Capillary electrophoretic behavior of milk proteins in the presence of non-ionic surfactants

The electrophoretic behavior of alpha-lactalbumin and beta-lactoglobulins (A and B) in the presence of non-ionic surfactants was studied by capillary electrophoresis (CE), using a poly(ethylene glycol) coated capillary column. The surfactants (Tween 20, Brij 35 and 78) were used as buffer additives. The separation is based on the difference in the strength of protein-surfactant association complexes, which results in a change of the effective electrophoretic mobility. The modification of the electrophoretic mobilities of proteins was observed and this variation permitted the estimation of the interaction between protein and surfactant. The effect of surfactant type and concentration on the migration behavior of protein in CE is discussed. It is found that the retention behavior of the milk proteins (the alpha-lactalbumin and the beta-lactoglobulins) in CE is very different. The pH of the buffer and the surfactant type influence significantly the protein-surfactant interactions.