Learn How to Roast Coffee Beans at Home from a Roaster

Why Roast Coffee Beans at Home?

Whether you love learning and trying new hobbies or you simply want to save some money, there are many reasons why you might be considering roasting coffee at home.

The first benefit that comes to mind is creative expression and freedom. When you roast your own beans, you get to decide which coffee you buy and how dark you want to roast it. Maybe you like light roasts from Ethiopia with notes of jasmine and blueberries, but not many roasters in your area offer this. 

Why not buy some green coffee (raw coffee beans) online and roast it exactly how you want?

By diving into this craft, you will also benefit from always having the freshest coffee available. Roasted coffee is best when consumed within two weeks. After this period, oxidation starts to take its toll on the freshness and flavor.

If you roast your own coffee, you will never have to worry about roast dates or the infamous “best if used by” dates again.

As you begin to fall in love with another side of the coffee world, you will gain an even deeper appreciation for the craft and expand your palate, all while saving money.

One pound of green coffee costs around $8, while a 1-pound bag of roasted single-origin coffee will sell for around $25. Not accounting for a roasting machine or the weight loss that happens during the roast, your coffee budget will last about three times longer!

What Happens to Coffee Beans During Roasting?

If you’ve even been tempted to try grinding and brewing green coffee beans, don’t try it. It simply won’t work. Until coffee beans go through the roast process, they are too wet and will taste like grass.

I’m not using slang… it will taste like actual grass!

Professional roasters usually divide the roast process into three phases for simplicity’s sake. Let’s go through what happens during each one.

Drying Phase

During this part of the roast, coffee beans primarily lose their moisture. Green coffee beans usually have a moisture content of 11-12% that needs to be drastically reduced before grinding and brewing.

This phase starts when you put the coffee beans in whatever roasting machine you are using, whether that’s a pan, popcorn popper, or a dedicated home roaster. While the beans are continuously drying throughout the entire roast, this phase is considered over once the beans start to yellow.

Maillard (Browning Phase)

From the time that the beans start to yellow and darken until the first crack is referred to as the Maillard, or Browning, Phase. The Maillard Reaction is known to be a chemical reaction that is between the amino acids and the reducing sugars, which creates the distinctive flavor of browned food. 

Essentially, this reaction and others like caramelization and Strecker degradation are all happening in unison to create flavor and aroma compounds… you know, the good smells and tastes that you want to enjoy in your cup of joe!

Development Phase

Again, this name isn’t too helpful because the beans are developing during the entire roast. The Development Phase starts at the first crack and continues on to the end of the roast.

The first crack is the audible popping noise that you hear from the pressure within the beans being released, causing the beans to crack open at the surface. Most light to medium roasts will go a bit past the first crack, while dark roasts may go to the second crack and beyond. 

Related Read: 13 Different Types of Coffee Roasts Explained in Detail

In this phase, all water eventually evaporates and sugars break down for more bittersweet notes and reduced acidity. Be careful not to roast for too long, or bitter and burnt flavors will overpower everything else.

Most roasters, like myself, shoot for a specific amount of time in the Development Phase before finishing each roast. This is usually referred to as a percentage of the entire roast time. I’ve roasted coffees with 12% development for fruity and floral pour-overs, and I’ve also gone as high as 20% for some darker roasts.

Recommended Roast Level for Home Roasting

You probably want to get into roasting coffee at home to make your roasts exactly how you like them. Whether that’s a super dark Italian-style roast or a light roast such as a Scandinavian, I believe that you should make your coffee however you like it.

However, if you are just starting out, I recommend that you shoot for around 15-18% development for a medium or medium-dark roast. These roasts are the most forgiving when you go to brew.

If you are a bit overwhelmed with the process and don’t want to measure these percentages while you roast, wait anywhere from 15-45 seconds after the first crack before you stop the roast and start cooling down your beans.

Your water hardness matters too. If you live in an area with particularly hard water, you will need to roast a little darker. If your water is very soft, you can go a bit lighter (1).

