ROASTING

Roasting coffee beans develops their full potential for flavor and aroma. It’s simple in theory: Carefully heating coffee beans can cause a series of reactions that change the chemical properties of their flavor components in desirable ways. In practice, it requires a lot of skill.

As coffee beans are roasted, they go through key steps wherein their moisture evaporates, their volume increases, their sugars caramelize, they exhaust gas, they crack open, and so on. Since every varietal is different, the roastmaster must learn how each responds to roasting and devise individual roasting profiles. These profiles dictate temperature variations over time and can be programmed into computers that control the roaster itself, but true craft roasters also rely on the sights, sounds, and smells of roasting coffee to determine when each batch is perfected.

Once the beans are roasted to the desired level, they’re quickly cooled to stop the process. Freshly roasted beans continue to release carbon dioxide afterwards, so they’re usually allowed to rest or packaged in bags with one-way valves that let the exhaust out without letting air in. Good roastmasters cup their roasted coffees for quality control, ensuring consistency between batches.