For any aspiring barista to the thought of roasting coffee beans at home probably seems like a far-fetched impractical idea. Let’s be honest you’ve probably only just mastered the inverted AeroPress and the Chemex pour-over, so roasting fresh coffee beans at home is taking your novice coffee skills to a whole new level.
I get it. You think you’re not ready or capable of doing it but learning how to roast coffee beans at home isn’t as complicated as it first sounds. It’s pretty easy!
Have I sparked your interest?
If roasting coffee beans at home sounds like something you want to try, you’ve landed on the right page. In this article, I’ll show you how to roast coffee beans at home, but don’t worry, I’m not going to overcomplicate the process; this is completely beginner-friendly.
I will show you a few basic ways to roast beans, as well as some good home coffee bean roasters to get you started and roasting coffee beans in no time at all. So, are you ready to get your Roast on?
How to Roast Coffee Beans at Home
Before you even think about roasting coffee beans at home, you need to get your hands on some green (unroasted) coffee beans. Depending on where you live, this can be pretty easy or like finding a needle in a haystack.
Luckily buying green coffee beans online can be an excellent place to start if they aren’t readily available to you locally. Here is a good green coffee bean selection for starters, or you could try an online coffee subscription service.
The primary process of roasting coffee at home and anywhere for that matter is simple, take green (unroasted) coffee and turn it brown so that the natural flavors and oils are released from the beans. The DIY at-home approach is an easy way to get started, and with a few simple items from around your home, you can begin roasting!
Some of the recommended ways to roast coffee include using a simple iron skillet on your stovetop or re-purposing a hot air popcorn popper, or if you’re feeling adventurous and want to unlock your inner MacGyver, you can even make yourself a custom coffee roaster (maybe not a good idea there’s no need to involve the fire service or risk losing your eyebrows).
Below is the popcorn popper method and the stovetop method, both of which are favorite ways to roast coffee at home for beginners.
Roasting Coffee in Popcorn Popper
One of the best ways to roast coffee beans at home is to use a popcorn popper. The popcorn popper makes the perfect home coffee roaster, and the good news is you’ve probably already got one gathering dust in the basement or at the back of a cupboard. So there shouldn’t be any need to fork out some cash to get started with this method.
- Set up your popcorn popper in a ventilated place, ideally near an open window or kitchen exhaust fan. Also, I find that having an overhead light is beneficial to see into the popper to judge the Roast accurately. Turn it on so that it’s preheated (before you add your green coffee beans).
- Start by adding your green coffee beans into the popcorn popper chamber. Keep adding the beans until they are barely moving around. If the beans are not moving, you’ve added too much, and you will have to remove some. It would be best if you kept the beans moving otherwise, they’ll burn, so don’t be afraid to use a wooden spoon to encourage the coffee beans to move. As a rule of thumb, a typical popcorn popper should hold around 4 oz. (2/3 to 3/4 cup).
- Once you’ve got consistent movement place on the popper lid. However, keep an eye on the beans to ensure that they are continuously moving.
- Put a large bowl under the popper chute to collect the chaff that will come out of the machine’s spout. To help keep the chaff in one place, you can use a wet towel and put it inside the bowl (the chaff will stick to it).
- After about 3-minutes, you should hear your first cracking and snapping sound coming from the popper. You’ll also notice that the aromas will start to change. Make a mental note of these aromas because remembering what smells occurred at certain stages will be helpful for tweaking your roasting in the future. Also, keep an eye on your coffee beans and monitor the color changes carefully.
- Depending on the type of popcorn popper you own, a light roast should take roughly 4-minutes, and at the 6-minute mark, darker roasts will start coming through. The changes in the different types of coffee roasts will happen very quickly, so make sure you’re constantly monitoring your beans. I recommend removing the coffee beans when they are a tad lighter than the Roast you desire because the roasting process continues until the beans are cool. When removing the beans, make sure you do it quickly. If not, you may find that the beans get burnt on the edges of the popper.
- The roasted coffee beans are going to be hot so use oven mitts when handling the popper. I recommend pouring the coffee beans into a colander to help cool them down quickly.
- While the roasted coffee beans are cooling, keep them out of direct sunlight and away from any moisture. Once cool, place the beans into a Mason Jar or any coffee storage container that has an airtight seal.
But (there is a but) don’t seal the jar yet. Wait for 12 hours to allow the freshly roasted coffee beans to vent off some C02 and degas, and then you can close the lid. The coffee beans attain their peak roughly 12 to 24 hours after you roast, and they will keep fresh for weeks but ideally, for the best drinking experience, use the beans in under a week.
Stovetop Coffee Roasting Using an Iron Skillet
Everyone has an old iron skillet pan lying around in their kitchen. If you haven’t got a popcorn maker or you don’t want to invest in one just for roasting coffee at home, this method is for you.
