Several factors substantially affect the flavor of home-brewed coffee; the most important is the roast. The lighter the roast of the bean, the weaker the flavor and, surprisingly, it has the more caffeine. Most canned coffee are light roasted. Dark roasts, such as Italian and French coffee varieties are used for espresso. A medium roast, such as Danish coffee or Vienna roast, is a blend of dark and light-roasted beans.
Full Article: The Perfect Personal Coffee Blend