Evaluation of Physical Properties of Feeds with Different Pellet Size and Extrusion Conditions

This work present a useful information on the effect of different temperature profile on the barrel during the extrusion process to the physical quality properties of the extrudates. The feed mixtures were extruded using a twin-screw extruder. The barrel temperature profile was set at 110o C for cooking extrusion process and no additional heal for cold process with two different size of extrudates, 2 and 4 mm. The physical properties of the extruded diets (durability index, expansion ratio, sinking velocity, water stability and water absorption index) were investigated. The results showed that cooking process provide a better durability and water stability index. Sinking velocity of cooking process was longer than cold process and the highest value for water absorption index was found for 2 mm extrudates processed with high temperature. The higher expansion ratio was found in the bigger size of extrudates

processed with high temperature compared to other treatment. Overall, the cooking extrusion profile provides a better option for aquaculture industry. A future study investigating the effects of feed composition and several temperature profile on the barrel and die for aquafeed production would be appropriate.

Keywords: Aquafeed, cooking extrusion, cold process, physical properties