Effect of Single‐Screw Extruder Die Temperature, Amount of Distillers' Dried Grains With Solubles (DDGS), and Initial Moisture Content on Extrudates

Corn distillers' dried grains with solubles (DDGS) was extruded with corn meal in a pilot plant single‐screw extruder at different extruder die temperatures (100, 120, and 150°C), levels of DDGS (0, 10, 20, and 30%) and initial moisture contents (11, 15, and 20% wb). In general, there was a decrease in water absorption index (WAI), water solubility index (WSI), radial expansion, and L * value with an increase in DDGS level, whereas a * value and bulk density increased. Increase in extruder die temperature resulted in an increase in WSI and WAI but a decrease in L * and bulk density. Peak load was highest at 30% DDGS as compared with 0, 10, and 20% DDGS extrudates. Die temperature of 120°C and initial moisture content of 20% resulted in least peak load. The a * value remained unaffected by changes in extruder die temperature. Radial expansion was highest at extruder die temperature of 120°C. Maximum WAI, WSI, radial expansion, and L * value were obtained at 15% initial moisture content. An increase in initial moisture content, in general, decreased L * value and bulk density but increased a * value of extrudates.