Enhanced permeability of ZnO/PE films by stretching and its application in Pakchoi preservation

Microbial infection and respiratory metabolism are two primary reasons for the limited shelf life of vegetables. To effectively tackle the issue, this study aimed to enhance the antibacterial activities and gas permeability of PE film by incorporating zinc oxide nanoparticle (ZnO) (2 %, 4 %, 6 %) followed by longitudinal stretch process. The application effects in Pakchoi preservation were further evaluated. The results showed that antibacterial properties and optical barrier of films were improved significantly upon the addition of ZnO. Two different stretch ratios of 2.5 and 5 applied to the films increased the oxygen and water transmission rate. The Zn²⁺ migration concentration of 6 % ZnO/PE film with stretch ratio of 5 was 1.06 mg/L after 14 days. Furthermore, the application results suggested that the 6 % ZnO/PE film with stretch ratio of 5 exhibited the most positive effect on extending shelf life and maintaining the quality of Pakchoi, in terms of rate of weight loss, vitamin C, malondialdehyde, soluble solid content, total viable count. Overall, this study effectively demonstrated that the considerable potential of stretched films incorporated antibacterial agents for application in the preservation of fresh vegetables.