What is extrusion?

Extrusion is a process whereby material is pushed through a restricted area in order to change the characteristics of the material. Extrusion is used to form steel and plastics into sections such as pipes. It is also used in the food industry for making pasta, biscuits and breakfast cereals.

In the extrusion process used to compress animal feed such as soya and maize, a series of flights rotating at high speed and pressure cause structural changes in the qualitative measures of the material. The temperature of the material increases. As a result of mechanical shearing, friction and steam creation, the product is forced through the die openings.

Extrusion makes the product easier to digest, and due to the high temperature (approximately 150°C) bacteria are killed and the product disinfected. The high temperature also breaks down the trypsin inhibitors found in raw soya beans, creating a high protein and energy feed suitable for cattle, poultry or even humans.