Effects of carbohydrate/protein ratio on the microstructure and the barrier and sorption properties of wheat starch–whey protein blend edible films

BACKGROUND: Starch and whey protein isolate and their mixtures were used for making edible films. Moisture sorption isotherms, water vapour permeability, sorption of aroma compounds, microstructure, water contact angle and surface properties were investigated. RESULTS: With increasing protein content, the microstructure changes became more homogeneous. The water vapour permeability increases with both the humidity gradient and the starch content. For all films, the hygroscopicity increases with starch content. Surface properties change according to the starch/whey protein ratio and are mainly related to the polar component of the surface tension. Films composed of 80% starch and 20% whey proteins have more hydrophobic surfaces than the other films due to specific interactions. CONCLUSIONS: The effect of carbohydrate/protein ratio significantly influences the microstructure, the surface wettability and the barrier properties of wheat starch-whey protein blend films. © 2016 Society of Chemical Industry.