Process for the separation of fat from animal skins

Abstract

Raw or partially cooked animal skins containing fats and oils from which the surface hair has been removed are ground into particles and fed into the end of a perforated conduit that has a conveyor screw therein which progressively decreases in conveying capacity from the feed end of the conduit to an imperforate discharge end thereof. Without the application of heat, the skin particles are compacted within the imperforate discharge end of the conduit by an extension of the conveyor screw prior to discharge following buildup and conveyance along the interior surface of the imperforate portion of the conduit through which edible fats and oils are forced toward and through the perforations of the conduit to provide a substantially fat free animal skin. The discharge passage surrounding the extension of the conveyor screw can be varied in size preferably by a tapered ring that is movable back and forth axially of the conveyor screw extension, and preferably the spacing between the conveyor screw and conduit is variable. The forward faces of the conveyor screw flights are preferably concave to provide a forwardly projecting circumferential overhang that tends to keep the particles of skin near the axis of the screw, and the conduit wall thickness is unusually thick so as to withstand high pressures. Unusually high production rates can be obtained by feeding ground animal skins into the conduit by means of a high pressure pump. The discharged fats and oils can be rendered to provide an edible animal fat and the defatted skin discharged can be treated for the recovery of high quality gelatin.

Dependencies are inferred from the claim text.