Background: Innovative bioactive films incorporated with antimicrobial agents have been recently developed for food preservation. The aim of this study was to evaluate antibacterial activity of Polylactic Acid (PLA) films incorporated with Ziziphora clinopodioides Essential Oil (ZEO) and Ethanolic Propolis Extract (EPE) against some common food-borne pathogens.

Methods: The volatile chemical compounds of ZEO were identified by analytical gas chromatography. Different PLA film groups were prepared using ZEO (1% and 2%) and EPE (1% and 2%), separately and in combination. Disk diffusion method was used in order to evaluate antibacterial activity of experimental groups. The analysis was performed using SPSS 16.0.

Results: The PLA films enriched with the ZEO possess better antibacterial activity compared to the films incorporated with EPE (p<0.05). The descending order antibacterial effects were as follows: Staphylococcus aureus>Listera monocytogenes>Bacillus subtilis>B. cereus>Salmonella entritidis serovar Typhimurium>Escherichia coli O157:H7. The combination of ZEO and EPE showed significantly higher antibacterial effects against all bacteria than those of obtained with each single ZEO or EPE (p<0.05).

Conclusion: The PLA films incorporated with ZEO and EPE had considerable antibacterial activity, indicating potential of these films for application as active packaging in food industry.