Adhesive based on micellar lupin protein isolate exhibiting oxygen barrier properties

In order to minimize the utilization of non-renewable fossil resources, novel polymer sources for food packaging are being investigated. Micellar Lupin Protein (MLP), produced by dilution precipitation has great potential as functional laminating adhesive due to its high adhesion- and oxygen-barrier properties. Formulations of MLP are used as laminating adhesive between high density-polyethylene foil and paper as well as coating for poly(ethylene terephthalate) foil. The application of glycerol, sorbitol and combinations thereof as plasticizers are being investigated. Adhesive behavior as well as oxygen- and water vapor barrier properties were tested. The addition of both plasticizers enabled the preparation of processable coatings showing coherent and homogeneous morphology with improved adhesive behavior and oxygen barrier. When using sorbitol oxygen permeation coefficients of 0.93 cm³ (STP) 100 µm m⁻² d⁻¹ bar⁻¹ were achieved. The laminates containing only sorbitol provided adhesion properties comparable to standard polyurethane laminates with cohesion failure in 100% of the by T-Peel-Test examined cases.