When water has more minerals in it, it “blocks” the water from extracting the coffee as well. Very light roasts may taste great when using very soft water to brew, but using all the same variables (amount of coffee, brew time, etc.)  with harder water may taste very under-extracted.

Once you get a successful medium or medium-dark roast down, feel free to experiment!

Where Can You Buy Green Coffee Beans?

Bear with me as we go through one more crucial topic before getting into the nitty-gritty of roasting coffee using three different methods.

The most essential ingredient to roasting coffee is, drumroll please… green coffee beans (raw beans)!

But where can you find some? Since you will be buying relatively small quantities of green coffee beans, you have three main places you can purchase from.

Whatever you do, make sure to get the best quality green coffee you can find. It will make roasting that much easier.

• Online vendors: Websites like Sweet Maria’s and Coffee Bean Corral are trusted favorites among home roasters. They can send as little as one pound of coffee nationwide and offer many origins and varieties. They also come with detailed tasting notes, so you know what your coffee should taste like if roasted well. Or you can choose to buy them directly from Amazon.
  
  
  
• Local roasters: Oftentimes, your local roaster may be willing to sell you a couple of pounds of green coffee. After all, they probably have lots of bags weighing over 100 lbs stacked in storage just waiting to be roasted. I like to grab a bag of roasted coffee when I buy green beans from roasters, so I can compare my final product to theirs.
  
  
  
• Coffee farms: If you’re lucky enough to live in a coffee-producing country, you can go straight to the farm, meet the producers, and see how their coffee is grown and processed. Talk about a unique experience! I’m currently driving through Central and South America doing exactly this, with my home roaster setup in my converted van. Fresh coffee doesn’t get any better than this!

How to Roast Coffee Beans at Home Using 3 Popular Methods

Okay, now that you have your green beans, let’s get roasting!

This is the moment you’ve been waiting for. Take a deep breath and remember that roasting coffee can be as simple or as complex as you want it to be. Start with the basics and go from there.

Today, we’ll explore how to roast coffee using the following methods:

1. Pan or skillet
2. Popcorn machine
3. Home coffee roaster

Important Tip:
I deliberately left out roasting with an oven because it will never lead to an even roast and is very dangerous. You’ll create a lot of smoke and the risk of starting a fire is high. Since the beans can’t be agitated while inside, they will likely become scorched too.

Just trust me on this… pick one of these three methods instead to get started.

When picking a coffee roasting method, you have to consider your budget, the amount of coffee you want to roast, and how much control you wish to have with the machine.

Let’s dive into the pros and cons of each method!

1) Roasting Coffee with a Pan or Skillet

This is the cheapest option, as the price is probably free since you likely have a pan in your kitchen already. If you don’t, well… I have so many questions for you!

I personally recommend that you pick Options 2 or 3 if you want to regularly roast your own coffee, but roasting beans with a pan will give you a taste of the process. It’s very easy to do, but the coffee might not turn out that good.

How to Roast Coffee with a Pan

Equipment Needed:

• Pan
• Whisk
• Timer
• Hot plate
• Two colanders or sieves
• Laser thermometer (optional)

Instructions:

1. Gather the equipment and beans.
   
   
2. Make sure the area is well-ventilated. Open some windows and turn on your exhaust fan if you have one. This method creates a decent amount of smoke, so get your space ready.
   
   
3. Place the pan on the stove and turn on medium heat.
   
   
4. Once the pan reaches around 350°F, add the beans. Make sure that you only go one layer high. You can cover the entire surface of the pan. Start your timer now.
   
   
5. Start whisking and do not stop during the entire process.
   
   
6. After you hear the first crack, roast for 15-45 more seconds. Avoid the second crack, unless you like dark, bitter coffee.
   
   
7. Turn off the heat and put the beans in a bowl.
   
   
8. Toss the beans between two colanders or sieves. This cools down the beans more rapidly and also gets rid of the chaff (the last protective layer of the bean that falls off during the roast).

2) Roasting Coffee with a Popcorn Machine

This is where most aspiring home roasters start their journey if they are on a tight budget.

