Physical Properties, Antioxidant and Antimicrobial Activity of Chitosan Edible Films Containing Essential oils

Herbs and spices, having antimicrobial effect, can be incorporated into edible films to extend product shelf life and to reduce the risk of microbial growth on food. Chitosan edible films have shown great promise for their application in food preservation and also are promising systems to be used as essential oils (EOs) carriers. This study aims to investigate the effect of EOs incorporation on the physical, antioxidant, and antimicrobial activities of chitosan films. Methods: Chitosan active films incorporated with cinnamon, clove, laurel, basil, and lemongrass EOs were investigated for physical parameters of color, thickness, opacity, moisture content, and water solubility in order to study the impact of the incorporation of EOs into the chitosan matrix. The antioxidant property of films was determined based on the method of DPPH to analyze and evaluate the quality of tested films. Furthermore, antibacterial activity was carried by agar diffusion method on food spoilage bacteria of Gram-positive Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Gram-negative Escherichia coli (E.coli), Pseudomonas aeruginosa, and klebsiella pneumonia. Results: In general, all chitosan EOs films presented yellowish coloration, slight thicknesses, good transparency in visible light, and high wettability. Compared to other tested films, chitosan film incorporated with clove EO had the highest total phenolic content of ۰.۳۰۳ mg/g Gallic acid equivalent with the highest antioxidant capacity of ۸۹.۹۳% value. All the films exhibited antibacterial activity against the studied food spoilage bacteria except of the chitosan films incorporated with Basil and Lemongrass EOs showed no inhibitory activity against E.coli. A significant antimicrobial bacterial inhibition zone of (۲۰ mm) was assigned for clove chitosan film against Bacillus cereus and Staphylococcus aureus, Lemongrass chitosan film against Pseudomonas aeruginosa, and klebsiella pneumonia, and Basil chitosan films against Pseudomonas aeruginosa. Conclusion: Chitosan active films incorporated with the studied EOs assigned an effective antioxidant and antimicrobial activity to be used for active food packaging.

Keywords:

Antioxidant activity , Chitosan , Edible , Essential oils , Films