Development and characterization of sodium alginate/tea tree essential oil nanoemulsion active film containing TiO₂ nanoparticles for banana packaging

To improve the postharvest quality and reduce the anthracnose of bananas, the sodium alginate (SA)/tea tree essential oil nanoemulsion (TEON) based bilayer films incorporated with different contents of TiO₂ nanoparticles were fabricated in this work. The developed TEON presented satisfactory DPPH scavenging activity (65.5 ± 1.8%) and antifungal capability (90.5 ± 5.8%). The microscopy images of the cross-section of the films indicated that the bilayer films with well-cross-linked were developed successfully. Notably, the addition of a certain content of TiO₂ to SA greatly improved the UV blocking and water vapor and oxygen barrier properties of the developed film. However, the barrier property of the film was decreased when the TiO₂ content further increased to 4.0 mg/100 mg of SA. The retention of TEO under visible and UV light in the bilayer film was respectively prolonged to 24 days and 32 h when the addition of TiO₂ content was 2.0 mg/100 mg of SA. Finally, the postharvest quality and anthracnose of banana fruits were significantly improved by SA-TiO₂ + SA-TEON film-forming solution treatments. Results from the present work might open up new insights into the approaches of postharvest quality improvement of bananas.