Process for de-boning meat or fish

Abstract

Material obtained from animals, poultry, or fish and containing edible flesh along with normally inedible relatively hard or tough components, such as bone, gristle, tendons, etc., is fed in ground condition into one 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. Such inedible components are compacted within the imperforate discharge end of the conduit by an extension of the conveyor screw prior to discharge following build-up and conveyance along the interior surface of the perforate portion of the conduit as a filter mat through which edible flesh is forced toward and through the perforations of the conduit to provide a substantially bonefree edible product. 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 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 particles of bone 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 finely ground material into the conduit by means of a high pressure pump. The discharged and normally inedible components can be slurried in a digestant liquid and the digested material recovered as a food product by the application of centrifugal force. In instances where some minute particles of bone are discharged with the fleshy components, they can be homogenized by subjecting such .[.flesh.]. .Iadd.fleshy .Iaddend.components to an attrition operation.

I claim: 
     
       1. A process for de-boning ground meat or fish material containing soft fleshy matter and .[.boney.]. .Iadd.bony .Iaddend.components, comprising the steps of introducing under pressure such a material into the feed end of a perforated de-boning conduit of circular cross-section and open for discharge of material at the opposite end, said conduit containing a rotary compression screw extending along its length and through the open discharge end thereof; conveying said material toward said discharge end of the conduit by means of said screw while maintaining said pressure, so as to compress said material within said conduit, whereby .[.boney.]. .Iadd.bony .Iaddend.components are retained in and passed along said conduit as a filter mat through which soft fleshy matter is forced toward and expelled through the perforations of the conduit; .Iadd.maintaining sufficient clearance between said screw and said perforated conduit to maintain a thin coating of said bony components on the inner wall portions of said conduit between said screw and said conduit; .Iaddend.selectively restricting .[.said.]. flow from the discharge end of the conduit circumferentially of and around the discharge end of said screw to increase the pressure within said conduit; and positively passing said filter mat through said open discharge end of said conduit circumferentially of and by means of said discharge end of the screw for discharge from the conduit. 
     
     
       2. A process according to claim 1, wherein the material is introduced into the conduit under pressure by means of a meat or fish grinder. 
     
     
       3. A process according to claim 1, wherein the material is introduced into the conduit under pressure by means of a pump. 
     
     
       4. A process according to claim 1, including the additional step of varying the extent of restriction of the discharge of the .[.boney.]. .Iadd.bony .Iaddend.components from the conduit. .Iadd. 
     
     
       5.  A process for de-boning ground meat or fish material containing soft fleshy matter and bony components, comprising the steps of introducing under pressure such a material into the feed end of a perforated de-boning conduit of circular cross-section and open for discharge of material at the opposite end, said conduit containing a rotary compression screw extending along its length and through the open discharge end thereof; conveying said material toward said discharge end of the conduit by means of said screw while maintaining said pressure, so as to compress said material within said conduit, whereby bony components are retained in and passed along said conduit as a filter mat through which soft fleshy matter is forced toward and expelled through the perforations of the conduit; maintaining sufficient clearance between said screw and said perforated conduit to maintain a thin coating of said bony components on the inner wall portions of said conduit between said screw and said conduit; said coating constituting a portion of said filter mat; said clearance being maintained on the order of four one-thousandths of an inch; selectively restricting flow from the discharge end of the conduit circumferentially of and around the discharge end of said screw to increase the pressure within said conduit; and positively passing said filter mat through said open discharge end of said conduit circumferentially of and by means of said discharge end of the screw for discharge from the conduit..Iaddend. .Iadd.6. A process for de-boning ground meat or fish material containing soft fleshy matter and bony components, comprising the steps of introducing under pressure such a material into the feed end of a perforated de-boning conduit of circular cross-section and open for discharge of material at the opposite end, said conduit containing a rotary compression screw extending along its length and through the open discharge end thereof; conveying said material toward said discharge end of the conduit by means of said screw while maintaining said pressure, so as to compress said material within said conduit, whereby bony components are retained in and passed along said conduit as a filter mat through which soft fleshy matter is forced toward and expelled through the perforations of the conduit; maintaining sufficient clearance about four one-thousandths of an inch between said perforated conduit and the flights of said screw to maintain a thin coating of said bony components on the inner wall portions of said conduit between said conduit and said flights of said screw; said coating constituting a portion of said filter mat; selectively restricting flow from the discharge end of the conduit circumferentially of and around the discharge end of said screw to increase the pressure within said conduit; and positively passing said filter mat through said open discharge end of said conduit circumferentially of and by means of said discharge end of the screw for 
     
     
        discharge from the conduit. .Iaddend. .Iadd.7.  A process for de-boning ground meat or fish material containing soft fleshy matter and bony components, comprising the steps of introducing such a material under pressure between about 5 to 250 pounds per square inch into the feed end of a perforated de-boning conduit of circular cross-section and open for discharge of material at the opposite end, said conduit containing a rotary compression screw extending along its length and through the open discharge end thereof; conveying said material toward said discharge end of the conduit by means of said screw while maintaining said pressure, so as to compress said material within said conduit, whereby bony components are retained in and passed along said conduit as a filter mat through which soft fleshy matter is forced toward and expelled through the perforations of the conduit; maintaining sufficient clearance between said perforated conduit and the flights of said screw to maintain a thin coating of said bony components on the inner wall portions of said conduit between said conduit and said flights of said screw; said coating constituting a portion of said filter mat; selectively restricting flow from the discharge end of the conduit circumferentially of and around the discharge end of said screw to increase the pressure within said conduit; and positively passing said filter mat through said open discharge end of said conduit circumferentially of and by means of said discharge end of the screw for discharge from the conduit..Iaddend.