Effect of extrusion temperature, moisture content and screw speed on the functional properties of aquaculture balanced feed

The aim of this study is to analyze the effect of feed moisture content, temperature, and screw velocity on the functional properties of extruded feeds for aquaculture with a bean flour and soy protein base. Fishmeal was substituted at different concentrations of bean flour or soy protein. Later, the diets were extruded and the expansion index, apparent density, and the extrusion sinking velocity were analyzed and an optimization of the process was carried out. The extrusion moisture content has an effect (p < 0.05) on the extrusion expansion index. The extrusion conditions were optimized with 93, 186 and 279 g/kg of bean flour or soy protein. The diets with soy protein require a higher amount of moisture, higher temperature, and a higher screw velocity than diets with bean flour, to obtain diets that are within range of the physical characteristics similar to commercial diets.