How to Roast Coffee in a Popcorn Popper

Three Methods:PreparationRoastingAfter Roasting

While you can easily buy home coffee roasters on the Internet, the prices can put a strain on your wallet. In addition, using home roasters tends to be something of a mystery. But there's another way of roasting coffee at home--using a cheap hot-air popper instead!

Method 1
Preparation

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    Find the right popcorn popper. The most important thing to look for in your popper is a unit that feeds in hot air from vents in the side of the popping chamber, as opposed to a grate in the bottom. (One with the single grate in the bottom does not force enough air to keep the coffee from burning and would be a major fire hazard). With this in mind, take a look around the marketplace and see what’s around. Brands of poppers to look for are 1) Proctor-Silex Popcorn Pumper and Poppery II by West Bend.
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    Modify it for roasting coffee (optional).
    • The plastic lid that comes with the unit may be unsuitable for its new role - it might melt, so throw it away.
    • Extend the chamber to roast larger batches. Glue an extension made from a food tin to the top of the unit using epoxy resin. (See Tips for alternate method.)
    • Make a simple lid from a kitchen sieve and a flat panel with holes in it (such as pieces of meccano) to collect the chaff.
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    Buy the beans. You need raw green coffee beans to roast. Luckily there are a lot of places you can get these from. Search the Internet and shop around. Three of many sources are Gen-X Coffee, U-Roast-Em, and Sweet Maria's. (You can insure the future of coffee growers by buying only those beans from sites that support Fair Trade practices).
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    Ventilate your work area. While the wafting coffee aroma can be wonderful in small doses, filling the house will soon affect furniture and carpets causing them to emit an unpleasant odor. Ideally, roasting can be done outside.

Method 2
Roasting

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    Weigh out the green beans. By weight, green beans to roasted beans should be weighed at a ratio of about 1.2:1. A larger volume of green beans will result in a slightly longer roasting time. Just a few scoops might provide a very light, open flavor and increasing the volume will offer more depth. See the Tips below for some guidelines.
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    Pour the beans in the roaster. Stick around - watch, listen and smell as the roast progresses. Watch as the sugars slowly caramelize, the water evaporates and the oils begin to cook. After about 2 1/2 minutes of roasting, you’ll hear the beans begin to crack. At about 4-6 minutes, the second crack occurs and small shards will come off the beans, creating a crater appearance on some of the beans.
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    Check the beans often Remove the filter if you’ve fitted one on (it will be very hot!) and peer into the roaster. If you have a metal measuring scoop you can simply lower this into the popper to take a quick sample to judge for color of the beans.
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    Stop roasting once you've got beans of a color you like. When you choose to stop the roast is entirely up to you but a good place is just into the second crack. After about 5 minutes you’ll have a good medium brown roast, and after 6 1/2 minutes you’ll have a great, dark, shiny roast. Any longer than this and the beans will start to burn. Just experiment with a few batches and you’ll soon discover what you like/dislike.

Method 3
After Roasting

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    Cool the beans quickly as soon as they are finished to stop further cooking. Put them into a sieve or a colander and take them outside, then stir them around with a wooden spoon (getting the air flowing around them) or pass them from one colander to another. After a minute or so they will have cooled to around room temperature. Alternatively, once you get to know the process, you can stop the roasting prematurely and let them continue to roast the few moments as they cool in a kitchen bowl. Never use water to cool down the beans, as water will affect the oils of the beans that give then their flavour.
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    For the best results, rest the beans for at least 24 hours to let the excess C02 escape (called de-gassing). Put them into a tin with a loose fitting lid and keep away from strong flavors.

Tips

  • Some sites have charts for varying degrees of roasting. Each bean is different.
  • A suitable popper can sometimes be found at a thrift shop for less than $5.
  • Roasting in a non-enclosed space, shielded from the wind, is preferable. There can be a lot of smoke.
  • It’s wise to invest in a timer so that you can keep track of the progress of the roast.
  • Your measurements may vary depending on the size and variety of bean you roast but shouldn’t be too far off from these:
    • GREEN BEANS ROASTED BEANS DOUBLE SHOTS (16g)
      78g 64g 4
      97g 80g 5
      117g 96g 6
  • If you don't want to use epoxy measure the width of the popper chamber. At the supermarket check out the foreign food section. Many European cans come in differing widths. The poppers slope inwards, slightly, down to the bottom. The can will need to stick up about eight inches. So a can 10 or 12 inches (25.4 or 30.5 cm) long and the width of the popper will slide in until the tapered sides grip it and hold it in place.
  • Alternately you can cut a vertical slit into the rim of a slightly oversized can with a pair of tin snips. This will allow you to taper the width of the can allowing for a nice tight fit into the popping chamber.

Warnings

  • Never use an extension cord, unless it has a ground pin (the third and circular hole) as well.
  • This is done entirely at your own risk. You are using a domestic appliance in a manner for which it was not designed and will void your warranty immediately. In addition you are dealing with high temperatures and combustible materials. Supervise the process at all times. Be extremely careful when handling hot items.
  • Never leave roasting coffee unattended.
  • The can will get hot during roasting! If you used the non-epoxy method, you will need to use an oven mitt or a pair of pliers move or reposition it.
  • Don’t roast more than you can use in a few days. Coffee tastes best 2-7 days from roast.

Things You'll Need

  • Popcorn popper(s)
  • Wire basket(s), fine mesh
  • Green, unroasted coffee beans
  • Colander
  • Food tin (optional)
  • Epoxy resin (optional)
  • Kitchen sieve (optional)
  • Meccano (optional)
  • Metal measuring scoop (optional)
  • Wooden spoon (optional)
  • Tin with a loose fitting lid (optional)
  • Timer (optional)
  • Power strip (optional)
  • Fan for cooling (optional)

Sources and Citations

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