Ethylene scavenging film based on low-density polyethylene incorporating pumice and potassium permanganate and its application to preserve avocados

The ethylene scavenging film was prepared to extend the shelf life of fresh fruit and vegetables. This film consisted of low-density polyethylene (LDPE) as matrix, the mixture of pumice and potassium permanganate (KMnO₄) (weight ratio: 10 to 1) (pumice acted as the support of KMnO₄) as active agents, and maleic anhydride grafted polyethylene (PE-g-MA) as compatibilizer. The study revealed that low loadings of active agents (1 wt% and 3 wt%) were evenly distributed in the LDPE matrix and were beneficial to the improvement of the mechanical property, crystallinity, and gas barrier performance against oxygen and water vapor. In addition, the film (thickness: 60 μm) incorporating 3 wt% active agents had an ethylene scavenging capacity of 7.31 μmol/(25 in²) within 12 d at 25 °C. Further, the ethylene scavenging film with 3 wt% active agents preserved avocados well for 20 d at 25 °C, inhibited the ethylene and carbon dioxide (CO₂) concentrations in the packaging headspace, and reduced the flesh firmness loss, while the shelf life of avocados packaged with pure LDPE film was only 10 d.