How to Home Roast Coffee

This tutorial will show you how to roast coffee at home. Coffee beans lose about 30% of their volume and weight during a roast. So, the 15 oz of unroasted coffee in this recipe yields about 10 oz of roasted coffee. Preheat to cooldown is 25-30 minutes.

Ingredients

15 oz of green coffee beans.

Let's say:

Tools

In order of use:

WARNING

  1. Roasting coffee produces a thick, smoke-like steam that leaves the roast area smelling like coffee everywhere for a short time. It won't set off your smoke alarm, but it will be noticeable to surrounding inhabitants.
  2. During the roast, coffee releases a significant amount of carbon dioxide (CO2), which is the main gas we breathe out. Avoid inhaling this gas by not sticking your head directly over the cast iron when you roast.
  3. Roast coffee in a highly ventilated area.
  4. Always use caution and oven mitts or other gloved protection when handling the hot cast iron while initiating the cooling process. It's hot!
  5. Never leave the cast iron unattended during a roast. Prepare to be chained to the process for over 30 minutes.
  6. A smaller batch will produce less steam, will require a smaller, lift-friendly, cast iron chamber, and result in a faster cooling process, which is very important. For less overall fuss, you can use a 3-quart, high-sided, cast iron saucepan with 9 oz of green coffee. Begin a roast with this setup at around 215 degrees. Use the sight/sound/smell signals described below to judge timing and preferred roast level.

How to do it:

Keep in mind the the sight/sound/smell signals detailed below.

In order: With pre-weighed coffee ready to go, turn on fan(s) to push air outside, stick an oven thermometer in a 5-quart cast iron Dutch oven, set the flame to high, start timer one, and preheat to 250-270 degrees F. This should take about 7-8 minutes.

At desired temperature, safely remove thermometer with an oven mitt, start timer two, and throw in the green beans. Whisk at a moderate pace in circles and center-agitating sweeps for the entire roast. While circling, ensure that all beans get equal contact with the metal for a more even roast.

The beans begin to yellow, steam, and give off a grassy smell at 3-4 minutes. By the 9th minute, most of those buggers are slightly brown and are producing a crackling sound. This is called, you guessed it, the "first crack." This represents the beginning of the palatable spectrum of roast levels, but we're not going to stop there.

The longer the roast, the browner they get, duh, and the resulting steam becomes thicker. The crackling dies down, only to return in the more crackly and less intermittently poppy sounding "second crack," which, along with a darker color bean, is a sign that you have reached the dark roast sub-spectrum.

I usually pull the coffee from the stove at 14-15 minutes, near the middle of the second crack. I judge the roast's finality on the activity of the crackling and the color of the beans.

By this time, your kitchen will be filled with thick, smoky steam that smells like burnt loaves of coffee flavored bread. Now, ideally, you will cool the beans in 3 minutes. You can dump the beans in a wire colander and whisk them around over a sink. This cooling method will take at least 6 minutes. I use an old vacuum cleaner with its hose poked into the lower side of a 5-gallon bucket. The bucket is crowned with an extra-large stainless steal mixing bowl with holes drilled to allow airflow to suck away the heat of the beans toward the bottom of the bucket and into the vacuum. The contraption is made airtight with a fair amount of overlapping packing tape where needed. This cools beans in about 3 minutes. Both of these methods not only cool the beans, but get rid of bitter chaff produced by the beans' silverskin, or outer layer.

Directly after the roast, there's a three-hour degassing period where the beans release a lot of CO2. Let the beans "air out" in a minimally tightened Mason jar. Seal the Mason jar after three hours. For the next few days, quickly "burp" the gathered CO2 once a day. Alternatively, you can buy heat-sealable, one-way valve bags in bulk (you have probably seen the little plastic discs on foil bags that prevent O2 from entering, while allowing CO2 to escape). I use my wife's hair iron to make the seal. Press for 5-10 seconds with no goo or mess on the iron. One-way valve bags allow beans to stay fresh for a long time, so they are good for storing and gifting beans.

In my opinion, coffee is best enjoyed 4-6 days after the roast. This allows flavor to develop and oil to make its way through the porous inner structure to the surface of the bean. You can let beans stew and produce lots more oil for a richer taste, but they will lose some of their fresh-roasted brightness.

I buy fair trade/organic green beans online from Dean's Beans. Call me what you will, I like fair trade because coffee growers make an average of 7% of the total profit of the coffee industry, while coffee is one of the most profitable industries in the world. Fair trade is not always more expensive than conventionally grown coffees. The distinction is that the price of fair trade coffee is set, so that farmers who provide us with our daily coffee can continue to grow the world's best coffee without wondering if they can afford to send their children to school next year. I prefer to splurge for organic because many sources peg conventionally grown coffee at the top of the pesticides usage list. The reason for the abundance of pesticides is the practice of clearcutting trees (often crops, like banana and other fruits) to grow coffee plants in full sun. This spoils ecological diversity at the expense of our health.

Including the price of beans, bean weight loss, shipping fees, and cost of gas, I pay about $8 per pound compared to premium retail coffee beans that go for around $12 per pound. I promise you, even when the flavor is not absolutely divine (which is the norm, after some practice), home roasts tower over the best commercial roasts. Think: fresh whipped cream, real apple pie, homemade bread...

Enjoy!

*All of my roasting is done on a gas range. If this recipe doesn't work for any non-safety-related reason, you can modify the recipe, or try roasting with: a single, propane-fed burner (outdoors), a modified, gas BBQ grill (outdoors, 5 lb batch), a popcorn popper (outdoors) or a retail, plug-in air roaster. You can also modify the colander cooling method with a fan (outdoors). Just search it.