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Roasting is what gives our lovely coffee beans their flavor, but if you’re like me you’ll want to learn how to roast coffee beans at home. Well, look no further!
While you could make coffee from unroasted beans, it wouldn’t taste good at all. In fact, it’d probably taste so bad you wouldn’t be able to take more than a couple of sips.
When beans are roasted, a number of physical and chemical reactions take place. This drastically changes our small, virgin beans into the rich coffee we know and love.
When coffee is roasted, sugars that are locked within the bean undergo changes. First and foremost, some of it is caramelized. Along with coffee oils, this is what gives your bean its complex flavor. The rest is converted into gas. But we’ll talk more about the chemistry of the roast later on.
What Happens During The Roast?
The Stages Of Coffee Roasting
Coffee roasting is a series of stages. The minimum goal of a roast is to get the beans to a level where the infusion can be drunk without gagging. However, roasting has become an art form. By noticing the subtle differences in color, aroma, and size of the beans, we can achieve different levels of roast.
These different levels have their own characteristics. The most notable is their increasing intensity in flavor from one level to the next, but also in how visually dark the beans become. In the final levels of roast (dark roast), the beans actually become shiny; as if they had been varnished.
- Green Beans: You’ve just started, your beans are beginning to warm up.
- Yellow Beans: After a short while, you’ll notice that your beans will change from a green color to a yellowish color. Take a sniff, you’ll notice they kind of smell like grass.
- Steam: As you continue to roast your beans, the water that naturally exists inside begins to evaporate into steam. You’ll actually see the steam rising from your beans.
- First Crack: After a little while, you’ll hear an audible crack. When you hear this, you know the actual roasting process has begun. While you can finish the roast here, it is not recommended. This is lighter than light roast, sometimes called a ‘cinnamon roast’, and tends to have a very sour flavor. Not recommended.
- Light Roast: Sometimes known as a city roast, this is the first level of acceptable coffee flavor for most people. This follows the first crack, and the beans should be a light brown color.
- Medium Roast: Sometimes known as a full city roast, this is one of the most popular roasts of coffee. At this stage, the sugars within the bean have really started to caramelize and the bean will begin to swell.
- Second Crack (Medium-Dark Roast): At this stage, your beans will crack once more. The sound will be much louder this time. Here we have a medium-dark roast, bringing a greater intensity of flavor without burning the sugars. This, along with the medium roast, is a very popular roast level.
- Dark Roast: Sometimes known as the French roast. The caramelized sugars will begin to burn, but not so much that it ruins the flavor. You will also notice more smoke, which will have become more pungent.
- While there are roast levels beyond this (Italian and Spanish roast), they aren’t popular. Consider your beans burnt beyond the dark roast.
For an in-depth discussion about the different grades of coffee roast, take a look at my post ‘the best coffee beans’. Here I talk you through the different roast levels, as well as how to find the best roast for your taste buds.
What Is The Chaff?
When your beans are roasting, they shed a layer of skin that gets left behind. This is known as the chaff. It has no benefit at all in the brewing of coffee, so it’s important to separate it from the roasted beans.
It’s best to wait until your beans have cooled before you attempt to remove the chaff. This will prevent any nasty burns.
If you live in a windy area, a good way to separate it from the beans is to take it outside. In a large container, pick up the beans and let them fall back in. The chaff is much lighter, so should below away in the wind as you do this. It’s a very traditional way of doing this, and is very effective if only a little messy.
A tidier way of separating the chaff from your bean is to use two colanders. Dump your beans into one of them and then pass them back and forth between the other. The chaff should begin to fall through the holes and into a garbage bag or a bucket beneath.
Whatever method you choose, don’t worry about leaving a little chaff. If it’s only a little, you won’t notice a difference in the flavor of your brewed coffee. Just try to get as much out as possible.
Green Beans Are Vital
Perhaps the most important ingredient in roasting coffee is coffee! But not any old coffee will do. You need green, virgin coffee beans.
You can’t roast regular coffee you buy in the store because it’s already roasted. So you’ll need to look a little harder to find them. They can be bought online or through specialist suppliers.
You’re looking for consistency here. You want beans that are uniform in size and color. This will produce good quality, consistent roasts so that each coffee bean will produce the same flavor. While you can totally play around with blends of coffee when roasting a specific batch you need to keep everything uniform.
You also need to make sure that you’re buying beans that have already been peeled. When coffee is harvested, they’re actually little red berries. This outer shell is peeled to reveal the green bean within. You don’t want the red berries, you just want the beans.
At Home Roasting Methods
So there are 4 different types of coffee roasting that can be done at home, all with their own pros and cons, let’s have a brief overview.
- Pan Roasting Coffee Beans
- Oven roasting Coffee Beans
- Roasting in a Popcorn Popper
- Roasting in a Home Coffee Roaster
They are pretty self-explanatory. Pan roasting is roasting in a pan, usually a cast iron skillet. Oven roasting is roasting beans in the oven, and so on. While all of these are valid roasting methods, the one I’ll show you today is how to roast coffee beans in a pan, which is my favorite method besides using an actual coffee roaster.
So what’s wrong with the other options? Well, oven roasting coffee beans produces far too much smoke for me. While pan roasting produces smoke as well, if your room is well ventilated you should be fine. But when you roast beans in the oven, that smoke builds up and can be overpowering when you try to take them out.
The popcorn machine method, which I see often on the web, is a joke in my opinion. While you can get success with this method, I think it’s just too dangerous and not cost effective. There is too much chance of starting a fire, as well as the fact that eventually you will break your popcorn machine after a couple of months of roasting.
But surely the best method is using a purpose built coffee roaster, right? Right! However, they’re either so damn expensive, or ridiculously difficult to use.
