This is our preferred method for starting your DIY coffee roasting adventures. We have found the popcorn popper to be the easiest, least expensive and most effective way to start roasting your own coffee.
The hot air popcorn popper is a simple but effective way of roasting coffee at home. This method breaks the coffee roasting process down to a very basic form; apply heat to the raw coffee beans until you have achieved your desired roast level. With a little practice you can use this technique to consistently produce exceptional coffee. Because popcorn poppers are not designed to roast coffee and because they are an inexpensive small electronic device their performance varies greatly. You can have three of the same model popper and each one will perform differently. The good news is that is pretty easy to recognize and compensate for the various performance issues that we see with roasting coffee in hot air popcorn poppers. The first step is to make sure you are selecting a model that is suitable for roasting coffee. There are two main factors in that determine whether or not a popper is suitable for roasting coffee.
1. Age before beauty
The older poppers tend to work better, they typically have more robust heating elements, stronger fans, higher wattage motors and the thermostats tend to be set at a higher temperature. The stronger fans allow you place more coffee in the roasting chamber and still achieve a consistent roast. The higher wattage motor and thermostat settings allow you to achieve the full spectrum of roast levels. There are some newer models available that will work for roasting coffee, some you just have to roast smaller batches and others you have to modify in some way. The most common modification is removing or circumventing the thermostat.
2. No holes in the bottom
If you pick up a hot air popcorn popper and look directly down into the chamber you will see one of two things; holes/mesh screen at the bottom or a solid bottom with vents around the bottom portion of the wall of the roasting chamber. The poppers with the solid bottoms are the preferred models for roasting coffee.
These are definitely not hard and fast rules, with a little ingenuity and creativity you can work with just about any of the poppers. Following these guidelines, especially for beginners, will just make life easier and get you roasting your own coffee a lot quicker.
Once you have found a hot air coffee roaster the next step is to turn it on and drop in some raw coffee beans. A detailed method for using a hot air popcorn popper as a coffee roaster can be found here. After your first batch you will have a general idea of how your roaster is going to perform. If all goes well you should have a nice evenly roaster batch of coffee in about 5-8 minutes. If your coffee doesn’t turn out the way you think it should, check our trouble shooting guide. A good scale and a timer will help you determine what is going wrong. While we don’t recommend using time as a way to roast coffee, it is way great tool for trouble shooting your roaster.
Some of the common scenarios you may find are;
This could be caused by a couple of things;
- If coupled with the roast proceeding to quickly, then your roaster is probably over loaded. Try using a smaller quantity of coffee beans. A decent gram scale comes in handy here, but measuring scoops work well too. You’ll want to back off on the volume of beans you start with until you get a nice consistent roast.
- If coupled with a longer roast time (6+ minutes) if could simply be the type of coffee you’re roasting. Some varietals, especially dry processed coffees, have a tendency to roast unevenly. The key here is to look closely at the coffee. Is it scorched and burnt or is it just uneven? If it is scorched then you’ll want to either back off on the volume of coffee your starting with or you’ll need to stir the coffee with a stick or wooden spoon during the first part of the roast. You usually only need to stir for the first 30 seconds or so, as the beans get lighter they’ll starting move freely on their own and your can stop stirring.
- Too Fast
If you are getting into the darker roast levels within 5 minutes, the process is going to fast and the quality of the coffee will be affected. There are a couple of factors than can cause this to happen. The main reason we see the poppers roasting to quickly is because of inadequate air movement. This is either because the roaster is over loaded or because the heating element is just too hot. You have two options here, you can try to increase the airflow or decrease the temperature. Increasing the airflow is as simple as reducing the amount of raw coffee beans you start with. This works, but why reduce the capacity of your roaster if you don’t have too? If you can find a way to reduce the temperature of the roaster you can maintain or even increase the capacity. An easy way to reduce the heat is to plug you popper into a longer extension cord, this restricts the amount of electricity that the roaster can receive which in turn lowers the temperature. Veriacs also work well for controlling the amount of electricity that your roaster receives, they are a little expensive but probably safer in the long run.
If you are 12 minutes or more into your roast and you haven’t heard the second crack then you have a problem. It could be as simple as increasing the volume of raw coffee beans you are roasting, which is great. It could also be that your popper is not capable of roasting coffee. Many poppers, especially new ones, have thermostats built in that shut off the heating element when it hits a certain temperature. Many times this temperature is just at or after the first crack, so the coffee will usually start roasting just fine and then stall. Sometimes you can hear this occur, during normal operation the fan and motor are very even and consistent. When the thermostat starts kicking on and off, you can hear the pitch of the motor change. You might hear the roaster cycling up and down. If this is happening then there is a pretty good chance that your popper will not work. Some models you can remove the thermostat, but it is not recommended. A list of popcorn poppers that we know will work can be found here.