Why a long-lost coffee bean rivals the best

When Aaron Davis, a botanist at the Royal Botanic Gardens, Kew, first tried stenophylla coffee, his expectations were low. But the first sip took him by surprise: “I was like, oh my goodness, that is just unbelievable,” he says. The coffee was sweet, with notes of chocolate and caramel and a hint of jasmine. Stenophylla had been lost to consumers since the early 20th century and only recently rediscovered by Davis and his colleagues in the rain forests of Sierra Leone. To Davis and a panel of judges, it tasted like Rwandan Bourbon—a superior variety of Arabica. From a chemical perspective, that similarity was puzzling. Coffea stenophylla is a separate species from both Coffea arabica and Coffea canephora (robusta). “It occurs in a completely different environment. It’s got black fruits instead of red fruits,” Davis says. “If you’re a coffee nut, it’s kind of mind blowing.” To find out why it tastes so much like Arabica, Davis and his colleagues set out to research stenophylla’s chemistry. The results were published in March: despite being a different species, stenophylla has a similar molecular profile to Arabica’s. Both have comparable levels of bitter and even fruity compounds that make Arabica taste great. But, as Davis and his colleagues found out, stenophylla also has some unique qualities—for example, in addition to caffeine, it contains the rare stimulant theacrine. The study’s results are “really exciting,” says Elizabeth Tomasino, an enologist and coffee researcher at Oregon State University, who was not involved in the study.