Evaluation of a Counter Current Cooling System of a Fish Feed Extrusion

Abstract

This study explores the application of a counter-current cooling system to manage the excess
heat generated during fish feed extrusion, a process critical for producing high-quality,
nutritionally balanced feed. During extrusion, elevated temperatures caused by friction can
degrade nutrients, damage product structure, and lead to economic losses. To address this,
the research employed a counterflow cooling mechanism designed to enhance thermal regulation
and product quality. An optimal experimental design approach was adopted using
Response Surface Methodology (RSM) to analyze the influence of three key process variables:
screw speed (150, 200, 250, and 300 rpm), die size (4, 6, and 8 mm), and water flow
rate (25, 50, 75, and 100 Lmin¹). Response parameters included extrudate temperature,
cooling efficiency, and bulk density. The study incorporated replication and error analysis
to improve the reliability of optimization results. Maximum extrudate temperature reached
319°C at the highest screw speed, while the optimal conditions were at screw speed of
254.97 rpm, 5 mm die size, and 100 Lmin¹ water flow resulted in effective heat reduction
and desirable product characteristics with a desirability score of 0.633. The study also
highlights the adaptability of the proposed cooling system for various food matrices, including
high-protein and fortified blends. Additionally, it considers scalability, operational
cost, and maintenance aspects, suggesting that the system is practical for both small- and
large-scale aquafeed production. Overall, the counter-current cooling approach demonstrated
a significant improvement in process control, product safety, and energy efficiency,
offering a sustainable solution for modern aquafeed manufacturing.