Antimicrobial and Physicochemical Properties of Plasma Treated Bio-Coating Polypropylene Films Containing satureja hortensis Essential Oil

Carboxymethyl cellulose-coated polypropylene film containing Satureja hortensis Essential Oil (SEO) was developed based on the casting method as a novel composite bilayer film intended for food packaging. Polypropylene films were initially treated with an atmospheric plasma system to improve adhesion properties. The films were incorporated with 1-4% Satureja hortensis essential oil and were characterized for physical (thickness, moisture content, and water solubility), mechanical (Tensile Strength (TS), and elongation at break), optical, as well as Water Vapor . Permeability (WVP), and microstructure (SEM) properties. The antimicrobial activity of the films against five selected bacteria including S. aureus, B. cereus, E. coli, S. Typhimurium, and P. aeruginosa was also examined with direct contact and vapor phase methods. Results showed that higher SEO incorporation dosage led to significantly lower solubility and permeability of bilayer film (P<0.05). Additionally, by increasing SEO concentration, more opaque and stretchable films with less resistance to breakage were obtained. Films incorporated with 2-4% SEO effectively inhibited all tested microorganisms both in direct contact and vapor phase. Results of the present study suggest that SEO incorporated PP/CMC films as a novel structure of biopolymer coatings on common plastics that can be potentially used as active packaging for food products.