Home Coffee Roasting with an Air Popper

If you want really fresh coffee you can buy from local roasters or just roast it yourself. This is a lot easier to do then it sounds. First thing you need to do is to get yourself an electric popcorn maker, the Nostalgia one pictured is a good option. If you buy it from Sweet Maria’s for $20 it will include 4 pounds of green coffee for you to roast, this is a great deal because normally the popper alone around $20 at retailers.

Below is what you will need, hopefully you already have some of this at home. There is a video below, but I always learn better when I can read the steps and then watch the video.

At its basic meaning roasting is the application of heat, you can apply heat to coffee beans many ways. Here are some other methods to roast coffee you can read more about online, but I think using the air popper is the easiest (and cheapest). Most people outgrow the air popper mainly because they want bigger batch sizes or more control over their roast.

Coffee pops or cracks when roasting, twice actually. The time it is called First Crack and it is louder and more pronounced, the second time is called Second Crack and it is a little quieter and faster.

In the coffee roasting world there are different terms for roast levels than what you are used to seeing. There are more than these, but I will focus on the most common ones and the ones in my comfort zone for roasting.

  • City Roast – At or near the end of First Crack, City + Roast allows for a little more development –420-430F – This would be called a light or medium roast
  • Full City – Right Before/Beginning of Second Crack, Full City + is when the second crack is “rolling” or popping regularly (think of microwaving popcorn, this isn’t the first outliers this is when it is really popping quickly) – 430-440F – This would be called a medium or medium-dark roast

The temperatures are approximate and you will see different guides vary a little. For my purposes I try to end a City Roast around 426F and a Full City Roast around 437F.

The coffee roasting process will create a lot of smoke and chaff (coffee skin) that flies all over the place. Because of this I almost always roast outside. Read below for tips on roasting indoors.

Many of the professional drum roasters have sensors and settings for temperature, heat, drum speed, air flow and many other things can be tracked and adjusted on the fly. With an air popper we only have on and off so we are limited (there are videos out there to show you how to mod these things, but I don’t mess with that) in our controls. The main things we have is to go off are sight, sound, smell and temperature, that is what the laser thermometer is for, so we can measure the center of the bean mass.

Here is some more information about roast levels and roast data. Here is also a handy roast card.

Ok, that was a lot of background info so let’s start the process. Please read this entire post before your first roast, things move pretty fast and you won’t have time to read as you go. The total roast times for an air popper can vary between 4-7 minutes. Coffee roasting is a fire risk, always watch your roast and never leave it unattended.

Below is a video of the process, I don’t check the temperature or agitate as much as normally would to get you a better view of the roast progression. Click here for the non-narrated version if you don’t want to hear me talk.

  1. Read the description of the green coffee, if you buy from Sweet Maria’s or Happy Mug it will have some great roasting and tasting notes on it. Determine what your target roast level is. City, City+, Full City or Full City+ unless the bean specifically calls for something darker than this, I wouldn’t go darker than a Full City + roast. When you go that dark you really start to lose the aromas and notes in the coffee and just get bitter Starbucks-like coffee.
  2. Measure your batch size with a scale, I recommend between 2.5 and 3.5 ounces. I usually roast about 3.2 ounces per batch, because I am buying 1 and 2 pound bags and that will get me 5 or 10 even sized roasts out of the bag.
  3. Pre-warm your air popper, I usually warm it for a couple minutes until about 330F. The pros use environment temp (ET) and bean temp (BT) probes. We don’t have a good way to track the ET in an air popper, but the BT can be checked with our laser thermometer.
  4. I roast in a warmer climate so I always leave the lid off of my air popper to prevent the ET from getting too warm. You should only do this if roasting outdoors.
  5. Turn on your timer and pour the beans into the air popper and agitate about every 5-10 seconds, I hold the lip of the air popper where it doesn’t get as hot and agitate the beans in a vertical motion to try to get the beans to cycle from top to bottom and bottom to top to promote even roasting. I keep doing this until the beans are moving freely on their own. I still agitate a little when the beans are moving and cracking every 30 seconds or so, sometimes more if I feel the beans are spinning and not necessary moving from bottom to top.
  6. As the roast is progressing the beans are losing weight and you will notice drying, yellowing, smoke and the smell changes. At this point chaff may be flying everywhere, this is when I take my cheap fan and turn it on to blow all the chaff away from me and also keep the ET a little lower with the airflow. Coffee will lose about 20% of its weight during roasting.
  7. Soon you will hear your First Crack, then first crack will start rolling (think popcorn), the earliest I recommend ending a roast in an air popper is when first crack ends, where it has stopped or slowed down to less than one pop every 10-15 seconds.
  8. I usually roast about 30-45 seconds past the end of first crack since lighter roasts levels are harder to do well on an air popper due to the lack of controls. Bean temp will be around 430F.
  9. If you choose to go to second crack you will hear that as well and can decide to end the roast right when it starts at a temperature around 440F. I try not to let second crack go into rolling unless the notes suggest it.
  10. At this point when you are ready to end the roast turn off your timer and air popper and pour the beans into your sieve. Place the fan under your sieve and start transferring the beans between the two sieves while the fan is blowing under them. This will help cool the beans and blow away any residual chaff. You want to do this until they are cool enough to touch with your hands.
  11. At this point go through and discard any deformed and empty looking beans and pour them back into your cupping tray or a pan for more cooling.
  12. Take notes about your roast after and/or during your roast. Record the type of coffee, the date, the temperatures, when was the first crack, what was your roast level (I’ll note something like First Crack +30), what was the finish time of your roast so in the future you can have a baseline for when you taste it. Maybe next time you want to roast a little lighter or darker however don’t get stuck on your roast times with an air popper, trust your sight and smell to know how your roast is progressing.  
  13.  Factors like the type of beans, ambient temperature, humidity, level of agitation will all impact the roast time so it may vary between roasts even when all other factors are the same. I have two Nostalgia air poppers I use and the red one roasts faster than the blue one, even though they are the exact same air popper from the same company just in different colors.
  14. Some roasters suggest that coffee needs to degas for at least 12-24 hours before you can brew it. Do not store them in an air tight container for the first 12 hours, you can put them in a mason jar (out of sunlight), but don’t screw the lid down all the way.

You can do another roast after this, but I would not recommend doing more than 2-3 roasts without letting the air popper cool down completely (which is why I have two). Also, roasting coffee in your air popper will void the warranty, but for $20 what did you expect?

There are videos out there of how-to mod the power levels on your air popper, I don’t recommend doing this. If you think the power level is too high you can try using a long extension cord or power strip to try and reduce the power level. You can try to pry the air vents to open more for increased airflow, but I haven’t tried this.

If you live in a cold climate, it may not be possible to roast outdoors. You can try to use the lid to keep the warmth in or build a small enclosure to keep the warmth in roasting outdoors. If you are doing this indoors make sure you have really good ventilation, open windows, run a fan, roast under a range hood if possible. To control chaff, use the air popper with the lid and aim it at your sink (spray the sink down a little so the wetness will cause the chaff to stick) or you can also do this with a large pot or bowl.

Congratulations, you have roasted your first coffee. It will be hard to wait the 12-24 hours before you can grind and brew it, but it will be worth the wait.

Now that you’ve roasted your own coffee check out some other posts on how to improve your coffee experience:

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