The stovetop coffee roasting method is probably one of the most convenient ways to roast coffee at home. Still, it’s also one of the more challenging roasting techniques to master successfully.
I like to use a cast-iron skillet but to be honest, and you can use any metal pan with a round bottom that is thick and also doesn’t have any non-stick coating; stainless steel, carbon steel, and my favorite cast iron are all excellent choices for roasting coffee beans.
- If your stovetop has an extraction fan, now is the time to turn it on because it’s going to get all smoky; it might be a good idea to open up a window as well.
- Grab your chosen thick base pan and place it on your stovetop over medium heat (around 450F should be okay). Each stovetop is different, so trial and error are key until you find the “sweet spot” with your burner temperature.
- Slowly start to add your green coffee beans to the pan. I would recommend starting with around ½ a cup. You’ll want to have enough in your pan so that you can quickly stir the beans and constantly monitor them so that they don’t become burnt (trust me, it only takes a split-second for those beans to burn if you’re not paying attention).
- Keep slowly moving the coffee beans around the pan (you don’t have to be too aggressive, just don’t let them sit in one spot).
- You should start to see your coffee beans transitioning through the various color changes after roughly 8-10 minutes (see further down the article). They will go from green coffee beans to yellow, golden brown to light brown and light brown to dark brown. If you don’t see a slow, gradual change and your beans turn dark brown quickly, you may need to adjust your heat level to maintain an even progression next time.
- You should hear the first crack and pop after 4-5 minutes; this is a light roast. Your roasted coffee beans are drinkable at this stage, but it’s up to you to determine if it’s to your liking. Also, remember that the beans will continue roasting and darken even when removed from the heat, so always remove them a shade or two lighter than where you want them to be.
- If you continue roasting your beans, they will continue to darken, and you should hear a second crack at around the 6-7-minute mark. For me, this is when I remove the beans because roasting for much longer than this will result in burnt bitter coffee beans (yuk!) that will most probably have lost all of their caffeine goodness!
- Pour your beans into a colander, then stir and shake to remove any loose chaff and debris, plus this will also help cool them down. Once cooled, place the beans into your Mason Jar or airtight container but do not seal. Allow the roasted coffee beans to degas for 12 hours before you close the lid; I always like to write the roast date on the jar too!
What Happens During the Coffee Roasting Process?
Any coffee geek will tell you that there are ten levels in the roasting process. Knowing these different coffee roasts will help you to gauge when your coffee beans are finished. When roasting coffee beans at home, which level you decide to reach and stop in the roasting process is entirely up to you.
Green coffee beans change extremely fast during the roasting process. When you roast coffee, the moisture is forced from the bean, causing it to dry and expand.
During this process, many of the sugars found in the coffee beans are converted into CO2 gas, while other sugars are naturally caramelized, which brings out some of the flavors that we love in the coffee. When the roasting process is complete, the green bean will be transformed into a brown bean that’s roughly 18% lighter while being 50 to 100% larger than its original state.
The 10 Stages of Roasting Coffee
1. Green: The starting point, your coffee beans will still have their pure green essence, even as they begin to heat.
2. Yellow: In the second stage, you’ll notice that your beans start to turn a yellowish shade, and they will begin to emit a grassy odor.
3. Steam: In this third stage of the roasting process, steam will start to rise. This steam is the moisture found in the coffee beans evaporating.
4. First Crack: Now you are beginning to roast. At this stage, the sugars in the coffee beans start to caramelize, and a distinct cracking can be heard.
5. City Roast: A few seconds after the first crack, your beans have reached the City Roast level. This is typically the first roast level acceptable for grinding and brewing.
6. City Plus Roast: As the sugars in the coffee beans continue to caramelize and the oils start to disappear, the coffee beans will begin to swell in size. This roast level is a common and popular roast to use.
7. Full City Roast: This is an even darker roast than the above City Plus, and your coffee beans are most probably on the verge of a “second crack.”
8. Second Crack: When you reach this roasting stage, your beans will undergo a more violent second crack. This stage is the Full City Plus Roast, and your beans will look dark, but we are not quite at the dark roast stage yet.
9. Dark Roast: This is the darkest Roast that is drinkable. At this roast stage, the sugars will start to burn, and the overall structure of the beans will break down. You will also begin to notice heavy pungent smoking coming from the beans. Sometimes referred to as the French Roast, this is the utmost limit of roasting coffee beans.
10. Burn: At this stage, you can forget it, the smell will go from pungent to terrible, and the beans are now well and truly burnt. They will no longer resemble coffee beans but rather small, useless pieces of charcoal. Try to avoid this roasting level (please!).