Antimicrobial Activity of Two Polysaccharide Edible FilmsIncorporated with Essential Oils against Three PathogenicBacteria

Background: Nowadays, packaging research is receiving considerable attention because of the development of eco-friendly materials made from natural polymers such as chitosan (CH) and hydroxypropyl methylcellulose (HPMC). Essential oils are effective antimicrobials on important some pathogenic bacteria and can be added packaging materials due to absorb various surfaces. Objective: The main purposed of this study was to prepared antimicrobial films by incorporating different concentrations of marjoram, clove and cinnamon essential oils, into chitosan and hydroxypropyl methylcellulose films against foodborne pathogens. Methodology: Chitosan (1% w/w) was dispersed in an aqueous solution of glacial acetic acid (0.5% w/w) at 25EC. Following overnight agitation, essential oils were added to the chitosan solution. Hydroxypropyl methylcellulose 1% weight was dispersed in de-ionized water at 80EC. After the dissolution of the polysaccharide, essential oils were added. Essential oils clove (Syzgium aromaticum), marjoram (Origanum majorana) and cinnamon (Cinnamomum zeylanicum) were extracted by hydro-distillation. The antibacterial effects of essential oils were studied against three important food pathogens, Escherichia coli, Staphylococcus aureus and Listeria monocytogenes by application of agar diffusion method. Also, antimicrobial effectiveness of films were studied by tryptone soy agar with 3% NaCl was used as a model solid food system (TSA-NaCl). Results: The intensity of antimicrobial efficacy was in the following order: Marjoram>clove>cinnamon. The antibacterial effectiveness of the prepared films against E. coli, S. aureus and L. monocytogenes was studied at 10EC during 12 days. The HPMC-EO and CH-EO composite films present a significant antimicrobial activity against the three pathogens considered. In all film matrices, marjoram exhibited the highest antimicrobial activity. A complete inhibition of microbial growth was observed for CH or HPMC-marjoram films for E. coli, HPMC-marjoram for L. monocytogenes and HPMC-clove for S. aureus. Conclusion: The HPMC-EO and CH-EO composite films, containing clove, cinnamon or marjoram, showed a significant antimicrobial activity (bacteriostatic effect) against the three pathogens studied (E. coli, L. monocytogenes and S. aureus). In all film matrices, marjoram exhibited the highest antimicrobial activity.