Dynamic surface tension and surface shear rheology studies of mixed β-lactoglobulin/Tween 20 systems

摘要

The mechanical behaviour of β-lactoglobulin (BLG) and BLG/Tween 20 adsorption layers at the air/water interface has been studied by dynamic surface tension and surface shear rheological measurements. The adsorption properties were measured using different surface tension methods (ring tensiometry, drop volume tensiometry and axisymmetric drop shape analysis). The surface shear rheological measurements were performed with a torsion pendulum set-up which simultaneously provides information about the surface shear viscosity and elasticity. The adsorption layer structure is controlled by the interactions between protein and surfactant molecules. The corresponding dynamic surface tension measurements confirm the peculiarities foun adsorption layer. With increasing surfactant concentration at constant protein concentration the mixed surface film gradually approaches a state identical to a pure surfactant adsorption layer, from which the protein is completely repelled.