Give up the Roast

Yes, you can roast your own coffee in a popcorn popper. But should you?


Even the most unrefined palate can tell the difference between a good cup of coffee and a bad cup of coffee. I’m well aware that the fine line between the two can easily affect the outlook of an entire day.

After years of enjoying my store-bought coffee in blissful ignorance, I started to wonder what I was really paying for when I threw down three dollars for a cup of hot bean water. I found that even with hand crafted Japanese kettles, meticulously weighed beans, and the never-ending list of “the best” brewing methodologies, we have little control over our own brew. Not even the most well-equipped coffee connoisseur does.

There are innumerable ways in which coffee beans can become compromised well before reaching the cup. The beans can be grown in the wrong climate, picked at the wrong time, cleaned in the wrong manner, fermented at the wrong rate, processed in the wrong way, or mishandled in transport. With the intricacy of farming coffee, it seems to be a miracle that so much coffee can find its way out of the farms and onto the market. Ultimately, the real power lies in the hands of the roasters.

With the ability to either release the minute flavors locked within the grassy, bitter raw seeds or burn it beyond recognition through the careful application of heat, coffee roasters decide the fate of your cup of coffee. Normally, I’d leave this last step to the professionals, but as part of my quest to be the master of my own kitchen, I decided it was time to cut out the middleman and roast my own beans.

Employing all of my scientific and engineering training, I set off to scrape together the minimum amount of base knowledge I would need to get from A to B. I stopped by one of my local go-to coffee spots, the Rival Bros. truck in Philadelphia, to talk to a few coffee devotees who had already made the jump from DIY roasters to cappuccino-slinging coffee experts.


A real roaster at work

Jonathan Adams and Damien Pileggi – the Rival Bros. – work out of the restored Globe Dye Works factory in the Kensington neighborhood of Philadelphia, roasting a variety of beans for distribution and sale through their mobile cafe-truck. Damien, now an expert roaster, started small, working with entry level fluid-bed roasters outfitted with homemade thermocouple probes for roast analysis. As I stood in their roasting shop, I looked around at all of the equipment involved. It served as a reminder of why home roasting faded out in the face of commercialization nearly 100 years ago. All of the temperature control, constant stirring, airflow management, precise cooling, and quality analysis involved in coffee roasting is simply too difficult to compete with at the home level. Still, I was eager to try my hand at it.

For someone looking to break into the home roasting scene, Damien recommended using the FreshRoast, a purpose-build air roaster that was one of his early standbys. Unfortunately, it can only roast a whopping ⅓ of a cup of coffee beans at a time, and costs nearly $200 – a bit of a reach for the uncommitted chef, someone like me. Luckily, the internet did not disappoint in providing me with the perfectly cheap and resourceful solution: using an air popcorn poppers as some sort of gateway appliance to real coffee roasters.

Popcorn poppers are miniature versions of what are known as fluid bed roasters – meaning that the beans float in a fluid-like jet of hot air rising from below. The hot air (reaching upwards of 450°F) flows through the beans with enough force to stir them for even heating, but without so much force that the beans are ejected from the heating area. Cheap, plentiful, and easily modified, these glorified overpowered hairdryers are somehow perfectly designed to roast about two heaping tablespoons of coffee – nearly enough to brew a cup and a half.

For further advice, Damien had also pointed me to Sweet Maria’s, a San Francisco roasting supplier that has become the online center of small scale roasting, home to roasting tips, equipment reviews, and supplies. The site provides how-to guides for roasting coffee using a variety of methods, including the repurposed air-popper technique that I used. My shopping list was brief: a small bag of cheap green coffee from Amazon (the website, not the region) and an old popcorn popper from a thrift store. I even got serious and added a thermometer and timer to my order.

Left: Rival Brothers' professional-grade roasting setup. Right: my hacked popcorn popper.

Left: Rival Brothers’ professional-grade roasting setup. Right: my hacked popcorn popper.

After only a few days of scrounging together my supplies, I was nearly ready to roast. I had my popcorn popper set up next to the sink, with the spout aimed into the basin. My timer and thermometer were on deck, although at this stage of experimental cooking, I hadn’t really decided how I’d implement them. My apartment has neither functioning smoke alarms nor fire extinguishers, so naturally I filled every stockpot I could find with cold water and arranged them strategically around the kitchen.

