FACTORS INFLUENCING THE QUALITY OF EXTRUDED SINKING AQUATIC FEED PELLETS

Abstract

Aquatic feed production is an important application of extrusion processing. This study focused on the effect of formulation particle size and processing parameters on physical and stability characteristics of extruded sinking shrimp feed. The parameters studied were ration particle size (0.8 and 1.2 mm), single screw extrusion die profile (land length of 2.5 and 5.0 mm; die output area percentage of 4.5 and 6.7%), and drying conditions (cooling only and drying followed by cooling). The single screw extruder die L/D ratio was 30: 1, with outlet diameter of 2.5 mm. The same formulation was also pelleted by a ring die pellet mill with die L/D ratio of 13.3: 1 and diameter of 2.38 mm, followed by only cooling of pellets. The quality of feed obtained by extrusion and pellet mill were evaluated. The optimum parameters for sinking feed production by extrusion were - formulation particle size of 0.8 mm, die profile with 5.0 mm land length and 6.7% die output area percentage, and drying for 10.5 min at 210oC followed by cooling for 5.5 min. The process and pellet quality data for these parameters were 213.2 kg/h production rate, 68.4 kJ/kg specific mechanical energy (SME), 529.4 kg/m3 pellet bulk density, 6.7% final moisture content, 99.8% pellet durability, 100% pellet sinking percentage after immersion for 21-24 h, and water stability of 100% after 30 min, 90% between 30–60 min and 80% between 1-24 h. The corresponding pellet mill results were 444.1 kg/h production rate, 23.9 kJ/kg SME, 658.3 kg/m3 bulk density, 98.4 % durability, 100 % sinking percentage after 45 min, and water stability of 40% after 15 min, 10% after 30 min and 0.0% after 1 h. Results indicated that SME was the most important factor affecting pellet quality, and better quality sinking aquatic feed could be produced using single screw extrusion processing as compared to pellet mill processing. PRACTICAL APPLICATION The manuscript make focus on the physical and mechanical factors of single screw extruder affecting the sinking aquatic feed pellets quality by studying the die holes profile , formula particle size and drying - cooling profile , the results are very important for extrusion industries to determine the optimum conditions of formula and extruder to produce high quality of pellets, the study used new measurements , it's very important for industries quality control such as the pellets water stability and sinking percentage