Sterilization is one of the key functions of dry extrusion
Recently, I was contacted by one of our customers who has been successfully producing shaped feeds with our MS3000 Model medium-shear dry extruder for a number of years. The reason for the call centered around salmonella found in the final product.
In addition to other ingredients, they have also been using meat and bone meal in their formulations. It turns our that these ingredients were found to be the source of the salmonella. It is a well-known fact that one of the key functions of medium-shear dry extrusion is sterilization.
No live bacteria can survive high temperatures and pressure. And in this case, the solution would be to source a better quality ingredient or solve the problem entirely by running the “bad” ingredient through a medium-shear dry extruder.
If someone comes across a problem like this when making shaped products such as pet food or fish feed, it is important to note that problematic ingredients should be run separately for sterilization purposes. The reason for this centers around the presence of vitamins in complete formulations that will be impacted by high temperatures. Once the problematic ingredient has been stabilized though medium-shear dry extrusion, it can be safely mixed with other components of the formulation and processed through the MS3000 extruder to produce high quality shaped feeds.
If you have any questions about your formulation or best practices, please reach out to our team.