Is a cooker or toaster needed before extrusion?
Recently, I had many clients and prospects ask about having a cooker just before extrusion. While this is entirely up to the client, it is our duty to educate about all of the processes involved in an extrusion plant.
With our extruders, the short answer is no, there is no need for a cooker before high-shear dry extrusion. The optimum time and temperature takes place in the extruder.
In addition, through the magic of high-shear dry extrusion, short cook time allows for very high digestibility. As shown on the chart below, the more time it takes for the soy to heat up, the lower the lysine. Extrusion is only 20 seconds, and that’s the key for having quality ExPress® soy cake. Adding a cooker before extrusion will mean lowering the lysine by heating it for a longer period of time.
Furthermore, a toaster or cooker before extrusion tends to make uneven meal since it heats up the outside of the soy instead of the inside, keeping it raw in the middle. This is not good for digestion.
Since we are talking about what can be done before extrusion to improve the process, there are two things I highly recommend take place before extrusion:
- That the soy is between 9-11% humidity before extrusion. This will allow the right humidity for cooking of the soy in the shaft, and will allow the press to work better.
- Hammer meal for a coarse mill before extrusion. The extruder can work without this, but it will result in a more homogeneous meal and provide cost savings.
Please don’t hesitate to contact us with any questions, will be glad to assist you.