Other home roasting articles on INeedCoffee focus on roasting with electrical roasters, such as the West Bend Poppery or the iRoast 2. You can easily start roasting at home with one of these roasters. But there are other, older methods of home roasting. This article explores using a stovetop popcorn popper, which enables you to roast coffee right on your gas stove. It’s not nearly as easy as roasting with an electrical popcorn popper, but the advantages of this method are that you have 100% control over the roasting profile and you can roast greater quantities at one time.
Is Stovetop Roasting Wrong For You?
Let’s start with a basic truth. Home roasting coffee is easy. That is up till now. Whether you are using a popcorn popper, a Hearthware, Fresh Roast, or even an oven, it really doesn’t take much time before you are making excellent coffee. A big reason for the ease is that the roasting device handles the roasting temperature for you. Even the oven remembers where it should roast once you’ve set the dial. And some roasters even handle the cooling. With stovetop roasting it’s the roasters responsibility to keep the coffee in a temperature profile that will roast the coffee not too fast and not to slow. That requires some practice and constant attention.
During the roast the roaster will need to monitor rising and falling temperatures and make adjustments all while hand cranking the Whirley-Pop. This is rodeo style roasting. Too much heat and the beans will burn, too little and they’ll bake. If you are a hands-off roaster, you can stop reading now. This isn’t for you. The next requirement is excellent ventilation. Roasting coffee produces smoke and the Whirley-Pop can roast 3 times as much as other roasters. This means 3 times the amount of smoke.
The last caveat is the electric stove. I have a gas stove and could not imagine roasting on an electric stovetop. The reason is that during the roasting portion the temps will fluctuate, dropping fast at first and then rising gradually. While this is happening, the roaster is increasing and decreasing the temperature. Electric stovetops do not respond as quickly as gas stoves. Is it possible to use a electric stove? I’m sure it is and I’m sure someone is doing it, but it will add another level of difficulty for the beginner.
Is Stovetop Roasting Right For You?
There are a few things that stovetop roasting can provide that other roasting methods can’t. The first is quantity. Most home coffee roasting machines, including popcorn poppers roast around 2.5 ozs (by weight). The Whirley-Pop can handle 8.5 ozs with no problem. The next thing stovetop roasting provides is complete control of the roast temperature profile. At best other home roasters will only let you control ambient temps, not the roasting temp. With complete control you have more freedom to create different tasting coffee roasts. And the last difference is it uses conduction heat.
The Whirley-Pop can roast 8.5 ozs of coffee at once.
To get started you will need a stovetop roaster with a temperature gauge that goes to 500 F. Without a temperature reading you are roasting blind and will have no idea if you’re burning or baking the beans.
- Stovetop popcorn popper. The most popular brand is the Whirley-Pop (aka Felknor Theatre).
- Gas stove with good ventilation.
- Flashlight or good overhead lighting.
- Pot-holders or oven mitts for opening the popper. This will get hot.
- Metal colanders.
- Green coffee (practice with a cheap uniformed sized bean that can handle darker roasts like Brazil or Colombian).
- An assistant (optional, but helpful).
Before You Roast
- Open the windows, turn on the ventilation, warn your family, move your pets and if necessary disable your smoke detector. You will see smoke!
- Measure out ~ 8.5 ozs of green coffee. Experiment with volume.
- Set the metal colandars either in the kitchen sink or just outside.
Setting the Stove Temperature
The most challenging part to stovetop roasting is being in control of the temperature. Prior to adding the beans, set the roaster on the stove and turn on the flame. Your goal is to get the inside temperature up to 500 F, so make sure the lid is closed. The temperature will fall initially and then as the roast progresses it will climb again. The more you peek inside the roaster, the more heat will escape. Once the temperature has stablized around 500 F, you can pour in the green coffee beans.
Unlike other roasters which push the beans around with fans, you are responsible for moving the beans. To get an even roast, start cranking and don’t stop. If you get tired of cranking, have a friend nearby to switch off with. You don’t want to stop or you’ll burn the coffee. Sometimes I’ll reverse the crank to mix things up. If the crank sticks, give the popper a quick shake (lid closed).
Keep cranking the popper throughout the coffee roast.
Monitor the Temperature
The first thing you’ll notice after pouring the beans into the pre-heated popper is the temperature will start dropping. The 500 F will plummet to between 300 and 350 F. Every stove is different, so the amount of flame you’ll add is something you’ll need to experiment with. The goal is to not the let the temperature drop below 300 F and try to get it close to 400 F. Remember that peeking at the roast releases heat from the popper and will make it more difficult to achieve a steady temperature. It is a good idea to roast by ear. The good news is that unless the stove ventilation is loud, roasting by gas stove is the most quiet method of home roasting. You should easily be able to hear both the 1st and 2nd crack. The bad news is it takes both hands to crank the roaster and one hand to tweak the stove temperature. Having an assistant is helpful.
Finishing the Roast
A typical roast takes between 7 and 9 minutes. Towards the end you’ll hear the start of the the 2nd crack. If the temperature is exceeding 400 F on the roaster, you have the freedom to peek inside to both release some of the heat and check the color and evenness of the roast. Word of warning, don’t peek immediately after you flip the lid or you could burn your eyes on the smoke that will be pouring out. Also be sure to use a pot handler or oven mitt when opening the roaster. If you have an assistant, have them aim a flashlight into the open roaster. The beam of light should cut through the smoke to provide a visual indicator of the roast color.
Whirley-Pop roast in progress.
Although it’s possible to do lighter roasts, it’s going to be a lot easier to go dark. Roasting color with conduction heat seems to even out over time. An additional minute or two can turn a blotchy city roast into a even vienna roast. Once you believe the roast is ready, turn off the burner and quickly carry the popper to your metal colanders. I like having 2 colanders. This allows me to pour the beans from one to another. This both cools the beans and helps remove the chaff. You can also use the spray method for cooling the beans. For more information on cooling roasted coffee read the 2nd and 3rd tip from the article Popper Roasting Tips
Cooling the coffee beans using 2 metal colanders.
Besides being an excellent roasting method for those that wish to tweak the roasting temperature, this is also one of the cheaper volume roasters. For around $30 you can roast more than 1/2 a pound of coffee in under 10 minutes. My final word of advice is this is not the best roasting method for beginners. Someone new to home coffee roasting would be better off starting with a roaster where they can watch the beans go from green to perfection.
UPDATE: Michael T sent in this tip. If you put a cast iron skillet inbetween your pot/Whirley-Pop and electric burner not only does it distribute the heat better but it soaks up and holds heat really well so temperature changes are less of a problem.
In 2007, Michael moved to America's coffee capitol Seattle, Washington. He has visited close to two hundred different coffee places in Seattle, Portland and Vancouver and met many of the top roasters and baristas in the country. Since 2009, Michael has been the Organizer of the Coffee Club of Seattle, which is a Meetup group of over 600 coffee enthusiasts. Besides the social aspect of the group, the Coffee Club of Seattle partners with local coffee professionals for educational events such as coffee cuppings, brewing demonstrations and roasting tours.
Unrelated to coffee, Michael has a personal blog at CriticalMAS.com which covers several topics including fitness, cooking and economics.