All coffee beans are roasted before they can be ground and brewed. Roasting coffee cooks out most of the moisture, brings out the oils and gives the beans their familiar dark color. Coffee beans may be roasted at a high or low temperature, for a long or short amount of time. The length and intensity of the roasting process affects the flavor and complexity of the coffee.
How Coffee Beans Are Roasted
Green coffee beans start the roasting process by being lightly toasted. As the temperature slowly increases in the roaster, the coffee beans swell in size, then crack and release most of their moisture. At this point, the sugar in the coffee beans begins to caramelize and the beans begin to release oil.
Roasting may stop after the first crack, or it may continue past this point. As the coffee beans continue to roast, they quickly become darker in color. Very darkly-roasted coffee may undergo a second crack. If roasting continues too long after a second crack, the coffee beans will become bitter.
Common Coffee Roasts
Most coffee roasts are described as “light,” “dark,” “full” or “medium.” These colors refer to the point at which roasting stopped. Light roasts usually stop roasting after the first crack. Medium roasts are allowed to cook a bit longer, while full and dark roasts, such as the popular French roast coffee, continue the cooking process until the coffee beans are very dark.
Light roasts are lightly-colored beans that produce a light-bodied, slightly acidic cup of coffee. Popular light roasts include:
- American roast
- Cinnamon roast
- New England roast.
Medium roasts produce beans that are milk-chocolate brown in color. Medium-roast coffees tend to be sweeter and more full-bodied than light roasts, with a balanced aroma. Common medium roasts include:
- City roast
- Regular roast
- Semi-light roast.
Full roasts continue the roasting process to the second crack. More oils are released in these beans, giving the coffee beans a dark, shiny appearance. Popular full roasts include:
- Full city roast
- High roast
- Viennese roast.
Dark roasts cook well past the second crack, until they begin to smoke. The resulting full-bodied coffee is very dark and shiny, with a pungent aroma and robust, bittersweet flavor. Common dark roasts include:
- Double roast
- Espresso roast
- French roast
- Heavy roast
- Italian roast.