The invention relates to a separating apparatus for separating a mixture of materials of different flowability for preparing foodstuffs. The apparatus includes a hollow drum having a perforated circumferential surface around a portion of which is wrapped an endless presser belt forming a compression zone for the material to be processed. The belt is pressed against the drum by a presser roller having a hub body around which a tubular cylindrical body forms the roller surface. The cylindrical body is supported in its middle portion by spherical supporting element mounted on the hub body. Thus when the belt is subjected to non-uniform stresses due to the uneven consistency of fed material which in turn causes the deformation and unparallel rotation of the drum and the presser roller, the cylindrical body automatically adjusts its position on said spherical supporting element to restore parallel motion.