Roasting basics
Roasting coffee has a certain mystique about it. Only highly-trained coffee scientists do that, right? Not really.
Roasting your own coffee is not as complicated as you may think and makes for a great hobby, let alone giving you a great cup of coffee - hopefully.
There are several roasting methods available to us today. Three easy, entry-level options are below. If you are at all interested in learning how to roast coffee, I encourage you to start small (and inexpensive) and work your way up to a more complex machine. There's not much worse than spending hundreds of dollars on a roaster that ends up in a garage sale because you find out too late that roasting is not for you.
One key necessity for roasting is finding a provider of green (unroasted) coffee beans. You can see a few options below.
Popcorn popper
Yes, you can definitely roast coffee in a popcorn air-popper. I started out roasting this way and made some really great coffee. They are inexpensive and a great way to test the waters to see if roasting is something that you really want to do.
Because they are not designed for coffee beans, there is a little babysitting needed during the roasting process, but overall, they actually do a pretty good job. You can't beat it for the money!
Air roaster
Similar to an air-popper, these small coffee roasters use hot air to roast the beans. It is much easier to control the temperature and length of roast with these machines and they produce a great-tasting bean.
These machines are widely available for $200-$300 and are a great starting place for your roasting obsession.
Drum roaster
Coffee beans are packed into a cylinder-shaped compartment that rests sideways. The drum spins in a circle while gas, electricity, or an open flame heats the beans from underneath. The drum roaster evenly distributes this heat throughout the beans as they roast. The constant rotation of the beans ensures that each bean is exposed to the heat at the same rate and intensity resulting in an evenly roasted batch of beans.
Roasting Timing
Knowing how long to roast your beans and when to pull them from the heat is critical to getting a roast that meets your personal taste.
When coffee is roasted, it undergoes a number of chemical changes that can be distinguished by various sensory cues. For specialty coffee roasters, it’s important to pay close attention to these cues in order to achieve the desired flavor and aroma of their coffee.
Two of the most distinctive indicators of how beans are changing during the roast are the temperature thresholds known as the first and second cracks. The two “cracks” are named for their audible popping sound, and typically occur at 196°C and 224°C. To this day, they are used by roasters to reach a target roast profile and develop flavors in the right way.
First crack
At around 196°C, the beans will emit a cracking sound not unlike the sound of corn kernels popping. This is called “first crack”.
At this stage, the beans enter an exothermic reaction, releasing built-up energy, steam, and carbon dioxide (CO2) from their core. They spontaneously expand and expel chaff, and start to give off smoke. During this time, the bean surface temperatures decrease for a brief period as water rapidly escapes the beans – a phenomenon known as the “endothermic flash”.
Many roasters finish their roast shortly after the first crack, as this brings out the nice, bright, natural characteristics of the coffee. However, sometimes, very light roasted coffee might taste sour. Whether you should stop soon after the first crack or continue for a while longer largely depends on preference.
Second crack
During the first crack stage, the cellulose structure of the bean continues to break down and becomes more brittle, paving the way for a second crack. During this time the beans will also start developing more sweetness.
When a second crack occurs (typically around 224°C) the oils within the coffee beans start to migrate to the surface. The roasting smoke also becomes darker and more pungent. This is characteristic of dark roast profiles.
It’s important to carefully monitor this stage of the roast as the character of the beans begins changing at a rapid rate; if left for too long, they may even ignite.
Roasting too deep into the second crack will mask even the stronger and more distinctive flavors of your beans. Instead, they will start to taste burnt and smoky, with muted acidity. Later after a second crack, they can even start to taste like charcoal as the body of the coffee decreases.
The point at which you choose to end your roast will depend on the roast profile you are trying to achieve. Darker roasts are sweeter and have a more traditional “roasty” flavor, while lighter roasts are more acidic and often sought-after among third-wave coffee consumers.
I personally prefer to roast until about 1/3 of the beans reach the second crack. I find it gives the rich flavor I want without the "burnt" undertone. Experiment with the timing of your roasting and find the perfect roasting method and timing for you.
*portions adapted from "Coffee Roasting Basics: A Guide To First & Second Crack" www.mtpak.coffee
Unroasted bean providers
Here are a few unroasted bean vendors to check out. I have found Sweet Maria's to have great beans at an affordable price, but the others also have a good reputation.
Sweet Maria's
www.sweetmarias.com
Genuine Origin Coffee
www.genuineorigin.com
Burman Coffee Traders
www.burmancoffee.com