Effect of cinnamaldehyde–tannic acid-zinc acetate nanoparticles and aldehyde crosslinking on properties of chitosan films and their application for beef preservation

Pure chitosan films are relatively fragile and tend to dissolve when they come into contact with water, which limits their application in food preservation. In this study, cinnamaldehyde-tannic acid-zinc acetate (CTZA) nanoparticles and aldehyde crosslinking were used to enhance the mechanical and water barrier properties of chitosan films. Fourier transform infrared spectroscopy and X-ray diffraction analyses showed that cinnamaldehyde had been successfully grafted on the surfaces of chitosan films. The thermal stability and mechanical property of the chitosan films were greatly improved after these modifications. Compared to non-modified films, the tensile strength of modified films increased by about 1.5- and 8.2-fold under dry and wet conditions, respectively. In addition, the moisture content, swelling degree, water solubility, and water vapor permeability of the modified films were all significantly decreased after the aldehyde modification. Interestingly, the modified film showed no significant changes in dimensions after being immersed in water for 24 h. Moreover, the UV-blocking properties and antioxidant activity of the modified films were significantly enhanced. Finally, the modified films extended the shelf life of packaged beef by 5 d. These findings suggest that the modified chitosan films can be used as active packaging materials for food preservation.