CAPILLARY ELECTROPHORETIC BEHAVIOR OF MILK-PROTEINS IN THE PRESENCE OF NONIONIC SURFACTANTS

The electrophoretic behavior of alpha-lactalbumin and beta-lactoglobul ins (A and B) in the presence of non-ionic surfactants was studied by capillary electrophoresis (CE), using a poly(ethylene glycol) coated c apillary 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 va riation permitted the estimation of the interaction between protein an d surfactant. The effect of surfactant type and concentration on the m igration 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 an d the surfactant type influence significantly the protein-surfactant i nteractions. (C) 1998 Elsevier Science B.V.