Partnership Could Oust Off-Flavor in Fish

By Tara Weaver-Missick
September 22, 2000

Agricultural Research Service scientists are teaming up with Abraxis, Inc., of Hatboro, Pa., to help rid fish of offensive flavors known as “off-flavors.”

Researchers with ARS’ Aquatic Animal Health Research Laboratory in Auburn, Ala., signed a two-year Cooperative Research and Development Agreement with the small, minority-owned company.

The thrust of the agreement will be to develop monoclonal antibodies--proteins that lock onto a very specific molecule--that could ultimately be used in a test kit to detect geosmin in fish ponds and drinking water. Geosmin, which is Greek for “smells like dirt,” is one of severalcompounds produced by algal organisms that grow in groundwater and soil and is a major cause of off-flavor. It has an aroma that people typically associate with soil.

Another important algal compound that causes off-flavor, methylisoborneol, will not be studied under this agreement.

Geosmin is produced by blue-green algae blooms--pond scum--in ponds and other water bodies, including sometimes in catfish ponds. Catfish absorb these compounds, resulting in bad or dirty-tasting fish. To ensure bad-tasting fish don’t reach consumers, farmers take their catfish to a processing plant, where a panel of people eat and smell a cooked catfish fillet to check for off-flavor. If the fish fillet tastes bad, the processing plant will not buy the producer’s fish. This results in major losses for producers, costing about $16 million annually.

Currently, there are no effective, environmentally friendly methods to clean up algal blooms in ponds. A geosmin monoclonal antibody could pave the way for more precise water-quality tests and other corrective treatments. It would enable catfish farmers to detect geosmin in water and clean it up before it became a problem.

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

Scientific contact: Richard A. Shelby, ARS Aquatic Animal Health Research Laboratory, Auburn, Ala., phone (334) 887-4526, fax (334) 887-2983, shelbri@vetmed.auburn.edu. Fernando Rubio, Abraxis, Inc., Hatboro, Pa., phone (215) 957-6477, fax (215) 957-6402.