Patent ID: 8827539

Claim:
A twin-screw cooking extruder comprising: an elongated, tubular barrel presenting a material input and a spaced material output; a restricted orifice die disposed across said output; and a twin-screw assembly located within said barrel and including first and second elongated, axially rotatable screws each having an elongated shaft with outwardly extending helical flighting along the length of each shaft, the flighting of each shaft being intermeshed with the flighting of the other shaft, said first and second screws being substantially coextensive in length, the flighting of each of the first and second shafts presenting a pair of axially spaced apart sections of short pitch length, and an intermediate section having a pitch length greater than the pitch lengths of either of said short pitch length sections, said intermediate section having an axial length greater than four times the length of either of said axially spaced apart sections, said screws having an S D /R D ratio of from about 1.9-2.5, wherein S D is the outermost screw diameter of the flighting of said first and second shafts, and R D is the root diameter of said first and second shafts.