Want a Perfect Cuppa Joe? Roast Your Own Coffee Beans

By: Muriel Vega  | 
green coffee
All coffee beans are green before they are roasted to be brewed into that perfect cup of coffee. Bloomberg/Getty Images

As a coffee enthusiast, you probably have your preferred bean and roast of choice. But what if you wanted to roast your own coffee at home? You'll need to start with green coffee beans. The fruit of the coffee plant has a very hard seed inside — the coffee bean as we know it is typically one half of that seed. The seed must be extracted from the cherry and then stored in burlap bags, as green coffee beans are highly sensitive to moisture and require storage that allows for air circulation.

Green coffee beans are raw seeds that have been processed but not roasted. The outer skin, pulp and inner skin have been removed, and the inner seed has been dried. Unroasted green bean coffee is incredibly bitter as the notes of the bean haven't been released yet through roasting. Think of it as a blank canvas since you can uncover precisely the flavor you want when roasting it.


As with any cooking technique, practice makes perfect. "You can make the same exact green coffee bean taste different by roasting it darker or lighter and in different time frames," says Kevin Langill, owner of Cool Beans Coffee Roasters in Marietta, Georgia, in an email interview. "If you roast a batch of coffee and it doesn't taste very good, try again."

So how do you start roasting your beans and enjoying that fresh cup of coffee every morning? It starts with buying the right beans.

Coffee beans come from the seeds of berries from the Coffea plant. The plant was exported from Africa to countries around the world and coffee plants are now cultivated in over 70 countries, primarily in the equatorial regions of the Americas, Southeast Asia, India and Africa.
Universal History Archive/Getty Images


Buying Green Coffee Beans

Green or unroasted coffee beans are not widely available but can be purchased through certain coffee shops or online through wholesale green coffee companies.

But, all green coffee beans aren't the same. The potential flavors of the green coffee beans will depend on the variety and the conditions they were grown in (think soil, climate, region, etc.). Like any other crop, some green coffee beans may be harder to find as they have a specific harvest season. Once you order the coffee beans of your choice, they will arrive raw and green in color at your door.


What Equipment Do You Need?

Good news: You don't need a ton of equipment to roast your coffee beans. The process is more about trial and error than spending money on fancy equipment. Many people roast their coffee beans in a skillet on the stovetop, and that method gives you a lot of control over the evenness of your roast, though Langill doesn't recommend it as the coffee must be constantly stirred to acheive that even roast.

Instead, he recommends grabbing "an air popcorn popper, a rotisserie on a grill that has a container to hold the beans or a small coffee roaster made specifically for that purpose."


How To Roast Green Coffee Beans

Roasting the beans will trigger the Maillard reaction, a complex chemical reaction that's responsible for the browned caramelization of things — and that makes coffee beans release that robust flavor.

Before you start roasting your beans, Langill recommends a lot of ventilation as the process gets smoky, fast. Before getting started, you'll need to decide if you want to try a light or darker roast first. The lighter the roast, the more likely you are to taste fruity flavors, for example. The darker the roast, the less acidity you get as well as a more toasty, robust roast.


"Coffee is a lot like popcorn when it cooks," Langill says. "It expands in size, loses moisture and weight, becomes easier to chew or grind once cooked, and pops during the cooking process." This is why he recommends using an air popcorn maker to get started and have your beans more evenly cooked. And make sure it's a mild day as extreme temperatures can affect the roast.

green coffee
Coffee beans being roasted outside over a fire in Harar, Ethiopia. You can use the same method at home on your stovetop.
Eric Lafforgue/Art in All of Us/Getty Images


The First Crack

The first part of the process is the drying, which will cook the moisture out of the beans, turning them from green to yellow. Begin constantly stirring your beans with a metal whisk over a medium heat (around 410 to 430 degrees F, or 210 to 218 degrees C). A metal whisk will provide proper air circulation during the stirring process. Remember that you need to stir constantly to achieve an even roast and avoid both burned and raw spots. While watching the beans, you'll begin to see steam and the first crack (pop) at around 6 to 12 minutes. Start watching closely, as this is when the beans go from yellow to brown. Each type of bean will take a different amount of time to roast and every second the bean spends in the popper or on the heat changes its flavor profile. Light to medium roasts normally finish somewhere between the first and second crack, around 12 to 14 minutes. Dark roasts typically finish after the second crack.

Have a metal collander (not plastic — it will melt) ready to pour the beans out; they will keep cooking a bit while they cool down. Toss them until they are no longer hot to the touch. Doing this outside is a good idea, as you will notice the chaff — fine, paper-like flakes — sloughing off the beans, which can be messy in the kitchen.


Langill recommends downloading bean color charts to get familiar with the different shades of roasting. "As you progress, you should track your temperature over time since this has a big impact on flavor," he says.

Take some time to experiment. Roast the same bean in several different ways to test roasting times and see which one is your favorite. Make sure to take notes like a scientist to be able to remember the details of each roast so you can duplicate it.


How To Store Your Roasted Coffee Beans

Now that you've roasted your coffee beans, store them in a cool, dark place inside an airtight container. Make sure to use them within 21 days after roasting because they quickly lose freshness. "Many people aren't aware that coffee is a cooked product and gets stale like one," Langill says.

"You can certainly drink stale coffee, and it won't spoil, but once you've tasted freshly roasted coffee regularly, you should be able to identify stale coffee pretty quickly."