A popcorn popper is great because it introduces convective heating (hot air) into the roast, which isn’t possible when roasting with a pan. This moving air will also constantly agitate the beans, so you can save yourself an arm workout.

Disclaimer: Using a popcorn machine to roast popcorn probably voids your warranty. Popcorn machines aren’t designed to handle coffee, so expect eventual breakage or damage to your popper.

Another Important Tip:
Additionally, buy a popcorn popper that heats from the sides, don’t buy one that comes with a mesh screen on the bottom. It’s a fire hazard.

How to Roast Coffee with a Popcorn Popper

Equipment Needed:

• Popcorn machine
• Timer
• Two colanders or sieves
• Laser thermometer (optional)

Instructions:

1. Gather the equipment and beans.
   
   
2. Make sure the area is well-ventilated.
   
   
3. Turn on the machine and wait 1-2 minutes for it to heat up.
   
   
4. Put 3-4 ounces of beans in your popcorn popper and start the timer.
   
   
5. Use a long, heat-resistant kitchen utensil to help stir the beans if they don’t move at first. Sometimes beans are too dense from their moisture content and the popper is too weak to get them moving at the start, but with a little bit of help, they will keep moving.
   
   
6. After 3 or 4 minutes, the first crack will happen.
   
   
7. Continue roasting for 15-45 seconds, but turn off before the second crack, or 420°F.
   
   
8. Put the beans in a bowl.
   
   
9. Toss the beans between two colanders or sieves to cool them down rapidly and remove the chaff.

3) Roasting Coffee with a Home Coffee Roaster

If you can afford a $300-$800 investment to start, this is the way to go. Dedicated home coffee roasters give you many more options when it comes to control. Some come with adjustable drum speeds, fan speeds, and heat settings.

Fresh Roast and Behmor are two of the most popular brands among home coffee roasters. Some models even come with temperature readings and preset roast profiles to make getting started much easier.

I use a Fresh Roast SR800 with an extended roast chamber, which allows me to easily roast 250 grams (9 ounces) of green beans per batch. 

If you want more control and customization during your roasts, a dedicated coffee roaster is right for you.

How to Roast Coffee with a Coffee Machine

Equipment Needed:

• Home coffee roaster
• Timer
• Two colanders or sieves
• Laser thermometer or temperature probe (optional, if your machine is not equipped with one)

Instructions:

1. Gather equipment and beans.
   
   
2. Make sure the area is well-ventilated.
   
   
3. Double-check that the chaff collector on your machine is empty and clean.
   
   
4. Put in the beans.
   
   
5. Turn on the machine and start the timer.
   
   
6. Make sure the fan setting is high enough to move the beans at the start.
   
   
7. Add a medium-to-high amount of heat during the Drying Phase. Regulate fan speed and power settings to shoot for a total roast time of 8-12 minutes. This will take trial and error. Don’t worry if your first few batches aren’t great. Mine weren’t!
   
   
8. Listen for the first crack at around 385°F.
   
   
9. Turn off before reaching 420°F (before reaching the second crack) for a nice medium-dark or medium roast. I like to shoot for a development percentage of around 15%.
   
   
10. Start the “cooling” phase if your machine has it. If not, end the roast and put the beans in a bowl. Toss between two colanders or sieves to cool down quickly.

Regardless of which method you go with, make sure you let the coffee beans rest for at least a few hours before putting them in airtight containers. Roasted beans need to off-gas carbon dioxide, a byproduct of the roast, during the first few days, with a majority of it leaving the bean in the hours after a roast.

Wait at least 24 hours before brewing, preferably 48 hours if you’re patient enough.

How to Improve Your Roast at Home

If you’ve tried roasting a few batches and nothing is coming out how you want it to, check the tips on this list.

What you should do…

• Use high-quality green coffee! You can’t make bad coffee taste good by roasting it. Quality in, quality out.
  
  
• Change only one variable at a time.
  
  
• Keep a journal, and try to track the changes you make during the roast so that you can replicate it.
  
  
• Clean out the chaff and wipe down your machine after roasting (once it has cooled down, of course).
  
