Effect of Starch Sources on Properties of Extrudates Containing DDGS

Abstract

Various levels of DDGS (20, 40, and 60% wb) were blended with starch sources (cassava, corn, and potato), and other ingredients to produce an iso-nitrogenous feed (28% protein) at varied moisture contents (15, 20, and 25% wb). The feed blends were extruded in a single-screw extruder at a preset screw speed of 130 rpm (13.6 rad/s) with three temperatures profiles 90–100–100°C, 90–120–120°C, and 90–140–140°C. The effect of these variables on processing conditions (extruder torque and die pressure) and other extrudate properties (expansion ratio (ER), unit density (UD), color (L*, a*, and b*), sinking velocity (SV), water absorption, water solubility, and pellet durability indices (PDI)) were analyzed. For all the three starch extrudates, changing the levels of DDGS, feed moisture content, and extruder barrel temperature had a significant effect on SV, PDI, a*, and b* values at α = 0.05.