Properties of extruded blends of wheat dried distiller grain flour with other flours

Zero, 10, 20 and 40% dried distiller grain (DDG) from wheat was blended with corn, potato, rice, and wheat flours at total moisture levels of 15 and 22% and extruded in a Brabender laboratory single screw extruder at three sets of barrel temperatures of 80, 130, 160°C; 100, 160, 210°C and 120, 190, 250°C at a constant screw speed (100 r.p.m.), screw configuration (3:1 compression ratio) and die size (3.175 mm). Resulting torque, yield, radial expansion (RA), longitudinal expansion index (LEI), density, water absorption index and colour were measured.
All the blends were successfully extruded over a wide temperature range. As the amount of DDG increased, in general torque, yield and RE decreased, and colour darkened while density and LEI increased. Wheat flour was the base material found to vary most from the above trends.