  
• Make sure the beans are always moving. Increase the fan speed, stir, or whisk those beans… whatever you need to do to make sure they aren’t sitting still.
  
  
• Roast where you have lots of ventilation.
  
  
• Change your total roast time based on the ambient temperature. If it’s really cold out, you may need to roast longer to get the same results.
  
  
• After you roast, let your beans off-gas carbon dioxide for at least a few hours before storing.
  
  
• Put your freshly roasted beans in coffee bags with one-way gas valves. If you don’t have bags, any airtight container will suffice.

What you should NOT do…

• Add too much heat too early and scorch the beans.
  
  
• Rush the Maillard Reaction. This is where lots of flavor creation happens.
  
  
• Roast until the second crack or go over 20% development time. You might end up with bitter and burnt coffee. Unless you like oily Italian roasts, you don’t need to go past the second crack.
  
  
• Let your beans take a long time to cool down. Use colanders to help cool them more quickly, or buy a fan to help.
  
  
• Roast outside if it’s less than 60°F (60°C) outside. Your roast might take too long and come out tasting papery and bleh.
  
  
• Use too little or too many beans. Make sure you use the appropriate batch size for your machine. If the beans aren’t moving enough in your popcorn popper or roasting machine, try using less in your next batch so the fan can do its thing.
  
  
• Walk away from the roaster. Always stay with whatever device you are roasting on. There is always a risk of fire when roasting.

Pro Tip
If you want to take your roasting to the next level, consider using software like Artisan to track your temperature curves. I use a temperature probe connected to my computer so I can see how my roast is progressing. These software programs also track development time, duration of Maillard, etc. They are amazing for being able to replicate roasts once you get something you really like.

What to Expect: Home Roasting vs Professional Roasting

I think the number one thing that anyone getting into coffee roasting needs to remember is that your coffee will probably not be good for the first handful of batches. This isn’t a knock on you. 

Like any technical hobby, you have to start somewhere. If you have no knowledge of coffee roasting, you are starting at the very bottom. You will mess up and some roasts will end up in the trash. That’s okay.

Just be thankful you aren’t starting on a 5 kg machine, like I did. I wasted quite a few batches before anything came out decent!

Don’t give up, and check the tips above and resources online to troubleshoot any issues that arise. It may take a while before your coffee tastes as good as a professional roaster’s. Don’t set your expectations too high at the start - just have fun with it!

Another difference between home roasting and professional roasting is consistency. Roasters like myself rely heavily on temperature probes to measure air and bean temperature. We use ROR (rate over rise) curves to track tiny changes in real-time. 

When you run a coffee business, clients expect your bag of Natural Brazilian coffee from Alto Jequitibá to taste the same every time. After all, you wouldn't want your favorite store-bought beans to taste different every time.

When you roast your own coffee, you don’t need to worry about this as much. 

Without software and this equipment, it will be very difficult to closely replicate roasts, but you can add these things as you progress.

Are different types of beans easier to roast?

If you want to make things as easy as possible at the start, I recommend going with a washed coffee with a good sweetness and more basic flavor notes like chocolate and nuts.

Washed coffee usually goes through more post-harvest sorting than naturals, so your beans should be pretty equal in size and shape. There should be fewer defects, too.

This type of coffee bean can also endure more heat since they are denser than natural coffee beans. You don’t have to worry about scorching your beans as much, unlike naturals which require a more controlled, slower drying phase (2). 

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Frequently Asked Questions

Bottom Line

Roasting coffee at home is a rewarding and satisfying experience that allows you to always use fresh beans for the most flavorful coffee possible. 

With the step-by-step guide outlined in this article, beginners can confidently and successfully roast their own coffee beans at home. Remember to always start with high-quality, green coffee beans and experiment with different roasting levels and techniques to find your perfect cup of coffee. 

Whether you're a coffee aficionado or simply looking to explore the world of coffee roasting, the satisfaction of brewing and enjoying your own roasted coffee is unmatched. 

So, now that you know how to roast coffee beans at home, grab some, fire up the roaster, and savor the aroma and flavor of freshly roasted coffee.

Happy roasting!