Roasting is a heat process that turns coffee into the fragrant, dark brown beans we know and love.
Roasting brings out the aroma and flavor that is locked inside the green coffee beans. Beans are stored green, a state in which they can be kept without loss of quality or taste. A green bean has none of the characteristics of a roasted bean — it’s soft and spongy to the bite and smells grassy.
Roasting causes chemical changes to take place as the beans are rapidly brought to very high temperatures. When they reach the peak of perfection, they are quickly cooled to stop the process. Roasted beans smell like coffee, and weigh less because the moisture has been roasted out. They are crunchy to the bite, ready to be ground and brewed.
Once roasted, however, they should be used as quickly as possible before the fresh roast flavor begins to diminish.
Roasting is both an art and a science
It takes years of training to become an expert roaster with the ability to “read” the beans and make decisions with split-second timing. The difference between perfectly roasted coffee and a ruined batch can be a matter of seconds.
Know your roasts
Most roasters have specialized names for their favored roasts and there is very little industry standardization. This can cause some confusion when you’re buying, but in general, roasts fall into one of four color categories — light, medium, medium-dark and dark.
Many consumers assume that the strong, rich flavor of darker roasts indicates a higher level of caffeine, but the truth is that light roasts actually have a slightly higher concentration.
The perfect roast is a personal choice that is sometimes influenced by national preference or geographic location. Within the four color categories, you are likely to find common roasts as listed below. It’s a good idea to ask before you buy. There can be a world of difference between roasts.
Light brown in color, this roast is generally preferred for milder coffee varieties. There will be no oil on the surface of these beans because they are not roasted long enough for the oils to break through to the surface.
- Light City
- Half City
This roast is medium brown in color with a stronger flavor and a non-oily surface. It’s often referred to as the American roast because it is generally preferred in the United States.
Medium dark roasts
Rich, dark color, this roast has some oil on the surface and with a slight bittersweet aftertaste.
- Full City
This roast produces shiny black beans with an oily surface and a pronounced bitterness. The darker the roast, the less acidity will be found in the coffee beverage. Dark roast coffees run from slightly dark to charred, and the names are often used interchangeably — be sure to check your beans before you buy them!
- New Orleans
Image credit: William M. Murray, Giphy
Inside the Roasting Process – Literally
This fascinating video from Hungarian roaster Laczkó Gábor uses GoPro footage to give you a glimpse into what’s happening inside a commercial coffee roaster.