What top considerations I should keep in mind when evaluating a potential pet food extrusion system?
It is important to note that the complete extrusion system, inclusive of the material handling and feeding/metering of the raw ingredients prior to the extruder, and of course the extruder and downstream ancillaries involves many components. It is imperative to evaluate the system and supplier who can not only provide the complete integrated system to ensure end product quality, but can also provide expertise and engineered designs which emphasize food safety and cleanability in design. The ability to minimize any risk of contamination, as well as minimize downtime for cleaning and product changeover by including proper design techniques in the extruder and material handling equipment can make a huge difference in the process, product safety, and overall process efficiency. These involve several key considerations including:
Wear solutions for extruders: It is important to evaluate the extruder’s design and materials of construction (for example, stainless steels with 16% or greater Cr) from a safety standpoint. The use of the proper steel for contact surfaces can be overlooked. Other exposed surfaces should be coated (nickel plating on outside surfaces) or covered properly. Bearings and seals should be designed for proper cleaning (there should be cleanout areas behind seals and packings, shafts should be resistant to wear or grooving from seals). The Coperion ZSK extruders provided to the pet food industry include special metallurgical construction which makes them ideally compatible for the caustic solutions used in a wet wash-down environment. This composition allows for complete CIP of the extruder and also is critical for wear resistance, which may occur due to the abrasiveness of some pet food formulation.
Ingredient Material Handling and Feeder Designs: Design innovations are also available for all the pneumatic conveying and feeder materials handling systems prior to entering the extruder. High accuracy ingredient feeders, such as the Coperion K-Tron screw feeders are ideal for addition of probiotics and vitamins to the pet food mix. Additional design features can easily be incorporated into the feeder design to ensure quick changeover times and cleanability. In addition, the pneumatic conveying systems which transfer the raw ingredients to the pet food process include innovations such as the Coperion K-Tron Sanitary Filter Receiver (SFR). This pneumatic receiver has been completely designed and engineered based upon in-depth discussions with pneumatic conveying receiver users in the pet food and food industries. The unique top entry and special custom engineered side access filter assembly of the SFR allows for high efficiencies, with minimal degradation of the product due to decreased can velocities, and extremely high access to all internal areas of the receiver for cleaning. The reduction in time alone for complete filter change out and cleaning compared to typical side tangential inlet, top removal cartridge or bag filter designs can be significant to overall process and product changeover times.
Finally, the design of unique European Hygienic Engineering Design Guidelines (EHEDG) rotary and diverter valves for ingredient handling systems also allows for complete cleaning of the system (CIP and COP), with proven capabilities through agar/spore testing of completely contaminant free cleaning and access ability.