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Effect of Single-Screw Extruder Die Temperature, Amount of Distillers' Dried Grains With Solubles (DDGS), and Initial Moisture Content on Extrudates¹

¹Request to publish this research article approved by Agricultural Experiment Station, South Dakota State University. Journal number 3405, dated 01/02/2004. ²Research associate, associate professor, and associate professor, respectively, Agricultural and Biosystems Engineering, South Dakota State University, Brookings, SD 57007. ³Corresponding author. Phone: 605-688-5661. Fax: 605-688-6764. E-mail: muthukum@sdstate.edu

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.