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By Mark Frauenfelder
Relaxing in a coffee house with a professionally made cup of espresso or cappuccino is one of life’s simple pleasures, but I also enjoy making my own coffee drinks at home. I buy whole beans online and grind them in a coffee grinder. I’m a pretty good home barista, if I do so say myself.
The one coffee-making activity I’ve always avoided, though, was roasting coffee. I assumed that coffee roasting required large, expensive machinery and considerable training. But a few weeks ago, I heard about a way to roast coffee using a hot air popcorn popper. I gave it a try and found out it was fun and very easy. It takes less than 15 minutes to roast a small batch.
Home roasting is not only fun, it’s economical. Green beans cost about half as much as roasted beans, and they stay fresh up to a year. (Roasted beans lose flavor in a matter of days.)
Here’s how to roast your first batch.
For a PDF of this tutorial, visit the technique page on Make: Projects.


Green coffee beans, I get mine online from Sweet Maria’s


Hot air popcorn popper, the best has a chamber with a flat bottom and vents around the side, such as the West Bend 82416 Air Crazy popper, $25
Metal colander
Large wooden spoon, optional
Small glass jar with lid
Timer A timer will let you know when to start listening for the sound of the “first crack” and “second crack” described below. I use the stopwatch app on my iPhone.


Step 1: Set up your tools and materials in a well-ventilated, well-lighted area. I roast in the back yard, not only because the roasting process creates a strong smell that would linger indoors, but also because the beans shed a lot of chaff that floats around and settles everywhere.
Step 2: Put 1/2 cup of green coffee beans into the popper and turn it on. If the beans spin quickly in the chamber, add more beans, a bit at a time, until the beans spin very slowly. Don’t add too many beans or you will end up with an uneven roast.
As the beans begin to roast, keep your eyes and ears open for three telltale signals:
A. The first thing you’ll notice is the production of chaff, which is lightweight, amber-colored fluff that floats out of the popper.
B. The beans will start turning faster as the water in them evaporates.
C. Sometime between the 2- and 3-minute mark you should hear the “first crack.” It sounds like a dry twig snapping.
All three things are signs that the process is moving in the right direction.
Step 3: If you like very light roast, you can stop anytime after the first crack. Most people like a darker roast, though. (The lighter the roast, the more you can taste the coffee; the darker the roast, the more you can taste the roastiness.) Keep listening for the “second crack,” which is quieter than the first crack. I like to keep roasting for a couple of minutes beyond the second crack, which gives me a dark roast. If you go much longer, your coffee starts to get into “Charbucks” territory.
Step 4: Pour the beans into the colander, taking care not to burn your hands on the popcorn popper, which is pretty hot. Stir the beans with a spoon or simply hold the colander and swirl the beans around. This releases the heat from the beans, quickly halting the internal roasting that’s going on. Let the beans cool down to room temperature.
Step 5: Transfer the roasted beans into a glass jar. The smaller the jar the better, because you don’t want a lot of air mixing with the beans (it oxidizes them and kills the flavor). Don’t screw the lid on too tightly, because the beans should be able to “outgas” overnight. After that, you can screw down the lid. The next day, open the lid, put your nose over the jar, and inhale deeply. The aroma is incredible. Now, prepare your coffee as usual and enjoy your first home-roasted cup!
About the Author:

Mark Frauenfelder is editor-in-chief of MAKE.

10 Responses to How-To: Roast Coffee with a Popcorn Popper

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  1. completely awesome. thank you for taking the mystery out of this very smelly process lol…

  2. I’ve been using the same popper for the last 10 years. Here’s a couple of things:
    – I cut the top and bottom out of an old tin can and stuck it in the top as a chimney. This helps keep the beans in, as they ‘plump up’ quite a bit during roasting, and lose ~20% of their weight (water driven off) so they fly around more toward the end of the roast.
    – There’s lots of smoke and chaff. so it’s an outdoor job, unless you take the filters out of your (externally vented) range-hood, and sit the popper about 1″ below the extractor fan. Afterwards, you can hold the colander directly against the fan housing, and suction-cool the beans in less than a minute. Just don’t – ya know – feed your fingers through the fan blades..
    – the popcorn makes needs to be full enough to retain heat in the beans, but not so full that the beans can’t move. Until first crack, I shake the popper gently so that beans don’t get caught and burn, and to help the chaff blow away.
    – I buy beans once a year – about 30lb at a time. I go in with a group of friends and we buy a couple of 120lb sacks of different varieties, and split it up among ourselves. It’s about 1/4 the cost of buying roasted beans, and I never run out.
    – having used a popcorn maker to roast coffee, you probably won’t want to use it for popcorn again :/
    – my popcorn maker can do enough coffee for three days (two people, one double shot each == 2people x 30g x 3days). Roasting needs to be built into your routine somehow or it won’t get done. Recently I found a second identical popper for a couple of bucks at a charity shop, so I can tandem roast. Feel the power!
    – home-roasting coffee has found its way into my life, and I recommend it without reservation.

  3. In the few months I’ve been roasting with an air popper, I’ve never had any smoke problems. I roast in my kitchen, on a table located fairly close to a window. I put a box fan in the window, pointing outside, and that takes care of any smoke/steam that comes from the roasting beans.

  4. I highly recommend getting a few of those self-venting reusable coffee bags. Once you’ve cooled off the beans, just throw them in there for the “outgassing” step. Foolproof and the perfect storage.
    It’s also a good idea to do your roasting a few days prior to your need to use them. I don’t remember the reasoning, but I remember reading that you should wait 3-5 days to get the best flavor out of your roast.

  5. No one mentioned the toasters burning out. A friend of mine had a stack of burned out toasters, but maybe he just makes a lot of coffee.
    Has anyone found a toaster that will hold up to a coffee addicts, usage?

  6. I highly recommend getting a few of those self-venting reusable coffee bags. Once you’ve cooled off the beans, just throw them in there for the “outgassing” step. Foolproof and the perfect storage.
    It’s also a good idea to do your roasting a few days prior to your need to use them. I don’t remember the reasoning, but I remember reading that you should wait 3-5 days to get the best flavor out of your roast.

  7. Spiny Norman on said:

    Been doing this for years. 2 tips:
    Fist crack sounds more like a pop, second crack sounds like a snap. That helps to tell the late first cracking beans from early second crack.
    Roasing time depends on ambient temperature so don’t just go by the clock.
    The aroma that lingers from roasting indoors can be kind of nice.

  8. We like French Roast. does anyone know what kind of beans to buy or how to roast French Roast? Thanks

  9. I use my Wok (cast iron, HEAVY) but I like this idea. ‘ll try it out (never could stand popcorn anyway) and compare which gives me MY flavour

  10. I tried it at home, a perfect cup! thx

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