Some of our very favorite foods and beverages are fermented: chocolate, wine, beer, bread, sauerkraut, kimchi, and… coffee? Well, yes and no: While fermentation is involved in the production of a majority of the world’s coffee, coffee itself isn’t a fermented beverage like spirits or kombucha are. Instead, when we talk about coffee fermentation, we’re referring to what the coffee fruit undergoes between the time that the cherries are harvested and the seeds are fully dried and ready for export.
The word “fermentation” describes the process of metabolization of sugars and other compounds by microorganisms like yeasts and bacteria, which will consume those compounds and convert them into fuel for their own use, leaving behind useful by-products like ethanol and different acids. Those converted compounds are absorbed into the cellular structure of the seed and, when heat is applied to those seeds in the roaster, the compounds will be what transform into the flavors we love in coffee: Complex tastes, fruity acids, and other good, or at least interesting, stuff.