Thus, a primary aspect of the present invention relates to a method for the fractionation of a protein-containing mixture wherein the protein-containing mixture is selected from the group consisting of milk, milk derived products, milk derived raw materials, vegetable derived products, vegetable derived extracts, fruit derived products, fruit derived extracts, fish derived products, and fish derived extracts, said method comprising the steps of: a) optionally adjusting the pH of the mixture; b) applying said mixture to an adsorption column comprising an adsorbent, said adsorbent comprises a particle with at least one high density non-porous core, surrounded by a porous material, the adsorbent having a particle density of at least 1.5 g/ml and a mean particle size of at most 150 .mu.m; c) optionally washing the column; d) eluting at least one protein from the adsorbent.