We’ve all heard how coffee is good for you. Recent studies have linked drinking coffee with a lower risk for developing many conditions, including type 2 diabetes, Alzheimer’s disease and Parkinson’s disease. It also has more healthful antioxidants than vegetables or fruit combined.
But surprisingly, a lot of antioxidants remain in the gunk in the filter when you brew that cup of joe, say researchers.
Of course, people around the world drink millions of cups of coffee every day. That generates an estimated 20 million tons of used grounds annually. Some spent coffee grounds are actually used commercially as farm fertilizer or in homes as plant food or insect repellant. But most used grounds end up in the trash.
Maria-Paz de Peña's team knew that coffee contained lots of antioxidants, and they wondered how much of those healthful compounds remained in used grounds. Specifically, which coffee-making method would leave the most antioxidants in the grounds?
In their report in the Journal of Agricultural and Food Chemistry, they found that filter, plunger and espresso-type coffeemakers left more antioxidants in coffee grounds, while mocha coffeemakers left the least. Because filter and espresso coffeemakers are more common in homes and commercial kitchens, the authors report that most grounds are likely to be good sources of antioxidants and other useful substances. They note that after these compounds are extracted, the grounds can still be used for fertilizer.