In a homogenizer for the processing of products to be homogenized, in particular foodstuffs incorporating dairy products, where the homogenizer is of the mixer type with a blade wheel(8) in a mixer tank (1) and a tubular perforated skirt (3) located radially closely outside the blades (10) of the blade wheel (8), that the skirt stationary relative to the rotor on the hub (6) is arranged axially displaceable also during the rotation of the blades (10) for displacement from a position in which a perforated skirt section (3.2) having a set of flow perforations or orifices (4) is located radially opposite the blades (10) of the rotor, to at least one other position in which another perforated skirt section (3.1 or 3.2) having another set of flow perforations or orifices in the form of perforations or orifices and/or slots (4) or at the most a part of a perforated skirt section is located radially opposite the blades (10), is achieved a homogenizer which is more simple to use than the known apparatus and which may serve more functions for homogenization of foodstuffs without transferring the foodstuff product to another tank during the adjustment of the mixer to the next function.