Light roasts are light brown in color, with a light body and no oil on the surface of the beans. Light roasts have a toasted grain taste and pronounced acidity. The origin flavors of the bean are retained to a greater extent than in darker roasted coffees. Light roasts also retain most of the caffeine from the coffee bean.
Light roasted beans generally reach an internal temperature of 180°C – 205°C (356°F – 401°F). At or around 205°C, the beans pop or crack and expand in size. This is known as the “first crack” (for the “second crack,” see below). So a light roast generally means a coffee that has not been roasted beyond the first crack.
Some common roast names within the Light Roast category are Light City, Half City, Cinnamon Roast (roasted to just before first crack), and New England Roast (a popular roast in the northeastern United States, roasted to first crack).
Medium roasted coffees are medium brown in color 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 flavor, 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.
Common roast names within the Medium Roast level include Regular Roast, American Roast (the traditional roast in the eastern United States, roasted to the end of the first crack), City Roast (medium brown, a typical roast throughout the United States), and Breakfast Roast.
Medium-dark roasts have a richer, darker color with some oil beginning to show on the surface of the beans. A medium-dark roast has a heavy body in comparison with the lighter or medium roasts.
The beans are roasted to the beginning or middle of the second crack — about 225°C (437°F) or 230°C (446°F). The flavors and aromas of the roasting process become noticeable, and the taste of the coffee may be somewhat spicy.