Besides the obvious taste and color differences, the roasting process is what truly sets light, medium, and dark roasts apart. Here’s how it works:
Light roast coffee beans are lightly roasted, meaning they’re roasted for the shortest amount of time. To make a light roast coffee, raw green coffee beans are placed in the roaster at 350°F – 400°F and finish roasting the moment they reach an internal temperature of approximately 385ºF. At this temperature, the beans make their first popping sound or, as it’s called in coffee lingo, the “first crack.” Beans removed from the roaster immediately after the first crack are light roast beans. Light roast beans are also referred to as Light City or Half City.
For a medium roast coffee, beans remain in the roaster for a longer period of time, until an internal temperature of approximately 420ºF is achieved. Instead of waiting for a second crack, the beans are removed anywhere from just after the first crack or moments before the second crack. Medium roasts coffees also go by the names American Roast, Breakfast Roast, Regular Roast, and City Roast.
The difference between dark roast coffee and its counterparts is the most dramatic. The beans are roasted the longest to approximately 440ºF – just until the second crack or shortly thereafter. Dark roast beans are also known as Full-City Roast, Vienna Roast, French Roast, and Italian Roast.
When drinking a dark roast, you’re almost exclusively tasting notes from the roast. The brightness of light roasts is replaced with body in dark roasts. Because the original coffee’s qualities are mostly lost at this roast level, it’s difficult to pick out the characteristics of a specific coffee’s origin or lot. Historically, dark roasts have been popular in Europe, giving rise to terms such as Continental, Italian, French, and Spanish roasts. Espresso roasts are also usually dark roasts, which is partly why espresso can stand up to lots of milk and sugar. Roast level is largely a personal preference, as each level produces different qualities in the coffee. Knowing whether you prefer light, medium or dark roasts, though, can help you identify new coffees that you might like.