The first thing that struck me, apart from the noise, was an unexpected aroma. Sharp, pungent, almost acidic, somehow a mixture of freshly-cut and currently-burning grass. I didn’t have much time to worry about the smell, though. I had bigger problems shooting out of the top of my popcorn maker and into my kitchen. Apparently my machine was a little overzealous, and a few beans began flying out of the popcorn shoot. I made the mistake of trying to grab one of these wayward beans and instantly burned a few bean-shaped welts onto my fingers – a mistake that could have been avoided if I had utilized my thermometer.

After about a minute of nervously watching the beans bounce around while clutching the handle of the nearest water-filled stockpot, the coffee beans began to shed their outer layer, which is known as the chaff. One of the advantages of a fluid-bed system is that the chaff is quickly blown away from the beans, although the thin papery films also pose a risk. If they were to fall into the heating element it wouldn’t take much to start a fire.

I pulled the plug after another minute after noticing a few small flames shooting out of the container and quickly dumped the beans into a colander to cool. I surveyed the mess I had made. About half of the beans had launched into the sink basin. As the roasting process advanced and the beans lost weight, it became increasingly difficult to keep them in the bed. Another quarter of the beans were also ejected, but hadn’t landed so conveniently in the sink. I was left with about half of a tablespoon of lightly roasted beans – not bad for a first attempt, I guess. The next steps were clear: build a chimney tall enough to catch escaping beans and press on through the flames to aim for a darker roast.

My highly engineered foil chimney

My highly engineered foil chimney

I engineered my chimney to exacting specifications, or at least I would have if it wasn’t for the convenience of rolling up aluminum foil into a cylinder, folding the top in slightly, and pushing the contraption down into the popcorn chamber. I loaded two tablespoonfuls into the machine and decided that three and a half minutes would be my shutoff point. My manufactured chimney worked. Only a few beans managed to escape to the sink and the chaff was free to flow out of harm’s way. The chimney had the added benefit of obstructing my view, so as far as I’m concerned, there were no fires. A third batch had similar results, and in no time I had enough beans for a sample cup of coffee.

I was eager to taste the fruit of my labors, but I had learned during my research that roasted coffee beans need to degas before brewing. Some bean varieties need days and even weeks for the majority of the carbon dioxide within them to escape. This rest time is vital, so I decided I could stand waiting a few days so my hard work wouldn’t be wasted.

When they were finally read to try, I brought a few servings of beans to my mother’s house, where a fully automatic espresso machine exists to analyze the fruits of my labor. In a matter of minutes, the machine spit out a more enjoyable cup of coffee than I had expected. It was fairly light-bodied, slightly grassy, and just a bit bitter, but certainly better than any fast food, gas station, or diner coffee I’d had recently. A few more cups distributed among family members confirmed that the drink in question was, in fact, coffee, and that it wasn’t terrible.

The final product: most definitely coffee

The final product: most definitely coffee

I also stopped by the Rival Bros. truck for an impartial critique. With a careful visual analysis and a few quick whiffs, my beans were dubbed a valiant first effort, with a surprisingly even roast for a DIY setup – but not without room for improvement.

My entire home coffee setup ran me less than $25: $10 for mail-ordered green coffee, $10 for some assorted tools, a burr grinder acquired via trade (a cheap spice grinder would suffice), and about $2 for the secondhand popcorn popper. With that setup, I can roast about 2 tablespoons of beans in 5 minutes, although the internet warns me that the machine is sure to melt itself if I run more than a few batches at a time.

Of course, buying raw beans is not a trivial expense. Unless you’re purchasing pallets of beans, you won’t be able to benefit from the economy of scale that has allowed commercial roasters to turn profits. And next-level roasters are a much bigger investment – tabletop drum roasters run between $500 and $1000 depending on the features, and generally handle capacities between ½ and 1 cups.

Raw beans in bulk at Rival Bros. headquarters

Raw beans in bulk at Rival Bros. headquarters

My popcorn popper is most likely destined for the deepest, darkest, most inaccessible cabinet in my kitchen. The process was fascinating and certainly enjoyable, but with numerous high quality local and national coffee shops and roasters available to me I do not think that I am an ideal candidate for the home roasting movement. Which raises the question that many had asked me along the way: Why would anyone bother roasting their own coffee?

