Improving functional properties of chitosan films as active food packaging by incorporating with propolis

Chitosan films containing 0, 2.5, 5, 10 and 20% w/w propolis extract (PE), high in polyphenols, were developed. The films’ tensile strength, elongation at break, total phenolic content and antioxidant activity increased, while water vapor permeability and oxygen permeability decreased with increasing propolis concentration. Increasing PE concentration resulted in deeper orange color films, as compared to light yellow control films. The ability of the films to inhibit Staphylococcus aureus, Salmonella Enteritidis, Escherichia coli and Pseudomonas aeruginosa was determined using agar diffusion technique. Chitosan films containing PE could inhibit all tested bacteria on contact surface underneath the film discs. Changes in the Fourier Transform Infrared spectra of the films were observed when PE was incorporated, suggesting some interactions occurred between chitosan and propolis polyphenols. The characterization of mechanical properties, oxygen and moisture barrier, and antioxidant and antimicrobial activities revealed the benefits of adding PE into chitosan films and the potential of using the developed film as active food packaging.