Development and preservative applications of polysaccharide-based bilayer packaging films: Enhanced functional properties through metal-phenolic network-coated zein nanoparticles and biomimetic hydrophobic surfaces

This study develops an innovative bilayer biomimetic hydrophobic film, tailored to provide a sustainable and eco-friendly packaging solution for fresh produce. The outer layer, crafted from chitosan, utilized polydimethylsiloxane templating to mimic the ultra-hydrophobic surface of a lotus leaf, achieving a water contact angle exceeding 130°. The inner layer comprised sodium alginate and zein nanoparticles, enriched with citral and fortified by a metal-phenolic network to facilitate uniform dispersion and controlled release of bioactive agents. The structural design of the film significantly improved mechanical properties, evidenced by a maximum tensile strength of 29.3 ± 3.6 MPa, and enhanced hydrophobicity, reducing water solubility to 28.3 ± 1.5% and substantially decreasing water absorption. The barrier functionality of film was also strengthened, demonstrated by a lowered water vapor transmission rate of 289.3 ± 1.5 g m⁻² 24 h⁻¹, and it supported extended citral release in acidic media up to 70 h. Moreover, the film exhibited robust antioxidant and antibacterial properties. In practical tests, it effectively mitigated weight loss, browning, and hardness degradation in fresh-cut apples and lotus roots, concurrently inhibiting microbial growth and extending shelf life. This study presents an effective strategy for enhancing the hydrophobicity and bioactivity of bio-based films, contributing valuable insights to the field of sustainable food packaging.