State of the art technology in aquatic feed and pet food production

Extruding feed is primarily a matter of cooking the starch. The better the starch is cooked, the better the quality of the feed. However, it is equally important to control the expansion of the feed, thus influencing density which determines both sinking and floating properties.

By controlling the specific mechanical energy (SME) of the screw configuration on the extruder, it is possible to reach optimum gelatinization, thus achieving a product with improved digestibility and increasing growth rate.

On most new extruder designs, screw configuration can be optimized with the SME necessary to match specific product requirements such as those with high fat/oil content, internal oil or similar products with high nutritional value. Screw configuration can be optimized to apply more SME by implementing the following components:

• Screw design and geometry

• Shear locks

• Kneading blocks

• Reverse elements

An optimum screw configuration is not always capable of applying sufficient SME to produce a given product. Often it is also necessary to optimize other parameters that can be used to increase the SME supply in the extruder:

• Screw speed

• Open area of venturi die

• Open area of die plate

• Extruder capacity