Adsorption of<i>β</i>-Lactoglobulin onto the Surface of Stainless Steel Particles

Abstract

The adsorption of β-Lactoglobulin (β-Lg), one of the main constituents of fouling deposits in milk processing, onto the surface of stainless steel particles was studied under various conditions. The adsorption isotherm of β-Lg at 25°C was of the Langmuir type, and the plateau suggested that the surface was covered by a monolayer of β-Lg. The amount of β-Lg adsorbed steeply increased above 65°C. At 75°C, it increased almost linearly with the protein concentration in the bulk solution. Heating and chemical modification of the SH-group caused a much smaller amount of β-Lg to be adsorbed at 75°C. These findings indicate that the thermal aggregation of denatured β-Lg at the surface is important in the adsorption. More β-Lg was adsorbed at pH 4 than at pH 6.85. This suggests that the electrostatic interaction between β-Lg and the surface contributes to the adsorption behavior.