What exactly is in your cup of coffee? Besides coffee grounds and water, of course, there may be corn, potato flour, soybeans, brown sugar, and other fillers. Coffee ranks alongside olive oil, honey, and milk as one of the most frequently adulterated foods.

But researchers in Brazil, one of the world’s top coffee suppliers, have developed a simpler, less error-prone test that can sniff out filler materials by their chemical fingerprints. The test uses liquid chromatography, a process that separates individual components from a mixture and identifies each one according to its chemical content. Comparing carbohydrate profiles, it’s simple to spot adulterants like grains from pure coffee.