Antibacterial konjac glucomannan-based films incorporated with ZnO/Ag/polydopamine-montmorillonite for food packaging application

In this study, silver nanoparticles (Ag NPs) and zinc oxide nanoparticles (ZnO NPs) were co -loaded onto polydopamine-modified montmorillonite (PDA Mt) and incorporated into a konjac glucomannan (KGM) matrix to fabricate biodegradable active food packaging films. The physicochemical properties of the KGM/ZnO/Ag/PDA-Mt films were systematically characterized using XRD, FTIR, TG, XPS, FE-SEM, and EDS mapping. The results showed that the ZnO/Ag/PDA-Mt nanofillers were successfully introduced and well-dispersed in the KGM matrix. XPS analysis further confirmed the presence and chemical states of C, O, Zn, Si, Al, and Ag in the composite film. The composite films exhibited improved mechanical properties, with the 4% KGM/ZnO/Ag/PDA-Mt film showing the highest tensile strength of 18.9 MPa, which was 86.8% higher than that of pure KGM film. The films also displayed strong antibacterial activity, with bactericidal rates of ≥98.04% against S. aureus and ≥ 98.16% against E. coli . In addition, the migration amounts of Ag and Zn in different food simulants were below the corresponding specific migration limits or reference safety limits. In blueberry preservation tests, the 4% KGM/ZnO/Ag/PDA-Mt film effectively delayed fruit deterioration by reducing the weight loss rate to 13% compared with 23% for the control, maintaining fruit firmness at 1.95 N, and preserving total soluble solids at 14°Bx after 10 days of storage. These results indicate that the developed KGM/ZnO/Ag/PDA-Mt composite film has promising potential as a biodegradable active packaging material for blueberry preservation.