Pullulan/zein nanofiber film with synergistic antibacterial effects for strawberry preservation

This study fabricated a pullulan/zein-based (PZ/CT) edible nanofiber film co-loaded with cornmint oil (CO) and thymol (THY) for strawberry preservation. The synergistic antibacterial activity of CO and THY, the electrospinning encapsulation, as well as the physicochemical, functional, and preservation properties of the nanofiber films were characterized. The PZ/CT nanofibers exhibited uniform morphology with an average diameter of 143 nm. The film presented a water contact angle of 82.8°, a water vapor permeability of 0.83 × 10^-10 g·m^-1·s^-1·Pa^-1, a tensile strength of 1.28 MPa, and an elongation at break of 36.5%. It showed UV-shielding capacity and achieved a DPPH radical scavenging rate of 98.2% within 0.5 h. At 25 mg/mL, the film showed inhibition rates of 99.8% against Escherichia coli ATCC 25922, 99.7% against Staphylococcus aureus ATCC 6538, and 100% against Listeria monocytogenes ATCC 19119. Under ambient storage conditions (25 ± 2 °C), PZ/CT packaging extended the shelf life of strawberries to 10 days by retarding microbial growth, weight loss, and quality deterioration. These results indicate that the electrospun PZ/CT nanofiber film could serve as a promising biodegradable active packaging material for fruit preservation.