Preparation and characterization of antioxidant and antimicrobial packaging films based on chitosan and proanthocyanidins.

The antioxidant and antimicrobial food packaging films were prepared by using chitosan (CS) and proanthocyanidins (PA). Effect of PA content (0, 5, 10, 15 and 20 wt% of PA on CS basis) on the physical, antioxidant and antimicrobial properties of CS-based films were determined. The prepared CS-PA films showed a brown color. PA incorporation remarkably increased the thickness, water solubility, water vapor permeability, opacity, tensile strength and thermal stability of CS film; whereas significantly reduced the moisture content, oxygen permeability, UV-vis light transmittance, elongation at break and crystallinity of CS film. Scanning electron microscopy showed PA was evenly distributed in the CS film matrix, making the films more compact. Some spontaneous agglomeration of PA was observed in the films when PA contents exceeded 5 wt%. Infrared spectra indicated the intermolecular interactions between PA and CS were through hydrogen bonds. Notably, CS-PA films exhibited improved antioxidant and antimicrobial activity in comparison with plain CS film. Our results suggested CS-PA films could be applied as active packaging materials in food industry.