Antimicrobial N-Halamine incorporated Poly(Vinyl alcohol-co-ethylene) films for reducing cross-contamination of fresh produce

Abstract

Cross-contamination of fresh produce can lead to nationwide foodborne outbreaks. Despite using current sanitation practices, several studies have shown that reusable plastic containers used during the harvest and postharvest processing can be contaminated with pathogenic bacteria. These contaminated surfaces of plastic containers can lead to cross-contamination of fresh produce. The overall objective of this study was to develop a rechargeable antimicrobial plastic film that could be used to reduce cross-contamination of fresh produce in a dynamic postharvest processing environment. An N-halamine precursor incorporated poly(vinyl alcohol-co-ethylene) film was used to charge chlorine via immersion in a dilute bleach to achieve a chlorine-charged plastic film. Cross-contamination was simulated using baby spinach inoculated with 5-log CFU cm−2Listeria innocua to contact a non-contaminated film, which was then contacted by another non-contaminated leaf at different contact times (5–1200 s) and applied forces (1 and 9.8 N). Bacteria on different surfaces were quantified, and quality attributes of leaves such as color, texture, and total phenolic content were measured. The active chlorine content in the charged plastic films reached 445.8 ± 7.2 nmol cm−2 after 1 h chlorination in a 10% diluted bleach solution and remained constant for at least 3 recharging cycles. The self-cleaning activity of the charged plastic films was demonstrated (>2 log reduction of inoculated bacteria) after a 20-min contact and reduced approximately 2 logs of inoculated L. innocua on leaves. The charged plastic films were also effective for reducing cross-contamination of leaves, preventing bacterial transfer from contaminated leaves to non-contaminated leaves without causing a significant quality loss. Thus, the antimicrobial plastic films used in this study can effectively reduce cross-contamination of leafy greens and be potentially used as a liner material or moldable plastic for reusable containers during harvesting and postharvest processing.