Extruded Feed

This is Ridley Aquafeeds manufacturing process which is broken down in to 6 steps;

Storage, preconditioning, drying, oil addition, cooling and packing.

 

 

 

Purchased raw materials are delivered into the mill and following quality control testing is put into a silo. These are locked off to prevent the addition of an incorrect raw material. When a recipe is required to be manufactured it is weighed out in two tonne batches and finely ground. This provides improved physical and nutritional quality of the finished feed. This “mash” of mixed raw materials is then stored in a silo prior to the preconditioner.

 

This is the main cooking process in the manufacture of feed. The mash needs to be cooked in order to make a discrete pellet. Starch in the form of wheat needs to be cooked or gelatinised while proteins in the diet are plasticised. This forms the matrix that holds the structure of the pellet.

 

As the mash is added to the preconditioner, steam, water or oil can be added to start the cooking process. After a few minutes the heated mash passes to the extruder where more steam water or oil can be added. A series of screw elements knead the mix and create mechanical heat and pressure. This cooks the starch and other raw materials while moving material to the die end of the extruder.

 

The very hot product is extruded through a die, which is changed depending on the size of pellet or the buoyancy of the feed. The extrudate is then cut with a spinning knife to the required length. Due to the sudden release of pressure the product expands rapidly. This expansion creates holes, which are filled with oil in the vacuum coater or left empty which allows a pellet to float on water.

 

As the product leaves the extruder it is moist (between 20 and 25% moisture) and this needs to be dry to make the pellet shelf stable therefore preventing mould growth. It also allows the pellet to harden to aid with handling on farm. The starch in the pellet continues to cook in the dryer so it is very important to control the heat so the product does not over dry and burn. On leaving the drier the product is about 8% moisture (depending on the product) and is ready for oil to be added.

 

The dry hot pellet enters the vacuum coater where oil is added. The oil is applied under vacuum as this allows excellent penetration of oil and makes the product dry to the touch. Using this technology it is possible to have a very high content of oil in a small pellet.