Antimicrobial properties of poly (vinyl alcohol) films with zeolitic imidazolate framework (ZIF-8) nanoparticles for food packaging

Antimicrobial packaging films are of interest to the fresh produce industry due to the high number of foodborne illness outbreaks associated with these products. This study evaluated the antimicrobial effectiveness of poly (vinyl alcohol) (PVA) films with embedded zeolitic imidazolate framework (ZIF-8) nanoparticles carrying trans-cinnamaldehyde (TC) against Escherichia coli MG1655 in spinach leaves. PVA films were synthesized using distilled water and mixed at 90 degrees C for 1 h. The synthesized nanoparticles were introduced at various mass ratio concentrations (0%-5% weight of ZIF-8@TC nanoparticles to PVA), namely PVA-Z8-0 (control) through PVA-Z8-5. The PVA and ZIF-8@TC solution was mixed for 24 h until it seemed homogenous, cast, and dried in a ventilated oven at 35 degrees C for 24 h. The release rate of TC from the PVA/ZIF-8@TC into both ethanol and methanol was characterized using HPLC methods. Disk diffusion and growth studies were performed to quantify the films antimicrobial effectiveness. Disk diffusion test showed that antimicrobial activity against E. coli MG1655 increased (p< 0.05) with increased nanoparticles concentration. Growth characteristicswere described by the Baranyimodel with some variations. About 0.26, 0.73, and 1.65 log reductions were achieved with the PVA-Z8-1 to PVA-Z8-3 films, respectively, while total inactivation was achieved with both the PVA-Z84 and PVA-Z8-5 films (p < 0.05). Similarly, the Baranyi model described the inhibitory profiles of the different films. This study contributes to the overall food safety body of knowledge regarding fresh produce and other packaged foods through the development of biopolymeric films with embedded nanoparticles to entrap natural antimicrobials.