PolyOne is designed to fulfill process requirements of the pet food and aqua feed industry as capacity, screw speed, torque and pressure. The double-stage preconditioner separates the mixing zone from the retention zone. This ensures optimal, intensive mixing at high screw speeds and gentle retention across a narrow time range at a low screw speed. The design of the double-stage preconditioner is such that the material inlet is vertically positioned above the outlet. A sanitary startup valve separates product streams. Uncooked product flow can be separated, and the multifunctional single-screw extruder system can be used to sterilize product streams without contaminating the extruder die and the cutter.