Physical and molecular properties of wheat gluten films cast from heated film-forming solutions

The effect of heating film-forming solutions on physical and molecular properties of cast wheat gluten (WG) films was determined. Glycerol-plasticized films were cast from alkaline (pH 10), heat-treated (55, 75, or 95 degrees C for 10 min) solutions of WG in aqueous ethanol, Protein solubility (PS) of films in water decreased (P<0.05) with increasing temperature. Gel permeation chromatograms showed reduced extractability of protein fractions other than omega-gliadins in WG films. This reduced extractability was due to disulfide (S-S) bond formation. SDS-PAGE patterns of native WG and WG film samples suggested increased cross-linking through covalent S-S bonds in films from solutions heated at 75 or 95 degrees C. Water resistance in potential packaging applications of WG edible films could be modified by adjusting heat-treating temperature.