If you’ve got $5k to drop on your hobby of roasting coffee at home, go for it! Otherwise, you’re stuck with some of the weird and wonderful discount coffee roasters you can find on the web. Some are literally just rebranded popcorn machines. Others will come with incomprehensible instructions, or a manual that is written entirely in Korean. Not so simple after all.
Let’s opt for a method that we can all have a go at. We all have a stove top, and most of us have a skillet (if not, you can pick one up super cheap). These are all you really need, besides scales, a whisk and a lazer thermometer.
But this method is difficult in it’s own way, and will take a lot of practice to master. Even after many attempts, you are still likely to get an uneven roast. But hey, it’s YOUR uneven roast, you know?
So, unfortunately, there is no cheap and easy method. Well… other than buying beans that have already been roasted.
Once you’ve roasted your beans, cooled them and removed the chaff, you’ll need to store them properly.
Oxidation is the roasted coffee bean’s worst enemy. If you let air get to them, it’ll destroy the flavor. This is why you see coffee beans sold in heavy-duty bags.
There are various ways you can store your roasted coffee beans, and for a full list of them take a look at our types of coffee beans post. I set out the best ways to keep your beans nice and fresh.
A Few Words Before We Begin
Before we start, there’s just a few more things to keep in mind.
While this is possible, I really don’t recommend it. In my experience, it produces a very, very uneven roast. It makes pan-roasted beans look like professionally roasted coffee.
While this might not sound terrible, it actually is. When we roast, it’s important to produce a batch of beans that are as uniform as possible. This means your first cup of coffee will taste the same as your last.
While blending is most definitely an interesting art form in itself, this is a conscious effort to produce an interesting flavor profile. If your actual roast is wildly inconsistent, you risk a batch of beans that don’t taste good at all.
You’ll also find it very difficult to reproduce a particular flavor, even if you do find it palatable. So for that reason, I never recommend it. If you’ve had success using a microwave, let me know in the comments section below!
Using a Popcorn Machine Safely
As I said above, using a popcorn machine to roast coffee can be dangerous. Because they’re not designed for roasting coffee, they’ll often break after a couple of months of regular roasting anyway. This ultimately makes it a less cost effective way of roasting, because you need to factor in the need to replace it regularly.
But if I absolutely can’t dissuade you from trying this, it’s really important to get a popcorn machine that is designed to heat the corn from the sides of the machine. If you use one that heats from the bottom, you’ll get an uneven roast. At worst, it can even ignite chaff and cause awful fires.
It’s also very important to keep the popcorn machine clean. You don’t want to leave a buildup of chaff because, again, it’s a huge fire hazard. I also wouldn’t ever leave the popcorn machine unattended.
Better yet, don’t use a popcorn machine to roast coffee, geez!
How To Roast Coffee Beans
- Cast Iron Skillet
- Stove/Hot Plate
- Balloon Whisk
- Laser Thermometer
- 1 Bag Unroasted Green Coffee Beans
- 1 Airtight Container
- Set up your workspace. Gather all your equipment, as well as your beans. The number of beans you’ll need will depend on the size of your skillet. Pour some green beans into the skillet, making sure you have no more than a few layers of beans. This is important for an even roast.
- Make sure your workspace is well ventilated, as there will be plenty of smoke. Place your skillet onto the stove and turn it on. You want to reach around 340-350F before you can proceed. Play around with the stove temperature until you reach this temperature. The best way to measure temperature is to use a laser thermometer.
- Now our skillet is at the right temperature, we can add the beans. Once you’ve added the beans, your skillet will drop in temperature. You can play around with the heat to get it back up to around 340-350F. OPTIONAL: At this stage, you can start a timer on your smartphone or just clock watch. Then, once you’ve finished, you can mark down how long to roast your coffee beans for next time.
- Once your beans are in the skillet, you must begin whisking. Make sure to work quickly, although try not to lose any beans. By using a whisk, we can rotate our beans in layers, as opposed to just moving them around the pan. Whatever you do, just don’t stop whisking.
- As you whisk, you’ll notice the coffee will begin to change color and there will be a lot of smoke. Continue roasting your coffee, agitating it with the whisk constantly. Eventually, you will begin to hear your beans cracking. This is the first crack, and you’ve achieved a light roast. You do not want to take it much further than this. While we could theoretically take it all the way past second crack, you’ll likely burn a lot of your beans before you get the majority of them to a dark roast.
- Once you are happy with the consistency and color of your beans, remove the skillet from the heat and spoon your beans into a bowl.
- Remember when we talked about the chaff? Well, it’s time to remove it! There are lots of ways to do this, and you may wish to do your own research to find the best method for you. However, I would always recommend doing it outdoors on a nice day. My method is to pass the freshly roasted beans between a bowl and a sieve. If you drop the beans from a height, it will allow the chaff to float away in the wind, as it’s much lighter than the beans. Once you’ve removed the chaff, your beans are ready to grind and brew, or store in an airtight container!
Is this coffee roasting method full proof? Definitely not. Will you get the most even roast with a skillet? Unlikely. But is it the easiest and cheapest method to start with? Absolutely! This is why I always recommend it to a first-time roaster.
There are lots of coffee roasting methods, probably way more than I’ve even mentioned here on this page. I encourage you to do more research, especially if you’re looking to take your roast to the next level.
Ultimately, what works best for me may not work for you. But if you’ve never roasted coffee before, this method is a great first step in a complicated aspect of the coffee world that we all take for granted.
Now you’ve roasted your own coffee beans, why not learn how to grind them, and then make use of the coffee? Our coffee brewing skills will teach you everything you need to be an at-home coffee connoisseur. Check us out on social media as well!