The most common way to describe coffee roast levels is by the colour of the roasted beans, ranging from light to dark (or extra dark). As coffee beans absorb heat in the roasting process, their colour becomes darker. Oils appear on the surface of the beans at higher temperatures. Because coffee beans vary, colour is not an especially accurate way of judging a roast. But combined with the typical roasting temperature that yields a particular shade of brown, colour is a convenient way to categorize roasting levels.
Medium roasted coffees are medium brown in colour with more body than light roasts. Like the lighter roasts, they have no oil on the bean surfaces. However, medium roasts lack the grainy taste of the light roasts, exhibiting more balanced flavour, aroma, and acidity. Caffeine is somewhat decreased, but there is more caffeine than in darker roasts.
Medium roasts reach internal temperatures between 210°C (410°F) and 220°C (428°F) — between the end of the first crack and just before the beginning of the second crack.