Fabrication of natural polymer-based films for food preservation and packaging application: characteristic assessment of ultra-low graphene content

Embracing bio-based materials for food packaging as a sustainable alternative to conventional plastics aims to reduce environmental impact, enhance food preservation, and encourage the use of renewable resources in the packaging industry. The synergy between bio-based chitosan polymer and graphene nanofiller in food packaging preserves the delicate balance of the environment and results in elevated properties that harmonize with modern technological advancements. Herein, nanocomposite films containing chitosan (CS) and graphene nanoplatelet (GNP) with different concentrations (0.1, 0.3, and 0.6% w/w CS) were fabricated by solvent casting technique. The formation of the nanocomposite was confirmed by FT-IR spectroscopy, which revealed that the amine groups of chitosan have interacted with the carboxylic groups of GNPs. XRD results showed significant enhancement in the crystallinity of nanocomposite film with the GNP concentrations. Furthermore, adding GNP significantly enhanced the mechanical properties (tensile strength and elongation at break) of the fabricated films. The 0.6% GNP-containing nanocomposite film showed a significant (p < 0.05) decrease in oxygen permeability and water vapor transmission rate by ~ 73% and ~ 60%, respectively. The film with 0.6% GNP concentration exhibited excellent antibacterial behavior against Escherichia coli (Gram-negative) bacteria compared to Cellulosimicrobium aquatile (Gram-positive) bacteria. Additionally, the radical scavenging activity, as measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, significantly increased (p < 0.05) with the concentrations of GNP. Moreover, the optimized nanocomposite film (0.6% GNP) effectively prolonged the shelf life of high-moisture green chilies with a promising biodegradability rate (12 days), showcasing the potential as sustainable packaging compared to traditional plastics for food preservation.