Gallery: Turn a Cheap Popcorn Popper Into a DIY Coffee Roaster
01Photo: Ariel Zambelich/WIRED
Home roasting is the pinnacle of coffee geekdom. You get to pick exactly where your coffee comes from, choose the roast level, and enjoy it fresh, knowing not only what day it was roasted, be also what time. For beginners, the hand-cranked, stovetop Whirley Pop popcorn maker can be hacked into a bare-bones coffee roaster. For budding home roasters, this cheap mod is an excellent place to start. You can make the roaster as precise or as low-key as you want — either way, it has the potential to make some great coffee. A huge array of literature has already been generated on the subject of Whirley Pop hacking. I've read about folks welding a drill bit to the hand crank, or creating a shop-vac-powered rapid cooling system. I opted for one of the simplest "Frankenroaster" hacks: punching a hole in the lid of the Whirley Pop to install a digital thermometer. As easy as the hardware modification is, keeping track of the roast while you're underway takes diligence. At the very least, you should monitor your progress and log the roast as you go using a pen and paper. Daredevils will tell you to just wing it, but if you're just starting out, logging is necessary for identifying and correcting mistakes. There are also a couple of apps made for monitoring beans. If you have an iPad running iOS 7 or later, download the $10 [Roastmaster app](https://itunes.apple.com/us/app/roastmaster/id375526217) to manually input your temperature as your roast goes along. And at $49 for the most basic monthly subscription, [RoastLog](http://roastlog.com/tour/overview/) gives you a live feed and tracks your roast online. I used a timer and thermometer to keep track of the roast. To prepare, I read [Sweet Maria's roasting guide](http://www.sweetmarias.com/instructions.php), studied Michael Sivetz's chapter on roasting in [*Coffee Technology*](http://babel.hathitrust.org/cgi/pt?id=mdp.39015002932617;view=1up;seq=5), and asked for advice from some roasting professionals. To see how the DIY roaster performs when compared to more expensive home-roaster appliances, [read our coffee roaster review roundup](http://stag-komodo.wired.com/reviews/2013/12/coffee-roasters-gallery/). __What you'll need:__ - 6-Quart [Whirley Pop](http://www.sweetmarias.com/sweetmarias/coffee-roasters/stovetop-roasters/whirleypop.html), $27 - [Digital Thermocouple](http://www.sweetmarias.com/sweetmarias/coffee-roasters/roasting-supplies/digital-thermometer-with-thermocouple.html), $30 - Timer - A good scale that can measure grams. [I recommend this one](http://www.americanweigh.com/product_info.php?cPath=102&products_id=338) ($90), though cheaper options are fine - About 8 ounces (226g) of [high-quality green beans](http://www.sweetmarias.com/coffee/central-america/guatemala) - Hammer - Nail - Wood - Stovetop - Metal colander (or two) - Safety glasses (just in case)
02Photo: Ariel Zambelich/WIRED
Step One: Prep the Roaster -------------------------- Use the piece of wood to support the Whirley Pop lid and hit the nail through the thin metal. Make sure the hole is big enough to comfortably push the probe through. Insert the probe. Don't force it — remember, you have to be able to take it out so you can easily clean and store the Whirley Pop after. 
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Step Two: Roast 'Em ------------------- Start by preheating the roaster. Set the Whirley Pop on the stove and heat it to around 200°F. You want the interior surface and the air inside to be pre-heated, but not too hot. The insides of the beans need to be roasted slowly, but if the pan is too hot, the outside will char before the inside has a chance to heat up. Add 226 grams of coffee and start your timer. The timer is important because you can get a good idea of your coffee's development by what smells are wafting from your Whirley Pop at what time. The Whirley Pop doesn't have a window to watch the beans, though you can lift the lid every once in a while. But remember, every time you lift the lid, you are letting out heat, so don't get too peek-happy. After __2 or 3 minutes__, you will begin smelling the odor of hot alfalfa as the beans start drying out. At around __5 or 6 minutes__, toasty smells dominate before more sweet aromas waft out. If you smell smoke, immediately take your roast off the stove. It's probably too hot, and you're scorching the outside of your beans. Smoke is a common by-product of roasting, but you shouldn't see it until the very end. Constantly crank that Whirley Pop. Don't stop! Agitation is very important for an even roast. Listen for the "first crack" at (hopefully) __8 to 12 minutes__ in. When the temperature on your thermometer reads around 400°F, you'll start to hear your coffee pop. Some beans pop early while others take longer. It should finish up within a couple minutes of starting. After the cracks dissipate, your coffee is consumable. But how dark do you like it? If you want your coffee to have a more light and bright acidity, pull it now. If you like a more full-bodied cup, keep it in for a wee bit longer. Check the color of your coffee a lot at this point. This is the Goldilocks moment of the roast. You have a very short window between too light, too dark, and just right. If you like French Roast coffee, well done steak, and corner-piece brownies, you might want to take your coffee to the second crack. Second crack is much quieter than the first crack and usually happens around 450°F. I'm not going to get too much into the politics of roast level, but I will chime in and say that if you're buying pricey beans like Jamaican Blue Mountain or Panama Geisha, please do not roast it too dark. Now, there's nothing wrong with dark roasted coffee, but roasting El Injerto's Mocca to charcoal-status roast level is like using a 50-year-old scotch to make a whiskey sour. Roast light on the good stuff to bring out the natural flavors you're paying extra for.
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Step Three: Cool Off -------------------- Remove your beans and let them cool in a metal colander. If you want to be hands-on here, you can use this time to agitate the beans and speed up the cooling process. If beans are left hot for too long, the delicious soluble oils can evaporate instead of staying in the bean and eventually making it to your cup.
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Step Four: Prep Your Coffee For Drinking ---------------------------------------- First, get rid of the chaff — the thin, papery hull of the beans that flakes off under heat. If you want, you can collect this roasting byproduct for use as mulch or chicken coop litter. The easiest way to get rid of it is to toss the coffee between two containers and let the chaff fly away. Other methods include using a vacuum or fan. Next, let the coffee breathe. The other major byproduct of coffee roasting is carbon dioxide, so let your coffee "off-gas" for at least 12 hours before storing it in an air-tight container. The gas is slowly released from the beans, and packing it into a sealed container right away will generate enough pressure over a few hours to cause an explosion. After off-gassing, it's ready to brew! Coffee usually tastes best between 4 and 14 days after the roast, though that window can be shorter or longer depending on the coffee and your preferred brew method.
