Determination of native and denatured milk proteins by high-performance size exclusion chromatography

High-performance size exclusion chromatography on a TSK 3000 SW column was used to separate and quantify the individual milk proteins in their native and/or denatured state. Quantitation of the individual native whey proteins within +/- 10% was achieved. The denatured proteins were dissociated into their monomer units by using sodium dodecyl sulphate and beta-mercaptoethanol. A good separation of the whey protein monomers was achieved and the quantitation of the individual whey proteins within +/- 10% was possible. Under these conditions, alpha s1- and beta-casein were eluted as one peak, whereas kappa-casein and gamma-casein were eluted in the same position as beta-lactoglobulin and alpha-lactalbumin respectively. A method for calculating the areas and hence the concentration of the individual proteins in a mixture of casein and whey proteins is described.