Antibacterial effect of biodegradable active packaging on the growth of Escherichia coli, Salmonella typhimurium and Listeria monocytogenes in fresh broccoli stored at 4 °C

Abstract

In this study, bioactive films were prepared using two types of film matrices based on i) methylcellulose (MC) and ii) a blend of polycaprolactone/alginate (PCL/ALG). Two antimicrobial formulations named as A [organic acids mixture + rosemary extract + Asian spice essential oil (EO)] and B [organic acids mixture + rosemary extract + Italian spice EO] were added in each type of films during casting. Broccoli florets were inoculated separately with Listeria monocytogenes, Escherichia coli, Salmonella typhimurium to have a final microbial concentration of 5 logs CFU/g sample. Then, antimicrobial films were inserted into packaging containing inoculated broccoli and the package was then sealed under air in standard condition of storage for 12 days at 4 °C. It was found that films containing formulation A had better efficiency against S. typhimurium, with a significant reduction of bacterial concentration until total inhibition after 12 days of storage. In general, bioactive films showed a significant reduction and a good capacity to control the growth of L. monocytogenes and E. coli at short-term storage (4 days). Therefore, these results demonstrated the high antimicrobial potential of both types of films via the diffusion of antimicrobial volatiles on pathogenous bacteria in pre-cut vegetables.