Preparation and Characterization of Chitosan-Based Ternary Blend Edible Films with Efficient Antimicrobial Activities for Food Packaging Applications

To improve the mechanical and antibacterial properties of chitosan (CS) films, a ternary blend edible film was prepared by incorporating CS, gelatin (GE), and natural cinnamon essential oil (CEo). Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Fourier transform infrared spectroscopy, and X-ray diffraction were performed to evaluate the films. The mechanical properties, light transmission, thermal stability, hydrophilicity, and antibacterial activity of the films were also determined. The results confirmed all of the films exhibited excellent UV protection with low transparency at 600 nm. Compared with the CS films, the ternary composite film (CSGEo film, containing CS, GE, and CEo) had a higher elongation at break but a lower tensile strength. SEM images revealed that all films had smooth surfaces, although some obvious differences between CS and CSGEo films were observed by AFM. Additionally, the incorporation of GE and CEo to the films enhanced their thermal stability and contact angle, but decreased their crystallinity and wettability. The antimicrobial activity results showed that CSGEo films had excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus, for which the antibacterial rate exceeded 98%. The minimum inhibitory concentrations of the CSGEo solution against E. coli and S. aureus were both 52.06 µg/mL, and the minimal bactericidal concentrations were 104.12 and 52.06 µg/mL, respectively. These results suggest that CSGEo films possess good mechanical and antibacterial properties, and therefore, their application in the food packaging industry is promising. PRACTICAL APPLICATION: The main raw materials of the edible films developed in this study are aquatic by-products, so the films are edible and biodegradable. The addition of gelatin and CEo improved the UV barrier and thermal properties but decreased the crystallinity and hydrophilicity of the films, making them suitable for use as packaging materials. CEo-incorporated films exhibited excellent mechanical properties and antibacterial activity and can, therefore, be used in the food packaging industry.