More Efficient Ethanol Production Closer to Reality

Producing fuel ethanol from grains at low temperatures may be more feasible, thanks to improved enzymes developed in the laboratory, Agricultural Research Service scientists reported Tuesday at the American Chemical Society meeting in San Diego, Calif.

When grains are processed into ethanol, starch granules are cooked at 105 degrees Celsius (about 223 degrees Fahrenheit) to convert the starch to a form that enzymes can degrade into simple sugars. About 10 to 15 percent of the processing energy required to make ethanol goes towards providing the heat used to cook the starch. Producers, of course, aim to use as little energy as possible to make the fuel.

Researchers at ARS’ Western Regional Research Center in Albany, Calif., have developed variants of a natural starch-degrading enzyme that breaks down starch 50 times faster than the original enzyme in the laboratory, at 37 degrees Celsius (about 99 degrees Fahrenheit). Enzymes with greater activity at low temperatures could facilitate development of more energy-efficient methods of ethanol production.

These findings could also provide additional outlets for wheat, barley and other grains, and support efforts to increase nonfood uses of agricultural products. Executive Order 13134, signed by the president in 1999, aims to triple use of biobased products and bioenergy in the United States by 2010.

At the ACS meeting Tuesday, ARS chemist Dominic Wong and ARS chemical engineer George Robertson co-chaired a symposium on the application of combinatorial chemistry in agriculture and food processing.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.

Scientific contact: Dominic Wong or George Robertson, ARS Western Regional Research Center, Process Chemistry and Engineering Research Unit, Albany, Calif.; phone (510) 559-5621, fax (510) 559-5818, dwsw@pw.usda.gov or grobertson@pw.usda.gov.