreased with increasing concentration of pomegranate peel polyphenols (p < 0.05). By contrast, the thermal properties were not significantly affected by the concentration of pomegranate peel polyphenols. After the addition of pomegranate peel polyphenols, the surface of the film became rougher while the cross-section became smoother. X-ray diffraction (XRD) analysis and Fourier transform infrared (FTIR) spectroscopy showed that the crystalline nature and functional groups of the film did not change significantly. The compatibility of the film-forming substances was good, and the obtained films also exhibited good mechanical properties. Importantly, the addition of pomegranate peel polyphenols endowed the dragon fruit peel polysaccharide film with excellent antibacterial properties, while also significantly improves the antioxidant activity and UV-resistance of the film. The dragon fruit peel polysaccharide film with 0.7% (w/w) pomegranate peel polyphenols showed the best overall performance. This alternative material is a potential substitute for petrochemical packaging, alleviating serious environmental pollution problems.