Effect of Varying Levels of Moisture Content on the Extrusion Properties of Asian Seabass (Lates calcarifer) Feed in Twin Screw Extruder

The present study was conducted to study the effect of varying levels of moisture content on extrusion properties of CIBA developed Asian seabass (Lates calcarifer) feed. The effect of addition of moisture was studied at 10%, 15%, 20%, 25%, and 30%. The trial was carried out in a pilot scale twin screw extruder (M/S. Jinan saibainuo Technology, China) with a capacity to produce 250 kg per hour. All the machinery parameters and feed processing factors were kept constant but for the moisture content. All the six feed mix were subjected for extrusion and the trial was repeated thrice. The results of the extrusion trials revealed that there was no extrusion of the feed mix containing moisture up to 15% and the extrusion process has just started at 20% moisture level. Feed mix containing 25% and 30% moisture showed efficient extrusion resulting in good expansion of the finished product. Moisture addition of 35% showed difficulty in an operation as the feed material is getting choked in the extruder. As the level of moisture content increased the bulk density with floating buoyancy was observed in the feed mix containing 25% and 30% moisture. Feed pellet extruded at 25% and 30% moisture showed significantly better water stability compared to the rest. In the second trial effect of preconditioning on the extrudate properties revealed that conditioning for 30 minutes helps in improving the extrudate properties. The results revealed that a total moisture content of 25-30% is optimal for the better extrusion and preconditioning for 30 minutes had a beneficial effect on the extrudate properties of CIBA developed seabass feed with 40% protein.