Development, characterization and application of intelligent/active packaging of chitosan/chitin nanofibers films containing eggplant anthocyanins

The aim of this study was to develop intelligent/active packaging by using chitosan/esterified chitin nanofibers (CN) film matrix and anthocyanins from eggplant peel extract (EE) to monitor the freshness of pork. Fourier transform infrared spectroscopy, X-ray diffraction and zeta potential results showed that the CN filled into the film network and precisely bonded to the chitosan via electrostatic interactions and hydrogen bonding. Moreover, the incorporation of EE formed hydrogen bonds with chitosan and CN. Thermogravimetric analysis and scanning electron microscopy showed that the films became more compact and that thermal stability was improved. Hydrogen bonding, electrostatic interaction and nanofilling effects synergistically improved the mechanical and barrier properties (water vapor, oxygen and optical barrier properties) of the films with the addition of CN. When the content of CN was 5 wt%, the tensile strength, elongation at break, the water vapor and oxygen barrier properties of chitosan film were significantly increased by about 1.44, 1.52, 1.23 and 5.21 times (p < 0.05), respectively. When EE was added to the films, the antibacterial and antioxidant capacities of the film were significantly (p < 0.05) improved. All the films containing eggplant anthocyanins were sensitive to pH 3–11 buffer solutions, and the films had good ammonia-sensitivity and acid-sensitivity. Chitosan-CN-EE films effectively indicated the freshness of pork during storage. Hence, these results suggested that the chitosan-CN-EE films are promising candidates for intelligent and active food packaging applications.