Structural, physicochemical, and functional (antioxidant-antimicrobial) properties of 2-O-methyl-β-cyclodextrin inclusion with hexahydro-β-acids in chitosan films

The use of synthetic packaging films causes serious environmental problems due to difficulty in recycling and poor biodegradability. Therefore, the present study aimed to develop natural biopolymer-based packaging films. As natural materials, chitosan (CS)-based films containing various concentrations (0.05 %, 0.1 %, and 0.15 %) of the hexahydro-beta-acid/2-O-methyl-beta-cyclodextrin (HBA/M-beta-CD) inclusion complex were prepared and evaluated for structural, physicochemical, antioxidant, and antimicrobial properties. Results of morphological analysis and Fourier transform infrared spectroscopy (FT-IR) demonstrated good compatibility between CS and the HBA/M-beta-CD complex and indicated that intermolecular hydrogen bonds were probably formed. Moisture content of the films decreased, whereas water solubility, swelling ratio, and water vapor permeability increased after the addition of HBA/M-beta-CD. Optical test showed that addition of the inclusion complex improved the UV light barrier property. The mechanical properties of the film were considerably increased after the incorporation of 0.1 % HBA/M-beta-CD. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity of HBA/M-beta-CD-CS films was ten times higher than that of the control CS film. Furthermore, the incorporation of HBA/M-beta-CD conferred the films with good antimicrobial activity against various foodborne pathogens. In summary, our results indicated that encapsulation with M-beta-CD was an effective way of introducing HBA into CS film. This film can be used as an active packaging material for food preservation.