Responce Surface of Drying Parameters on Some Physical Properties Related to Floatability of Extruded Fish Feeds

Abstract

Fish feeds drying plays a major role in the aquaculture industry by ensuring preservation and quality of feed for effective growth and development of farmed fish. Optimization the drying parameters such as drying temperature, drying air velocity and relative humidity plays a crucial role in achieving Response Surface Methodology is a useful to optimized variables/factors more practically as compared to just the statistically significant test for a particular point. The aim of this research to optimize the drying process of an extruded fish feeds which affect the floatability of the feeds. 2000 g of the extruded feeds was dried in a continuous flow belt dryer. The experiments were performed at air temperature of 60, 70, 80, 90 and 100°C, air velocities of 0.7, 0.8, 0.9, 1.0 and 1.2 m s-1 and drying belt linear speeds of 50, 55, 60, 65 and 70 rpm. The dried extruded fish feed was subjected to extensive physical properties which are: unit density (kg m-3), water stability (%), sinking velocity and relative absorption ratio. The surface response of each of this physical property of the dried extrudates’ were determined. The result shows that the operational parameter can optimally explain about 90.45%, 93.72%, 95.98% and 70.77% change in the density, water stability, sinking velocity and the relative absorption ratio respectively of the extrudate via quadratic function. The optimum predicted values for air temperature of 97.49°C, conveyor belt speed of 50 rpm and air velocity of 1.10 m s-1 were obtained for the dryer within the range of the input parameters.