EFFECTS OF DRYING PARAMETERS ON SOME PHYSICAL PROPERTIES OF A DRIED EXTRUDED FISH FEEDS

Abstract

Extruded feed is the most typical form of animal feed produced in the world as a result of its numerous advantages over sinking fish feeds. In Nigeria most feeds produced are not floating as a result of poor drying of the feeds. The quality of fish feeds is affected by the physical properties. In this study, the fish feed was formulated and extruded using a single screw extruder, dried in a continuous flow belt dryer for 270 minutes at drying air temperatures (60, 70, 80, 90 and 100 ^oC) drying air velocities (0.7, 0.8, 0.9, 1.0 and 1.2 m/s) and belt speeds (50, 55, 60, 65 and 70 rpm). The density, buoyancy and water stability of the processed feeds were determined. The results show that the minimum value of 545.60 kg/m³ and 20% were obtained for density and buoyancy of the dried extrudate respectively when the machine was operated at 60 ^oC, 0.8 m/s and 70 rpm. The maximum values for density, buoyancy and water stability were 55kg/m³, 99.9% and 65.56% respectively, of the dried extrudate. The effect of the processing conditions on the physical properties (density, buoyancy and water stability) of the feed was observed to be significant (p < 0.01).The drying air temperature and air velocity were found to have a major effect on the buoyancy and water stability of the dried extrudate with belt speed having the least effect. Furthermore, the belt speed was found to have a major effect on the density while the drying air temperature and air velocity have minor effects on the dried extrudate density.