Viscosity measurementsLiquid and foam rheological evaluations were carried out with a Kinexus Pro rheometer (Malvern, Instruments Ltd, UK). A cone-plate geometry with a 4○ angle and a 40 mm diameter was used for all the measurements. For the analysis of viscosity, the liquid solutions were evaluated at shear rates of 1 s—1 to 100 s—1, while the foam preparations were tested at shear rates ranging from 0.01 s—1 to 1 s—1.