The study, which researchers say is the first to link bean color to antioxidant activity, is scheduled to appear in the Dec. 31 issue of the Journal of Agricultural and Food Chemistry, a peer-reviewed journal of the American Chemical Society, the world's largest scientific society.
The researchers tested the antioxidant activity of flavonoids plant pigments found in the skin of 12 common varieties of dry beans. Antioxidants destroy free radicals, which are highly active chemicals whose excess has been linked to heart disease, cancer and aging.
Black beans came out on top, having more antioxidant activity, gram for gram, than other beans, followed by red, brown, yellow and white beans, in that order. In general, darker colored seed coats were associated with higher levels of flavonoids, and therefore higher antioxidant activity, says lead investigator Clifford W. Beninger, Ph.D., a research associate at the University of Guelph in Ontario, Canada.
"Black beans are really loaded with antioxidant compounds. We didn't know they were that potent until now," says Beninger, formerly a researcher with the USDA's Sugarbeet and Bean Research Unit, located at Michigan State University in East Lansing, where he worked on the project under the leadership of co-author George L. Hosfield, Ph.D., a geneticist who recently retired from the USDA.
The study found that one class of compounds in particular, anthocyanins, were the most active antioxidants in the beans. Based on a previously pu
Contact: Allison Byrum
American Chemical Society