A question we hear a lot at Triple Bar is how to roast coffee at home. Roasting coffee at home is a very rewarding and delicious hobby. It also is very cost effective! Green coffee beans are usually between $5 and $10 per pound, compared to the normal $8-$15 per 12 oz bag that a coffee roaster charges. Below, we’ve outlined the steps you need to get started roasting at home.
1. Buy green coffee beans
Coffee beans come from a fruit called the coffee cherry. This cherry has two seeds in it. These seeds, when dried, can be roasted and turn into the delicious brown coffee beans you know and love. After the seeds (or beans as we know them) are dried, they have a pale, pea-green color. They’re usually pretty small and smell somewhat grassy. If you’d like to learn more about the coffee plant, check out our post.
An important thing to note is that green coffee is full of moisture and when you roast the beans, they will drop in weight but increase in size. Most of the time, the moisture will drop 15-25%, so if you want a 12 ounce yield, you will want to buy around 16 ounces of green coffee.
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If you’re looking for a one-time order, you can buy green coffee beans online at several home coffee roasting websites. A couple of our favorites are:
Once you have your coffee beans, you’re ready to choose a roaster.
2. Buy a roasting device
Choosing a coffee roaster can range from free to very, very expensive. We recommend starting out with a free or cheap option and upgrading as you get more interested in the hobby.
One caveat we should mention is that coffee roasting produces steam and smoke as the coffee is roasted to perfection. If you’re planning to roast indoors, make sure that your space has proper ventilation by opening windows to exhaust the smoke outside.
The most basic way of roasting coffee is on a baking sheet in the oven. Most people have ovens and baking sheets, so we consider this to be the lowest barrier to entry.
If you’re looking for something a bit less kludgy than roasting on a baking sheet, you can purchase a dedicated roasting device like a handheld ceramic roaster. These ceramic roasters can be held over a burner on the stove and heated to roast the coffee. The downsides are that the roasts will likely not be very uniform and you can only roast between 30 and 70 grams of coffee at a time. That’s the equivalent of 1-2 double shots of espresso, which isn’t much coffee. However, if you’re looking for a low-cost way to get into home roasting, this may be a good option for you.
Another low-cost option is to purchase a WhirleyPop. These devices are actually made for popping popcorn on the stove. They look like a big pasta pot with a handle on the side. The handle, when rotated, pivots an arm inside the pot to keep the popcorn moving so that it doesn’t burn. WhirleyPops are often used by hobby coffee roasters because they can help you prevent beans from burning by regularly turning the handle to keep the beans agitated.
The downside to the WhirleyPop is that it was designed for popcorn and not coffee. Therefore, to keep the coffee from burning, you must rotate the handle for the duration of the 8-15 minute roast time. Occasionally, the internal pivot arm may get stuck and you have to shake the popper to keep it working properly.
The next step up is really the first step in actual coffee roasting equipment. These devices were designed specifically for home coffee roasters. They range in price from $180-$700. We recommend investing in one of these roasters if you decide that coffee roasting is a worthy pursuit.
The lowest cost introductory coffee roaster is the Fresh Roast SR500. It is a fluid bed roaster with a fan that essentially levitates the beans so that they are constantly moving around while hot air is blown through them. The device offers air speed adjustments—which helps control the speed of the roast—and a handy chaff collector. Chaff is the skin of the coffee bean that is shedded when the beans begin to expand as they roast. The roaster also has a nice glass container so that you can clearly see how your roast is progressing.
A slight jump up from the SR500 is the SR700. It’s essentially the same roaster, made by Fresh Roast, but adds the ability to track the roast on the computer using specialized roasting software. This type of monitoring is very helpful when trying to fine-tune your roast.
The next step up in this tier is the Behmor 1600 Plus. This roaster looks very much like a toaster over, but has all of the innards of a drum coffee roaster. It features an inner mesh chamber that you’ll fill with beans. After starting the roaster, the chamber will rotate, tossing the beans around to help create a uniform roast. A nifty control panel on the side (which makes it look even more like a toaster oven!) has all of the controls necessary to adjust from the default roast profiles to something more custom. The roaster has a built-in light inside the roasting area to help you see how your roast is coming along. Another great feature of the Behmor 1600 Plus is the smoke reduction unit, which makes it a bit easier to roast indoors. We still prefer to roast in a well-ventilated garage, though. If you’re interested in learning more about the Behmor 1600 Plus, check out our detailed review.
The final roaster in this tier is the Gene Cafe roaster. This roaster features a drum, similar to the Behmor, but has quite a bit more visibility of the roast thanks to an all-glass roasting chamber. The roaster comes in black and cherry red, giving you the option to add a bit of flair to your roasting space. The roaster is extremely quiet, which a nice feature to have. Another useful feature of this roaster is its smoke exhaust system. The outlet tube is perfectly sized to add a dryer duct to it, allowing you to roast inside and vent the smoke outside. We still recommend roasting in a well-ventilated area, though.
