The present invention relates to a method for separating at least one soluble protein fraction from an aggregated casein-containing material, the method comprises the steps of: (i) providing the aggregated casein-containing material； (ii) Contacting the aggregated casein-containing material with a chromatographic support allowing one or more soluble protein(s) present in the aggregated casein-containing material to be retained by the chromatographic support； (iii) Obtaining a permeate fraction from the chromatographic support comprising aggregated casein； (iv) Optionally washing the chromatographic support； (v) Subjecting the chromatographic support to at least one elution buffer obtaining at least one soluble protein fraction from the chromatographic support； and wherein the chromatographic support comprises one or more mixed-mode ligands capable of binding the soluble proteins from the aggregated casein-containing material.
