This only works with certain types of popcorn poppers; what you need is the type where the hot air is forced into the popping chamber through a series of vents around the sides at the bottom of the chamber, creating a vortex effect. This makes the popcorn swirl around as it gets heated up, and if you're roasting coffee it swirls the chaff upward and out of the popper into your chaff-collecting bowl. DO NOT attempt to use a popper where the hot air enters the popping chamber through a mesh covered orrifice on the bottom! This design could ignite the chaff.
How to do it:
- Set up the popper in a ventilated place near a kitchen exhaust fan or window, if possible. It's nice to have strong overhead light so you can look down into the popper chamber to accurately judge the roast as it progresses. Have all your supplies within reach.
- Put the same amount of coffee in the popper that the manufacturer recommends for popcorn.
- Put the plastic hood (including butter dish) in place, and a large bowl under the chute. You could put the popper by the sink so it blows chaff right into the basin. Turn the thing on.
- Watch for fragrant smoke and the "first crack" of the beans in about 3 minutes. Wait another minute, then start to monitor beans closely for desired roast color by lifting out butter dish and looking into popping chamber, or, better yet, by smelling the smoke and listening to the crackling.
- Total time for a lighter roast should be around 4 minutes, full city roast around 5, and darker roasts closer to 6.5 minutes. Roasts develop quickly, so be vigilant.
- You want to pour the beans out of the popper when they are a tad lighter than the color you desire, since roasting continues until beans are cool.
- Agitate beans in metal colander with a big spoon or toss between 2 colanders until they are warm to your touch. You may need oven mitts for this.
- Coffee should be stored out of direct light (and not in a fridge or freezer) in an airtight glass jar, but with a fresh roast, wait 12 hours to seal the jar tightly; it needs to vent off C02.