The anaerobic fermentation process is a modern, high-tech technique where coffee cherries or pulped beans are placed in sealed, oxygen-free stainless steel tanks for a controlled period of time. By eliminating oxygen, specific acids and microorganisms flourish under the build-up of CO2 and pressure, allowing for a precise fermentation that develops rare and exotic flavor compounds not found in traditional methods. The result is a highly sophisticated and experimental cup that often features intense, unexpected notes such as cinnamon, dark chocolate, or fermented tropical fruits, making it a favorite for high-end specialty roasters.