Antimicrobial effect and physicochemical properties of bioactive trilayer polycaprolactone/methylcellulose-based films on the growth of foodborne pathogens and total microbiota in fresh broccoli

Abstract : Bioactive trilayer films were prepared using methylcellulose (MC) and polycaprolactone (PCL). Two antimicrobial formulations named as A (organic acids, extract of rosmarinic acid and Asian essential oil (EO) mixture) and B (organic acids, extract of rosmarinic acid and Italian EO mixture) were added in MC films during casting and the trilayer composite films (PCL/MC/PCL) were fabricated using compression molding. These films were inserted into packages containing broccoli and the packages were kept at 4 °C during 12 days storage to determine the antimicrobial capacity of the films and the physico-chemical properties of the films. Bioactive films showed a significant reduction of Escherichia coli in broccoli from Day 4 and a total inhibition at Day 12. Similarly, these films showed a significant reduction of Salmonella typhimurium from Day 2 and a total inhibition at Day 7. Moreover, the films controlled the growth of total aerobic microbiota (TAM) in broccoli up to 10 days. Encapsulation of antimicrobial compounds in films allowed decrease of barrier properties of films. Tensile strength of films was not affected by the presence of formulation B. These results demonstrated the potential application of trilayer antimicrobial on controlling food pathogens and total flora in pre-cut vegetables.