Your Coffee’s Flavor Might Be Decided by a Microbe You’ve Never Met

Long before a coffee bean ever hits a roaster, it goes through a wet, messy, microbial process that almost no one drinking the cup ever thinks about. Freshly picked coffee cherries are wrapped in a sticky, sugary layer called mucilage, and to get clean green beans out, processors let microbes eat that layer away. This is coffee fermentation, and for most of history it has been a spontaneous free-for-all: whatever yeasts and bacteria happen to be drifting around the farm show up and do the work.