Twin screw preconditioner unit and method

A dry raw cereal material having a starch fraction is fed into the inlet (38) of a twin screw preconditioning unit (10). The dry material is rapidly advanced and mixed in the first two zones (31, 32) and conveyed into a third zone (33). Water is introduced by ducts (42) and is admixed with the dry material to form a well mixed wetted cereal material. The screws (14, 16) include blank segments (14c, 16c) having radially extending pins (40) to create a material plug in the barrel (30) of the preconditioning unit (10). Steam is added to the wetted material in the next zone (34) to form a heated wetted cereal material which is worked in the fourth zone (34) to form a heated precooked non-continuous cereal compacted dough material which is generally maintained below its gelatinization point. The dough material exits the outlet (41) of the preconditioning unit (10) and enters a low shear extended time cereal cooker (46) which finish cooks the dough material to a fully cooked cereal dough which is formed into desirably shaped and sized pellets.