Looking past the spreadsheets and gadgets, the only reasonable answer I can propose is that DIY coffee roasting is truly an endeavor for those few holdouts trying to resist the commercialization of every corner of their pantry. The same people who grind their own flour, save seeds from their garden year to year, or keep their family’s heirloom vinegar-producing bacteria alive indefinitely might add home-roasting to their list. If you’re looking to save money, look elsewhere. But if you’re looking to get in touch with your food, and aren’t afraid of a little kitchen-hacking or running what is essentially a tabletop, fire-spitting jet engine in your home, go ahead and give coffee roasting a shot.


  1. Bill Harden says:

    Kevin You are amazing! Your writing is also a pleasure to read. Now how about my favorite blue cheese? What fun can we have there.

  2. Ann Harden says:

    Kevin, You are destined for CIA (Culinary Institute of America) You seem to like cooking and experimenting with foods and popcorn makers! You are a terrific writer, so you could also be a writer. There are so many talents you have and it seems you are exploring them. Our customer who came up with the makings of mozzarella as her first project, has gone on to making butter (duh). She also has made kits for making Ricotta and now her latest is making Tofu. She is very successful and she as you just started experimenting with food. Keep up the good work. Love, Grandma

  3. Laurie says:

    Thanks for saving me from ever trying this myself. I will appreciate purchased coffee much more now. Keep up the great investigative culinary work.

  4. David says:

    Very nice article, Kevin. If I ever come across some amazing green beans I’ll send you some just to force you to roast another batch.

    • Kevin (Author) says:

      Thanks David, and you make a good point. Home roasting might be a good way to taste some unique and rare coffee varietals that may not be available at local coffee shops.

  5. carol sacherman says:

    I agree with Laurie! But if your Grandpa could, he would rush there to join you in this great coffee roasting adventure- for sure. He also enjoyed ” do it yourself” with root beer, yogurt, granola-la, and The best F- cake etc. So, I like to think there is an awesome link with him. Beside your maticulous written details, the photos are outstanding . What a treat! Love, the other G.

  6. Helen says:

    My husband started roasting coffee about eight years ago and that’s the only coffee we drink at home (I will admit to cheating with a Starbuck’s Cafe Mocha every now and again).
    A couple of tips if you ever want to try again: One, get an extension cord and roast outside. Once the beans get hot enough to give you a medium or dark roast they will begin pouring clouds of smoke! It makes the entire neighborhood smell amazing – but it doesn’t work well inside.
    Two, hold the popcorn popper and shake it a bit while roasting. That allows all of the chaff to shoot out of the popper and keeps the mini fires from happening. It also allows the beans to roast evenly. Most popcorn poppers don’t have enough air power to move the beans as much as they need to move. If you tilt the popper backwards at the same time it also keeps the beans from flying all over the place.
    Three, roast 1/4 cup to 1/3 cup of beans at a time. It will take a little longer, about 10 minutes depending on the strength of your popper, for each roast but you only have to do one roast for an entire pot of coffee! The extra beans also help keep the scalding projectiles to a minimum.
    Four, roast the beans until you hear them start to crackle. When they’ve start to hear a few random pops, like a dying bowl of rice krispies, then you are just at the level of a medium-dark roast. When your beans sound like rice krispies with freshly poured milk then you are getting to an espresso roast. When you roast the beans to a medium-dark roast or beyond they lose that grassy taste and start developing their own unique flavors. I have had coffee with fruity, chocolatey and even spicy aftertastes!
    Now, my family does like to experiment with making our own treats. We have made our own wine and beer, I make bread every week and I do garden extensively. But most of our experiments peter out after a few successes. The only things we keep doing are the things that are cheaper and taste better than what we buy at the store. We haven’t taken a break from roasting coffee since we started! We have pounds of green beans (did you know you can buy decaf green beans?) that we dip into every weekend. We find the reward is worth far more than the time and effort involved in the making.
    Thank you for your article – it’s always fun to read about adventures in cooking! I thoroughly enjoyed your cheese and yogurt posts. I have tried both and had the same difficulties with mozzarella you experienced. The yogurt worked for us, but once my children decided they didn’t like yogurt anymore I quit making it – I couldn’t go through a whole batch before it became too sour for my taste. All that to say, I enjoy your writing and I will look for more articles from you! Thanks again!

    • Kevin (Author) says:

      Hey Helen,
      Great tips, I’m very impressed at your dedication to home roasting. Have you considered investing in a larger, purpose-built coffee roaster? I’m glad you are enjoying the articles and thanks for the comments!

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