There are a few options in the high-cost tier that are much more like standard, industrial drum roasters. These roasters feature a rotating drum over a heat element, which is largely the industry standard. They also have integrated thermocouples which can connect to a computer so you can track and record the progression of your roasts. Our favorite home roasters are the Hottop and the Huky 500.
The Hottop is a small countertop roaster that can roast within 15-17 minutes per batch. Unfortunately, it doesn’t have the ability to connect to a computer, so you have to rely on your senses of smell, sound, and sight to ensure the roast is moving along nicely. The Hottop is capable of roasting up to 9 ounces of coffee at a time, making it perfect for small sample roasts throughout the week. The system uses an electrical heating element to heat the beans, similar to a toaster oven. The Hottop is on the pricier end for what you get, but it’s a very good introductory roaster.
The Huky 500 is our favorite roaster. We may be a bit biased, though, because this is the roaster that we use at Triple Bar for small batches. It can only be ordered through a gentleman in South Korea by contacting him directly. The Huky 500 goes for between $1300 and $1500, depending on your configuration. This roaster uses liquid propane or natural gas and has a dedicated cooling tray for when you drop the beans. Since this roaster is very similar to a commercial roaster, you’ll want to make sure you roast in an area where you can easily ventilate the smoke away. We absolutely love our Huky 500. It’s both a work of art and a workhorse of a coffee roaster.
3. Heat the beans
Now that you’re acquainted with the equipment needed to get started roasting coffee, you’re ready to get started. Coffee roasting is a fairly easy process once you have the equipment set up. To start, preheat your roasting device to approximately 400°F. This is generally a good temperature for starting the roast. Regular thermometers work, but are hard to check temperature because they take awhile to register temperature and you can easily burn yourself in the process. If you don’t have a temperature readout on your roaster, we recommend getting a thermocouple and a voltmeter so that you can check the temperature.
Next, place your desired quantity of green coffee beans into the roasting device, whether that’s a baking tray or a dedicated roasting device like the Huky 500. Be sure to take into consideration the moisture loss when calculating how much coffee you want as the yield. A good rule of thumb is to estimate 25% more than you want as the yield so that you can account for the moisture loss.
Once you’ve weighed out your green coffee and your roaster is at the desired starting temperature, place your beans into/on the roasting device. This is known as the “drop” in coffee roasting. The action gets its name from how roasters usually put the beans in a hopper above the coffee roaster and then “drop” them into the roaster.
The first few minutes of the roast are considered the “drying phase” even though the beans will lose moisture throughout the roast. During this time, the coffee beans turn from green to yellowish-brown. They are defined as being “endothermic” during the drying phase because they absorb energy. As the roast progresses, be sure to continuously turn the beans to prevent them from burning.
After the drying phase, the coffee will turn a darker shade of brown. During this time, Maillard reactions occur in the beans. These reactions are similar to those seen when you brown meat like ground beef. Your beans will continue to get darker until you start to hear a popping sound that’s similar to the sound of popcorn popping. This popping is called first crack. First crack is when the beans have so much pressure built up from the heat and expansion that little cracks begin to form on the beans.
These cracks make the sound and will loosen the skin from the green coffee beans. The thin, papery skin that comes off the bean is called chaff. Chaff doesn’t have much of a flavor, but it’s good practice to try to remove it from the bean. After first crack has finished, most coffee roasters drop the beans into the cooling tray.
If you like your beans a bit darker, you can continue to roast into second crack. It’s less of a popping sound and more of a snapping sound. Second crack sounds similar to branches or twigs snapping. We wouldn’t recommend roasting past a several seconds into second crack. As you roast, the beans will get darker and more carbon-y. Anything past this roasting level will taste rather burnt in the final cup.
When you’ve roasted the beans to your liking, you can dump them into a cooling tray or container.
4. Cool the beans
One of the most important factors in coffee roasting is cooling the coffee after roasting. The reason this is so important is that, after several minutes of roasting, the coffee beans have a very high internal temperature. The beans continue to cook even after they have been removed from the heat source. This is similar to how an egg continues to cook on a stove that has been turned off. To address this over-cooking issue, roasters usually have big fans connected to the container they drop their beans into.
Since you’re going to be roasting smaller quantities at home, all you need is a portable fan, like a box fan, or one of those small clip on fans. You can set this small fan up next to the container that you dump your beans into after roasting. Within a few minutes, your coffee beans will be cool to the touch.
5. Rest the beans
One thing that coffee roasters often do after roasting is “rest” the beans. This is a period of 24-36 hours during which the roaster leaves the coffee to rest so that it can off-gas. Coffee releases carbon dioxide as it roasts. After roasting, there are still lots of gasses that need to dissipate. This rest period allows your coffee to off-gas, making it more flavorful in the process. At Triple Bar, we generally rest our coffees for 1-2 days.
Now that your coffee has had time to rest, you’re ready to pull out your burr coffee grinder and favorite brewer. Be sure to keep a notebook with tasting notes so that you can iterate on your next roast and gradually improve the roast profile.