Evaluation of the antimicrobial effect of chitosan and whey proteins isolate films containing free and nanoliposomal garlic essential oils against Listeria monocytegenes, E.coli O157:H7 and Staphylococcus aureus

Active antimicrobial packaging is an innovative technique that can enhance safety and shelf life of foods. In this study antimicrobial activity of chitosan and whey protein isolate (WPI) films incorporated with free and nano-liposomal garlic essential oil was investigated against Listeria monocytogenes, Escherichia coli O157:H7 and Staphylococcus aureus.
This study was done in 2015 and disk diffusion method was applied to determine antimicrobial effect of films. Films were cut into circular disks with 9 mm diameter and put on the inoculated BHI agar plates with tested microorganisms. Then plates incubated for 24 h at 37oC. The diameter of inhibition zone was measured by digital caliper. The statistical analysis was done by one-way analysis of variance (ANOVA) followed by Tukey's test.
The results of this study revealed pure chitosan and WPI films alone or incorporated with nano-liposomal garlic essential oil did not show any inhibitory effects on tested microorganisms. Incorporation of 2% or higher concentrations of garlic essential oil to the chitosan solution showed the antibacterial activity of films against all tested microorganisms, whereas when the WPI solution incorporated with 3% or higher concentrations of garlic essential oil the antibacterial activity films was seen against all tested microorganisms. Also the results revealed that S. aureus and L. monocytogenes were more sensitive to chitosan and WPI films incorporated with garlic essential oil.
Our results declared that the films incorporated with garlic essential oil have the potential to be used as an active antimicrobial packaging.