If you walk into an upscale coffee shop you might be intimidated by the sheer volume of fancy roasters and espresso machines they use to churn out one great-tasting cup after another.
And after seeing all of this expensive state-of-the-art machinery we are guessing you may be surprised to learn that all of your favorite coffee beans can actually be roasted using nothing more than a hot air popcorn popper. It’s true.
Hot air popcorn poppers make for excellent coffee bean roasters, especially when using green coffee as your bean of choice. To illustrate this fact, below we have provided a step-by-step guide on How to Roast Coffee Beans using a Popcorn Popper, including the basic materials you will need.
Roasting Coffee Beans in a Popcorn Popper: Materials Needed
Before we dig deep into the process for roasting coffee beans in a popcorn popper, let us first talk about the materials and tools you will need to do the job properly and completely.
The materials needed for home roasting coffee beans using a hot air popcorn popper are minimal. Even better, they are relatively inexpensive, especially when you add up all the money you’ll be saving by NOT frequenting all the fancy coffee shops. Here is what you will need:
Hot Air Popcorn Popper
While most hot air popcorn poppers can handle the job of roasting coffee beans, experts say that a certain design in the popper makes some of them a bit more optimal than others. Therefore, when shopping for a popcorn popper, be sure to look for one that has the side vents inside the machine at the base of the interior funnel.
Some popcorn poppers use a grate design on the bottom of the machine for ventilation, and these do not work as well for roasting coffee beans.
Two Mesh Colanders
Although the cooling process when roasting beans can be accomplished in many ways, the fastest and most problem-free of these is to use two mesh colanders and toss or transfer the beans from one to the other to help cool the sizzling beans. You could, of course, use just one large colander and toss the beans around for a while to cool them, but two truly works best.
NOTE: If you have no colanders, you can actually place the beans on a large cookie sheet to cool, as the large surface area of the baking sheet can actually help leech the heat away from the beans.
One Large Bowl
Any type of large bowl here will do—as long as it is large. This large bowl is essential during the roasting process. It is placed in front of the air chute of the hot air popcorn popper and helps to catch the chaff that will blow off the coffee beans as they are roasting.
The popcorn popper gets very hot during use, even more so when using it to roast coffee beans. Oven mitts are necessary to handle the popper and the lid when it is time to dump the roasted beans into the mesh colander to cool.
You will need a wooden spoon early on in the process with which to gently stir the beans.
Green Coffee Beans
Green coffee beans can be purchased almost anywhere. We recommend you shop around online and try some of the more expensive and exotic beans.
You are saving a lot of money by roasting your own beans, so you can definitely afford to splurge now and again.
Step-By-Step Guide for Roasting Coffee Beans
Now that you have the materials you need at the ready, let’s go forward with our step-by-step guide for roasting coffee beans in a popcorn popper.
Step One: Assembling and Pouring the Beans
From the bag of green coffee beans you purchased, measure out about 85 grams—this is a good starting point for one batch of beans. 85 grams of beans is typically enough to fill a half-cup measuring cup.
After measuring out the beans plug in the popcorn popper and wait for about thirty seconds. This will give the popcorn popper ample time to warm up without becoming too hot. Using the half-cup measuring cup full of beans, begin to slowly pour the green coffee into the popcorn popper.
For a good way to check and see if you have the proper amount of beans in the popper—the proper amount that your popcorn popper can handle at one time—begin pouring the beans into the popper until those beans are just barely rotating inside the machine – just barely.
That’s your maximum amount of beans. If you want, you can unplug the popper and quickly weigh the coffee to get an idea about what the maximum weight of beans is for your particular brand of hot air popcorn popper.
Step Two: Stir the Beans
With the wooden spoon (or similar device) that you have set aside, begin to gently stir the beans inside the popcorn popper. Remember, up until now you have left the lid off of the popcorn popper for the early stages of the roast.
This will prevent the beans from becoming too hot too early. Later you will add the lid to help retain the heat in the popper for the proper roast. At this stage the color of the beans should still be green or just starting to tan.
The smell or aroma will barely be in the air at this point, and if there is a smell it will be a faint odor of sweet barley.
Step Three: Put on the Lid
In step three you are going to want to place the lid on the popcorn popper. Again, this will help the machine retain the needed heat to start and complete the roasting process.
Step 4: Start Collecting Chaff
At about 2 minutes and 30 seconds into the roasting process you should begin to see the chaff, also known as the coffee’s silverskin, start to come off of the beans and out of the air chute. This is when things are really starting to happen.
Be sure to place the large bowl you have assembled under the air chute to collect as much as the chaff as possible. This will help you avoid a big mess in the kitchen, as these light pieces are known to fly everywhere once they begin falling off the beans.
At this stage of the roasting process (2.5 minutes) the beans should take on a cinnamon color—medium to dark tan; and you should really begin smelling the sweet barley aroma.
Step Five: The First Crack
The “first crack” of the coffee beans comes about 4 minutes into the roasting process. You will recognize this first crack by the sound it makes. You’ll begin to hear a din that sounds roughly like a gentle fire crackling in the moonlight.
The first crack is when the internal cell walls of the coffee beans are being fractured by the heat and boiling oils. At this point in the process, your coffee beans are entering the “light roast” or “city roast” style.
Depending on the type of coffee you purchase, the roast can technically be stopped at any time after the first crack begins. However, if you like more of medium to dark roast blend of coffee you should definitely wait a while.
At this stage of the roasting process the beans will take on a light to medium brown color, and the smell will turn from sweet barley to a muted scent of oils cooking—the oils given off by the coffee itself.
The temperature of the beans at this point—once the first crack really gets going—should be about 420 degrees F. Later on this temperature will rise a bit before it subsides.
Step Six: The Second Crack
As we mentioned above, if you prefer a light roast style of coffee you can technically skip this step and move on to step seven.
The second crack of the coffee beans, which will again depend on the type of beans you purchased, will begin about 5 or 6 minutes into the roasting process. At this time, and after a pause in hearing the first crack ending, you will begin to hear a different kind of crack than you heard with the first crack.
This second crack is more muted in nature but a much higher pitch than the former. This sound will also come more frequently, in fact constantly once it begins. This second crack happens when the surface walls of the beans are fractured by what are now tiny little heaters or furnaces inside the beans.
Once the second crack FIRST begins, the beans are now at a “medium roast,” also known as a “Full City” roast. Once again, if you prefer a medium roast you can end the roasting process at this point, or you can wait a couple of extra minutes for the beans to reach the “dark roast” stage—when surface oils begin to show up.
At this point in the roasting process the beans will take on a color of medium to dark brown and the aroma will smell like burning oils and burning organics.
Step Seven: Dumping the Beans
Once the beans have reached the stage of roasting you prefer, unplug the hot air popcorn popper. Using your oven mitts, carefully remove the lid and pour the beans into your colander to cool.
Be very careful here, as the temperature of the beans can exceed 450 degrees at this point.
Step Eight: Cooling and Sifting the Beans
Using one or both of your colanders, begin cooling and sifting the beans by tossing them back and forth. This will aerate the coffee beans and also help to rub off any additional chaff that may still remain.
And that’s it.
Once the beans are cooled and sifted your can store them in an airtight container at room temperature.
Experts say you should let the beans sit after roasting for at least 2-5 days for best results. Then the beans are ready to be ground and enjoyed as delicious home-roasted coffee.