Effect of Drying Parameters on the Physical Properties of Extruded Fish Feed

Abstract

Commercial catfish feed is sometimes manufactured through extrusion, usually are of high moisture content which cannot be stored or transported without it being damaged, hence, the need for effective drying of fish feed. Fish feed was formulated, mixed, extruded (single screw extruder), dried (mechanical convective dryer) and evaluated upon to examine the impact of the drying parameters (air drying temperature and air-drying velocity) and some physical properties of the fish feed. Five levels of drying air temperature (40° C, 50° C, 60° C, 70° C and 80° C) and three levels of drying air velocity (1.0 m/s, 1.5 m/s and 2.0 m/s) were used during the drying experiments. The final moisture content reduces with increase in drying air temperature and drying air velocities. The drying temperature does not significantly affect the unit density and porosity. Bulk density reduces with increased drying air temperature and drying air velocity. The extrudate porosity increases with drying air temperature. The drying air velocities does not significantly affect the sinking velocity and porosity. The optimum floatation time is from the feed dried at 1.5 m/s drying air velocity and 80oC drying air temperature.