Functional properties of wheat gluten/montmorillonite nanocomposite films processed by casting

Wheat gluten/montmorillonite (WG/MMT) nanocomposite films were prepared by casting. Transmission electron microscopy observations showed that MMT nanoparticles were homogeneously distributed within the matrix but not completely exfoliated. Contact angles, water uptake and water vapour sorption measurements showed that the presence of MMT led to a significant reduction of the water sensitivity of WG-based materials. This effect was attributed to a different structuring of protein network in the presence of MMT. Significant changes in the permeability of films towards water vapour and aroma compounds were observed for MMT contents higher than 5 wt%, while O2 and CO2 permeabilities remained unchanged. Finally, a slight improvement in tensile properties was obtained for filler contents higher than 2.5 wt%.