DisplayTitle

Effects of Protease and Urea on a Granular Starch Hydrolyzing Process for Corn Ethanol Production

¹Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, 360G AESB, 1304 West Pennsylvania Avenue, Urbana, IL 61801. Mention of trade names or commercial products is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture or University of Illinois at Urbana-Champaign. ²Eastern Regional Research Center, Agricultural Research Service, USDA, 600 E. Mermaid Lane, Wyndmoor, PA 19038. ³Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 367 Bevier Hall, 905 S. Goodwin, Urbana, IL 61801. ⁴Corresponding author. Phone: 217-333-9510. Fax: 217-244-0323. E-mail: vsingh@illinois.edu

The dry grind process using granular starch hydrolyzing enzymes (GSHE) saves energy. The amount of GSHE used is an important factor affecting dry grind process economics. Proteases can weaken protein matrix to aid starch release and may reduce GSHE doses. Two specific proteases, an exoprotease and an endoprotease, were evaluated in the dry grind process using GSHE (GSH process). The effect of protease and urea addition on GSH process was also evaluated. Addition of these proteases resulted in higher ethanol concentrations (mean increase of 0.3–1.8 v/v) and lower distillers' dried grains with solubles (DDGS) yields (mean decrease of 1.3–8.0% db) compared with the control (no protease addition). As protease levels and GSHE increased, ethanol concentrations increased and DDGS yields decreased. Protease addition reduced the required GSHE dose. Final mean ethanol concentrations without urea (15.2% v/v) were higher than with urea (15.0% v/v) in GSH process across all protease treatments.