Preparation and characterization of konjac glucomannan-based bionanocomposite film for active food packaging

Novel active bionanocomposite films were prepared by incorporating chitosan(CS)/gallic acid (GA) nanoparticles (CGNPs) into a konjac glucomannan (KGM) film. CGNPs with a GA loading efficiency of 78 +/- 2.3% were obtained through ionotropic gelation method, and they presented a spherical morphology with a diameter range of 80-100 nm. The influences of the CGNPs content on the structural, morphological, mechanical, barrier, thermal and antimicrobial properties of KGM/CGNPs films were discussed. The rheological results of film-forming solutions revealed that the CGNPs interacted with KGM through hydrogen bonds in a bionanocomposite matrix, which was coincidence with the fourier transform infrared spectroscopy, X-ray diffraction and thermal analysis results. The microstructure of the films showed that the introduced 5-10% CGNPs appeared to be homogeneously dispersed within the KGM film matrix, thereby reducing the free volume of the composite matrix, and improving the final bionanocomposite films' mechanical, and barrier properties significantly (p < 0.5). In comparison with a pure KGM film, KGM/CGNPs bionanocomposite films showed an excellent antimicrobial activity against food-borne pathogens such as gram-positive (Staphylococcus aureus) and gramnegative (Escherichia coll. 0157:H7) bacteria, because of antimicrobial effectiveness of the CGNPs. Therefore, KGM/CGNPs bionanocomposite films show potential for applications in active food packaging materials.