The feeding zone of the extruder is that area where the low density discrete particles of raw material are transported into the extruder barrel inlet. This low density, often preconditioned material, is then transported into the interior of the extrusion processing chamber. The flow channel of the screw is typically not filled in this zone due to the air entrapped in the incoming material. The incoming material is compressed slightly in this zone with the air being expelled. Water is typically injected into the barrel in the feeding zone to facilitate textural development, viscosity development, and to enhance conductive heat transfer.