Utilization in situ of biodegradable films produced with chitosan, and functionalized with ε-poly-l-lysine: an effective approach for super antibacterial application

Abstract

In this study, the chitosan (1% w/v) was hydrated in an aqueous solution of glacial acetic acid (1% w/v) by using a magnetic stirrer and mixed with glycerol (0.75% v/v), as a plasticizer. The four types of chitosan films were fabricated by adding 1.5% cinnamaldehyde and 0.05% ε-poly-l-lysine, and the mechanical, physical and antibacterial properties of the treatments were determined. Mechanical results indicated that the addition of cinnamaldehyde significantly increased the tensile strength and decreased the elongation at break. Moreover, the addition of cinnamaldehyde increased the thickness and decreased water solubility, moisture and water vapor permeability. FT-IR showed the formation of Schiff base and hydrogen bonds between the functional groups of the components, which improved the mechanical and physical properties of the treatments. Changes in the surface of the films were evaluated by SEM images. Further, the antimicrobial activity of the films containing cinnamaldehyde and ε-poly-l-lysine was confirmed against gram-negative bacteria Escherichia coli and Salmonella typhimurium and gram-positive Staphylococcus aureus and Bacillus subtilis. Based on the results, the films containing cinnamaldehyde and ε-poly-l-lysine can be used as the functional packaging for food products.