Coffee roasting is a process that uses heat to activate and unleash the flavors and aroma-forming compounds that are packed in green coffee beans. Roasting also produces and releases gases (CO2), volatile compounds, and moisture from the beans hence increasing the volume, porosity, and solubility of the coffee beans.
Therefore, we have to roast green coffee beans to obtain the flavors and aroma that we enjoy in coffee. The easiest way to roast green coffee beans is the frying pan or cast-iron skillet method that has 10 steps to it.
A metal colander, cast iron skillet/pan, a large container to collect the chaff, a metallic whisk, green coffee beans, a stove, optional infrared/laser thermometer
Here are the 10 steps to follow when roasting coffee beans in a frying pan/cast-iron skillet
- Preheat the skillet. Turn the stove on to medium-high heat and preheat the skillet for 1-2 minutes
- Add the coffee beans. Spread enough green beans to more than fully cover the bottom of the pan. As the beans heat up, they will start to smoke.
- Agitate. Constantly stir the beans with the whisk to even the roast and to prevent scorching
- Observe color changes. The color of the beans gradually changes from green to yellow to light-brown as the beans continue smoking
- First crack. At about 8-11 minutes the beans will start to make a noticeable cracking sound that signifies the first crack. Removing the beans from the pan at this point gives you lightly roasted beans. For darker roasts, continue roasting
- Smoking gradually drops. After the first crack, smoking drops gradually and the light-brown beans progress to browner and darker hues
- Second crack. A second cracking sound will appear as you continue roasting. At the second crack, the beans are significantly larger in size and darker than the first crack. The second crack heralds the shift from a medium roast to a dark roast. Roasting the beans further will lead to smoky and charred flavors
- Remove the beans at any point between the first crack and just after the second crack depending on the roast level that you desire.
- Cooling. Put the beans in the colander to cool down and place the colander on a sink or container to collect the dropping chaff. Gently agitate the beans to expel all the chaff
- Storage. After cooling, keep the roast in an open container to allow off-gassing for 4-6 hours. Put the beans in an airtight bag or container and store them away from direct light, moisture, and heat.
You can use the thermometer to check the temperature of the beans right before you remove the skillet from the stove. This temperature can be a marker for your future roasts to establish some consistency. You can also have a sample of roasted beans to compare with your roast as you continue roasting.
Coffee beans continue to roast for a few seconds after retrieving them from the roaster. Therefore, you are better off removing the beans slightly before they achieve the desired roast level.
The cast-iron method generates a lot of smoke so you are better off roasting the green coffee beans outdoors or open your windows and ensure adequate ventilation before commencing the roasting process.
Other methods of roasting green coffee beans are:
- Oven method
- Using a popcorn popper
- Using an air fryer
- Grill method
1. How to Roast Green Coffee Beans in an Oven
Materials and Equipment
Oven, 1 oven tray, aluminium foil, colander bowl, receptacle, green coffee beans
- Cover the oven tray with some foil to prevent coffee stains
- Turn the oven on to a temperature setting of about 410°F or your desired coffee roast temperature between 356-474°F
- Spread enough green beans to cover the surface of the oven tray
- Place the tray in the oven
- Remove the tray every five minutes to observe the beans and agitate them with the spatula. Open the extractor fan every time you open the oven to take care of the smoke
- When your preferred roast level is achieved, turn the oven off and transfer the beans into a colander bowl
- Agitate the beans to expel the hulls and cool the beans. Collect the hulls in a receptacle.
- Put the beans in a zip-top bag and store them in a pantry as the beans continue to off-gas.
