Effects of Selected Tuber Crops Starch on Some Extrusion Properties of Fish Feed

This research evaluates the effect of feed formulation on fish feed properties with the aim of providing information on its water absorption and physical properties of the feed. The main objective of the study is to analysis the effects of the 3 tuber crops (dried cassava, potato and cocoyam flour) on the floatability of fish feed. The fish feed ingredients with varying percentage (40, 70 and 100) of starch from cassava, potato and cocoyam were extruded using a single screw extruder with constant screw speed (285 rpm). The resulting extrudates were subjected to extensive analysis of physical properties, which included moisture content, mass, surface area, volume unit density, bulk density and porosity. The water absorption properties include, the relative absorption rate (%), the water stability (%), the expansion ratio (%) and the floating ability rate (%) were also determined. There was a linear increment between the increase in starch with floatability and water absorption properties of cassava and cocoyam starch; however, a nonlinear decrease relationship existed in percentages (%) of potato starch. The formulation with 40% cocoyam has the highest floatability while the least floatability was observed from 100% potato at first 10 mins of observation. At 40% starches, 76.66% of cassava, 66.66% of potato and 100% of cocoyam afloat for the period of observation (10-120 mins). In conclusion, the formulation with 40% cocoyam was adjudged as the preferable feed composition based on its floatability. From the result, it can be recommended that cocoyam starch support the floatability of fish feed.