Antibacterial Activity of Corn Starch Films Incorporated with Zataria multiflora and Bonium persicum Essential Oils

Abstract

Introduction: Nowadays biodegradable packaging such as edible coatings and films, are known as alternatives to plastic compounds and synthetic packaging since they are carriers for food additives (e.g. natural ingredients) and they do not cause any environmental contamination. Antimicrobial bioactive films are a special type of packaging carrying antimicrobial agents that can reduce the risks of food pathogens and consequently, increase the shelf-life of the foodstuff. Materials and Methods: In this study, the antimicrobial effect of biodegradable starch film containing Zataria multiflora and Bunium persicum (concentration range from 1 to 20 mg/ml) essential oils was examined on four species of bacterial pathogens including Staphylococcus aureus, Escherichia coli, Listeria monocytogenes and Pseudomonas aeruginosa using disk diffusion and plate count assay methods. Results: The results of the disk diffusion method showed that the highest antimicrobial effect of Zataria multiflora and Bunium persicum essential oils was related to the concentration of 20 mg/ml, which in this concentration the maximum diameter of the inhibition zone for S. aureus (most sensitive bacteria) was recorded to be 31.3 mm and 22.36 mm respectively. Also, E. coli was determined as the most resistant bacteria with a diameter of the inhibition zone of 26.13 mm and 19 mm for Zataria multiflora and Bunium persicum respectively. The results of plate count assay showed that there was a significant difference in colony counts of L. monocytogenes, S. aureus and P. aeruginosa treated between films containing the lowest concentration of Zataria multiflora essential oil (1 mg/ml) and control samples (P<0.05). Conclusion: In conclusion, the corn starch bioactive films incorporated with the essential oils of Zataria multiflora and Bunium persicum can be used as safe antimicrobial compounds in the food packaging industry.