Tea tree oil-loaded zein-pullulan-sodium alginate composite films for postharvest mango preservation: physicochemical characterization and preservation efficacy.

To develop active packaging materials for postharvest preservation of fresh fruits, a novel zein-pullulan (Pul)-sodium alginate (SA) composite film loaded with Melaleuca alternifolia essential oil (tea tree oil, TTO) was prepared using a tape-casting technique. At a zein solution-to-Pul/SA solution mass ratio of 1:2.5, the film exhibited enhanced tensile strength and elongation at break. The film also exhibited optimal barrier properties, with the water vapor transmission rate and carbon dioxide permeability reduced to 5.97 × 10-8 and 3.6 × 10-6 g·m/m2·h·Pa, respectively. Fourier transform infrared spectroscopy and X-ray diffraction analyses confirmed good compatibility among TTO, zein, Pul, and SA. Furthermore, treatment of mangoes with film-forming emulsion regulated reactive oxygen species metabolism. When the TTO concentration was 1%, the coating further enhanced the scavenging of reactive oxygen species. Overall, the TTO-containing composite film showed strong potential as a functional material for fruit packaging applications.