Fabrication and characterization of multilayered kafirin/gelatin film with one-way water barrier property

Abstract

A tri-layered film with blend kafirin/gelatin film as core layer, kafirin and gelatin films as skin layers was obtained by layer-by-layer solvent casting method. The surface and cross-section morphology, molecular interactions, mechanical properties, surface wettability and water vapor barrier property of multilayered film were extensively investigated. The cross-section morphology displayed distinguishable individual layers, and heterogenous distribution of spherical aggregations in the intermediate layer was observed. Intermolecular interactions between kafirin and gelatin in the blended film were identified via FTIR. Lamination enhanced the UV protection property while keeping transparency, and the multilayered film made up to the weakness of blend film in tensile strength. Surface wettability measurement demonstrated that kafirin layer possessed lower contact angle than gelatin film surface. Yet, the kafirin layer was more effective in inhibiting moisture penetration than gelatin layer as revealed by the dynamic water absorption analysis and water vapor permeability measurement. Different structural responses of kafirin and gelatin moieties in multilayered films in response to water penetration might explain this phenomenon: while gelatin matrix swelled readily after contact with water, solvent induced aggregation of kafirin moieties led to changes in the compactness of film matrix. Such insights are particularly important in engineering multilayered films with rational designed one-way water barrier property, which is quite useful in fresh fruit and vegetable packaging industry.