Article courtesy of Russel @ Lake City Coffee
Roasting is truly the process of turning proverbial trash into treasure: the pits of coffee berries become something capable of rendering the perfect brew. As roasting progresses, water is removed from the green bean, causing it to swell and audibly crack. Then, the oils are pulled to the surface, and there is the second crack. By the time the process is complete, the beans are twice their green size and half their green weight.
You could spend hundreds of dollars on a roaster, but our goal here is to give it a try with minimal investment. For this reason, the oven method is the best place to start.
The equipment for roasting in the oven is pretty straightforward:
- an insulated cookie sheet
- a single layer of green beans
- the middle rack of a preheated 500° oven
- a metal colander
- a good exhaust fan—set to high
Place the cookie sheet of beans onto the middle rack and wait for the magic to begin. In 8-10 minutes, the puny greens beans that you’d figure for split pea soup will begin their little happy dance. As the beans’ interior temperatures rise, they will start to swell and eventually begin cracking. It’s also at this point where you’ll get the first sign of smoke and that awesome, hopeful smell of coffee.
Once you have smell and smoke, it is imperative that you watch closely. What happens from here on out, happens quickly! Just when you think the process is over, as there is a short lull of activity, the beans come to life again for what is called the second crack. Here, the oils are being pulled from the bean, rather than simply moisture. The beans will now begin to darken—and will eventually burn. The trick is to stop the process as soon as your desired roast level is achieved. (Below is a description of each roast level.)
Pull the pan out of the oven immediately and carefully pour the beans into a metal colander. Swirling the beans in the colander will help drop the temperature more quickly so that no further roasting occurs. The swirling motion also helps remove the chaff. (Chaff is the thin outer coating of the bean that comes off during the process and should be discarded. Gently blowing on the beans in the colander will help accomplish this.) Allow the beans to cool and rest in the colander for 3-5 hours before grinding—if you can wait that long.
The degree to which the oils are brought out and/or burned off determines the roast level.
- Light Cinnamon – Very light brown, dry, taste resembles toasted grain.
- Cinnamon – Light brown, slightly toasted grain taste, beginnings of an acidic undertone.
- New England – Moderate light brown, slight acidic undertone, typical of lower-end coffee in Eastern US.
- City or Medium – Medium brown, typical of Western US, variations in the bean’s character come through more notably at this profile. This is the beginning of the second crack.
- Full City – Medium dark brown, some surface oil, bittersweet, variations in the bean’s character still coming through.
- Light French – Moderate dark brown, light surface oil, more bittersweet, becoming caramel in flavor, acidity beginning to reduce.
- French – Dark brown, shiny with oil, slightly burned undertone, acidity further reduced, good for espresso.
- Italian or Dark French – Very dark brown, very shiny, burned undertone, acidity nearly gone.
- Spanish – Very dark brown—nearly black—losing oily shine, charcoal undertone, the very second in the process when caramelize becomes carbonization.
Roasted Bean Storage
If you need to store the beans beyond the resting and cooling stage, use an opaque breathable container, or one that is opened daily, such as a canister. Remember that as soon as the oil is brought to the surface of the bean, it begins to go stale. Roast only what you will use within a week’s time.