Interfacial Properties of the Aqueous Phases of Wheat Flour Doughs

Abstract

Aqueous phases were isolated from wheat flour doughs by ultracentrifugation, using a selection of wheats differing in bread-making quality. The interfacial properties of the aqueous phases of doughs were measured using surface tensiometry and surface rheological measurements. It was found that the material in the aqueous fraction from the cultivar Brock produced the greatest reduction in the surface tension of water and those from the CWRS class of wheat produced the least. Avalon and Mercia cultivars produced intermediate values. The elastic modulus, Gδ, of the adsorbed surface films was highest for CWRS and least for Brock. Avalon and Mercia again produced intermediate values. Lipid and protein measurements of the aqueous phases of doughs and the parent flours showed CWRS flour to contain the highest level of lipid material, whereas its aqueous phase contained the least of the flours studied. Brock flour, which was found to contain the lowest amount of lipid material, had the highest level of lipid in its aqueous phase. Avalon and Mercia were found to contain intermediate values in the flour and their aqueous phases. The influence of endogenous surface-active materials of flour on the interfacial properties of the air-aqueous interface in doughs are discussed.