Preparation and characterization of polyvinyl alcohol/glutaraldehyde cross-linked chitosan/ε-Polylysine degradable composite film and its antibacterial effect

This work explored the potential feasibility of polyvinyl alcohol (PVA), glutaraldehyde-crosslinked chitosan (GC), and ε-polylysine (ε-PL) antimicrobial biodegradable films within food packaging. PVA is in great demand as a biodegradable material with good extensibility for packaging; however it is highly absorbent and has a sluggish degradation rate. Blending hydrophobically modified chitosan with it improves the poor performance of PVA. In this study, PVA and GC were utilized as film-forming substrates and ε-PL as antimicrobial agents, and different ratios of PVA/GC and PVA/GC/ε-PL film systems were separately probed and synthesized by casting method. It was shown that SEM displayed the most homogeneous and smooth surface as well as the best tensile strength and elongation at break when the ratio of PVA to GC was 75:25. It is noteworthy that the water absorption and water vapor transmission rates of the glutaraldehyde hydrophobically modified chitosan mixed with PVA were much lower than those of the pure PVA film, suggesting that the water resistance of the combination of the two was enhanced. Moreover, incorporating GC and ε-PL made the film appear more cracked, filamentous and blocky after soil burial, especially for pure GC films, where the degradation rate could reach nearly 50%. It is anticipated that the problem of slow degradation of pure PVA plastic can be mitigated by blending it with GC. Crucially, the addition of ε-PL had an inhibitory effect on the growth of Escherichia coli and Staphylococcus aureus. Hence, the prepared PVA/GC/ε-PL composite film has potential applications in food packaging.