In this edition, how about we discuss a different view on extrusion of petfood products. Previous discussions on four main areas of extruding a product were on formula, hardware, operations conditions and final product specifications. Which comes first, usually? I am sure contract manufacturers can answer this one as well as production managers. It is normally the final product specs that come first.
Working with various nutritionists, some begin the discussion with the extruder operators. What can the machine do and what can you do within reason. Obviously, this requires a knowledge of extrusion and what can be done, each case can be different as each extruder is possibly different. Been in many production facilities with multiples of the same extruder model with different main drive motor sizes and different conditioning cylinders. With all of the other possibilities, these questions are asked on the intended production machine. Extruders are tools and best used as designed for maximum efficiency. Lowest starch level, highest fat level, product dimensions, expansion ratios extruder barrel configuration, approximate capacities and others would allow discussions to plan and insure the best possible chance to make a new product. Are these answers based on when the extruder components are new or in a semi worn or completely worn state? Computer controls allow for recording running conditions at different wear conditions allowing for a better chance making similar spec products over the life of the parts. Running conditions allow for this with liquid additions, dies, screw speed, flow restriction control and capacity adjustments to hit the specs.
The trick is to know the trends and how to react when the specs move from the intended outcome. The hard part to explain is to determine which way to go. For example, steam injection in the extruder barrel, if you add more and expansion increases, add too much and the product might blow apart and have a rough surface. So, the general answer is increase or decrease steam. Another is cook. You can get the idea at the extruded discharge by placing in water, if it swells about two times, I would predict you are cooking well. Now, in modern times, instrumentation checks temperature, expansion, moisture levels and can even record specific mechanical energy inputs give a good indication the product is made under a set of specifications, and this will predictably be in ranges set. It is considered as a must to meet the FDA petfood production restrictions in cleanliness. There are many old school methods, and some are still using them, current plant and equipment designs place the plant and quality control in management hands. Operators still need to know how to react but within ranges set to maintain capacity and quality.
