Used coffee grounds have been found to contain a surprisingly rich variety of healthful antioxidants, according to new research that suggests they could become a valuable resource for the production of dietary supplements.
A new study published in the American Chemical Society’s Journal of Agricultural and Food Chemistry concludes that the estimated 20 million tons of used grounds that are discarded annually could be repurposed to boost health around the world.
In research funded by the Spanish Ministry of Economy and Competitiveness, lead researcher Maria-Paz de Peña and colleagues from the University of Navarra, Spain, found that filter, plunger, and espresso-type coffeemakers produce the most antioxidants in coffee grounds, while mocha coffeemakers generate the least.
Because filter and espresso coffeemakers are more common in homes and commercial kitchens, the researchers said most grounds are likely to be good sources of antioxidants and other useful substances. Once the beneficial compounds are extracted for use in supplements, they said, the grounds can still be used for fertilizer.
Some spent coffee grounds are now repurposed for commercial use as farm fertilizer, but most end up in trash landfills, De Peña's team noted. She added that coffee itself has long been known to be a rich source of healthful antioxidants, so the findings of the new study make sense.
But the research found levels of antioxidants found in the grounds were four to seven times higher than those found in coffee itself. The main antioxidant compoundes included caffeoylquinic acids and dicaffeoylquinic acids.
Antioxidants are believed to promote good health, by scavenging disease-causing “free radicals” in the body that have been linked to cancer, Alzheimer's, arthritis, and other conditions.