FACTORS AFFECTING THE FLOATING AQUATIC FEED PELLETS QUALITY

Abstract

Production of high quality floating aquatic feed has in recent years accounted more than 65% of the market needs of fish feed. Most of fish feed factories have tended to develop their production lines by adding extrusion units to produce floating fish feed after increasing demand from farmers for this type of feed for many reasons, such as :the high conversion rates than sinking feed , decreased the consumed amounts of fish feed in aquaculture farms about 30%,easy to follow the fish vitality during feeding process and reduced the chances of infection by fish diseases. The parameters under studied were water addition site (just pre-conditioner- just extruder barrel zones -pre-conditioner and extruder barrel zones), extruder screw configurations profile (high configuration shear, medium configuration shear and low configuration shear) and drying cooling process after extrusion (cooling only and drying with cooling). Steam percentage of (13%) added into the pre-conditioner for all study treatments as constant parameters. The floating die specifications of the extruder were L/D ratio of 30:1, land length diameter of 2.5 mm and the die consists of 10 holes each outer diameter of 2.5mm. The optimum running parameters for proceeds floating aquatic feed were water addition into both pre-conditioner and extruder barrel zones (9%PC+5%EX), high shear screw configurations profile, and drying process for 10.5 min at air temperature of 210oC with cooling process for 5.5 min. The result of extruder performance and floating pellets quality measurements for these parameters were, extruder production rate of 196.6 kg/h, extruder specific mechanical energy (SME) of 130.7 kJ/kg, floating pellets bulk density of 332.9 kg/m3, final product pellets expansion ratio of 2.28, and floating pellets water stability of 100% after 33 h in water.