Light

Light roasts are light brown in color. Light roasts have a toasted grain taste and can be described as having a grain-like, and higher acidity flavor. The flavors native to the origin of the bean are pronounced and retained in a lighter roast. Lighter roasts also generally have more caffeine, as the caffeine molecule breaks down during a longer roasting process. No oil should be observed on beans that are a light roast.

As beans roast, they heat internally, and at around 300-350°F, the beans expand and a popping sound can be heard. This is called “first crack”. It’s a cool sound when observing a roast and sounds like popcorn popping. A light roast is a coffee that has typically not been roasted beyond the point of first crack. 

There are also categories of roasting, and in Light Roast category are Light City, Half City, Cinnamon Roast (which is roasted to just before first crack), and New England Roast (which is roasted to first crack). 

Medium

Medium roasts are medium brown in color with more mouthfeel or body than light roasts. As with a  light roasts, a medium roasted bean should have no oil on the bean surface. Beans roasted to medium will lose the grainy taste, and will deliver a more balanced flavor and aroma, with a reduction in acidity. These will have less caffeine than a light roast, but still more than a dark roast.

Beans roasted to medium will reach an internal temperature between 410-428°F, and will be complete after first crack, but before “second crack”. Second crack is yet another sound you hear in the roasting process and sounds more like rice krispies popping.

The categories of a Medium Roast include Regular Roast, American Roast (most typical in the eastern US and complete at the end of first crack), City Roast, and Breakfast Roast. 

Medium Dark

Medium dark roasts have an even darker brown color with a slight oil sheen on the bean surface. Medium dark roasts typically have a heavier mouthfeel or body compared to light or medium roasts, but this can depend on the varietal/origin. 

Beans roasted to medium dark are roasted to an internal temperature reaching 437-450°F, and at the beginning or middle of the second crack. At this point, what drinkers identify as a “dark roast flavor” becomes prominent and the coffee takes on a smoky flavor. 

The categories of a medium dark roast include Full City or Vienna roast (roasted to the middle of second crack). These are your typical after dinner coffees that pair magnificently with a rich dessert.