Developing New Processes for Enzyme Use in Ethanol Production

9 April 2007

USDA Researchers are developing new processes for the use of proteases from microbial and fungal sources to enhance the fermentative production of ethanol. The enzymes make more nutrients available for the yeast, expediting fermentation of sugars. Protease enzymes can also facilitate the process of dewatering the solids that remain after the ethanol has been extracted.

David Johnston, from the US Department of Agriculture’s Agricultural Research Service and Vijay Singh, an agricultural engineer at the University of Illinois, recently conducted a field trial at a small wet-milling facility in Panang, Malaysia.

They soaked corn in water for several hours and then applied the enzymes provided by Genencor International. The scientists found that adding enzymes during processing increased starch recovery, just as it had in laboratory trials.

The work is part of a five-year research project that began in 2004, the objective of which is to develop new, cost effective, alternative methods and engineering processes for corn processing and fractionation using enzymes, immobilized enzymes and other environmentally sustainable processes that maximize the yields of products and co-products  and increase co-product market diversity and value while eliminating hazardous processing aids, such as sulfites.

Resources:

• “Use of Proteases to Reduce Steep Time and SO(2) Requirements in a Corn Wet-Milling Process”; David B. Johnston and Vijay Singh; Cereal Chem. 78(4):405-411

• “Comparison of Raw Starch Hydrolyzing Enzyme with Conventional Liquefaction and Saccharification Enzymes in Dry-Grind Corn Processing”; Ping Wang, Vijay Singh, Hua Xue, David B. Johnston, Kent D. Rausch, and M. E. Tumbleson; Cereal Chem. 84(1):10-14 DOI: 10.1094/CCHEM-84-1-0010