- Clean the oven to remove any hulls
Advantages of Roasting Green Beans in an Oven
- It gives an even roast without scorching the beans
- The temperature setting in an oven makes it easier to determine your roast level
- An oven, unlike a skillet, produces less smoke
2. How to Roast Green Coffee Beans in a Popcorn Popper
Materials and Equipment:
Green beans, a long wooden spoon, a receptacle, a colander
Steps when roasting coffee beans with a popcorn popper
- Fix the popcorn popper in a well-lit place near a window or a smoke vent for adequate ventilation. Keep it away from any smoke detectors
- Have your beans ready (about half a cup) and all the other equipment in close proximity
- Position the chute of the popper over the receptacle
- Switch the popper on and add the green beans
- Stir the beans to even the movement of air around the beans for an even roast. You may stop stirring when the beans are moving freely by themselves. Pay close attention to the cracking sounds and color changes to determine when your desired roast level is achieved
- You can replace the lid of the popper or leave it open to observe the beans. Leaving it open will cause chaff to fly around but it’s a necessary evil before you master how to detect that your desired roast level is ready
- Shut off the roaster and pour the roasted beans on a colander
- Shake the colander and stir the beans over the chaff receptacle to remove all the chaff
- Allow the beans to sit for 4-6 hour to off-gas before storing them in an airtight container or bag
3. How to Roast Green Coffee Beans in an Air Fryer
Material and Equipment
Air fryer, green beans, a colander bowl, receptacle
- Turn the fryer on and set the temperature of about 410°F or your preferred temperature
- Preheat the fryer for about 2-3 minutes
- Remove the fryer basket and add enough beans without filling the basket
- Replace the basket
- Remove the basket every 3-5 minutes to check and stir the beans. Be keen for some popping sounds to signal the first crack (light roast) and the second popping sounds that signal darker roasts
- Remove the beans when you have attained your preferred roast level. Turn the fryer off
- Dump the roasted beans into a colander bowl and stir them to remove hulls
- Store the beans in an airtight container
4. How to Roast Coffee Beans on a Grill
This simple coffee grilling method uses a cast iron pan on the grill. Place the grill outdoors, fire it and follow the steps for roasting green coffee beans using a cast iron skillet as outlined earlier
Benefits of Roasting Your Own Green Coffee Beans
- You have more control over the roast level that you prefer
- It reduces chances of your roasted coffee going stale because you roast only the quantity that you intend to use for a particular duration of time
- You are able to determine the freshness of your coffee unlike buying roasted beans that you can’t be certain when they were roasted
- Some people enjoy the aroma of roasting beans
- Roasting your own coffee can be a psychologically satisfying affair. It’s gratifying when you make your coffee right from the green bean to the drink in your cup.
There are various methods to choose from when roasting green coffee beans at home. If a cast-iron skillet is not available, you can use a saucepan instead and follow similar steps.
If you do not have a colander, transfer the hot beans from the roasting container to a different container and wait to cool for 2-3 minutes. Grab a handful of the beans and shift them from one hand to another as you agitate them with your fingers to drop the chaff. Repeat until all the chaff is expelled.
The air fryer method produces the least smoke and is the most convenient when you have an air fryer at home.
Frequently Asked Questions
How To Store Freshly Roasted Coffee Beans?
The best way to store freshly roasted coffee beans is by putting the beans in airtight zip lock bags or mason jars and placing them in a pantry to allow the beans to degas. The stored beans should be safe from moisture, heat, and direct light.
Use a strainer or colander to cool the beans and remove all the hulls from the beans before packing them in the airtight bags.
It is not advisable to store freshly roasted beans in a freezer because the freezer temperature will stop degassing and the beans will not reach their prime stage. You can, however, freeze the beans after priming: 5-10 days of roasting.
Do You Wash Green Coffee Beans Before Roasting?
Although you can wash green coffee beans before roasting, it is not necessary at all. Washing the beans before roasting has no effect on the final flavors and quality of the coffee. Washing the beans can lead to more smoke when you roast them.
However, some communities such as Ethiopians and Eritreans are known to wash beans to moisturize them before roasting for coffee ceremonies. To wash green coffee beans, put them in a strainer and run water through the strainer as you gently agitate the beans with your hand. Roast the washed beans using a method of your choice.
How Long Should Coffee Rest After Roasting?
Although you can brew coffee immediately after roasting green coffee beans, resting the beans for 5 to 10 days allows them to release most of the trapped carbon dioxide so that the beans are ripe for optimum extraction.
How Long Do You Roast Green Coffee Beans?
The duration of time that you take to roast green coffee beans depends on various factors:
- Roasting method. An air fryer takes a shorter period than an oven
- Preheating your equipment. Preheating an oven, a cast iron, or an air fryer basket before adding the green beans can significantly reduce your roasting duration.
- Roast temperature. Depending on your desired type of roast, the roasting temperature should be between 356-474°F. You are better off presetting a roast temperature that is within this range. Very low temperatures prolong the duration of your process.
- Desired roast level. Darker roasts take more time to achieve than lighter roasts. However, over roasting is undesirable as it degrades the flavors and aroma of coffee.