Antimicrobial Activity of Chitosan

Abstract

Antimicrobial and physicochem. properties of chitosan films and chitosan films enriched with essential oils (EO) were detd. in vitro and on processed meat. Antimicrobial effects of pure EO of anise, basil, coriander, and oregano, and of chitosan-essential oil films against Listeria monocytogenes and Escherichia coli O157:H7 were detd. by an agar diffusion test. The antibacterial effects of the EO were similar when applied alone or incorporated in the films. The intensity of antimicrobial efficacy was in the following order: oregano > > coriander > basil > anise. The chitosan films and chitosan-oregano EO films were applied on inoculated bologna samples and stored 5 d at 10 DegC. Pure chitosan films reduced L. monocytogenes by 2 logs, whereas the films with 1% and 2% oregano EO decreased the nos. of L. monocytogenes by 3.6 to 4 logs and E. coli by 3 logs. Pure chitosan films were 89 mm thick, whereas addn. of 1% and 2% oregano EO increased thickness to 220 and 318 mm, resp. During application on bologna disks, the films absorbed moisture, resulting in the final thickness of 143, 242, and 333 mm, resp. Addn. of oregano essential oil into the chitosan films decreased water vapor permeability, puncture and tensile strength, but increased elasticity of the films. The films have the potential to be used as active biodegradable films with strong antimicrobial effects.