ABSTRACT
A systematic investigation of the influence of interfacial layer properties on the yield stress and the plateau modulus of different protein foams was done by Lexis et al. who found that foam rheology is tightly related to surface rheological properties of the corresponding protein solutions. Rheology describes the flow and deformation behavior of a material exposed to external mechanical stresses. In principal, this response can be viscous or elastic. Rotational rheometers are widely used for rheological characterization of all kinds of fluids. A manifold of instruments with different specifications is commercially available. In the concentric cylinder measuring system, a shear gap is generated by placing a bob into a cup, both with the same rotational axis. Continuous or steady shear measurements are often used to measure the viscosity in dependence of the shear rate, shear strain, shear stress or time.
