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Roast Your Own Green Coffee Beans At Home: Heres How.

Understanding the roasting process broadens your appreciation for the art and the science that goes into pouring the perfect cup of coffee. Home roasting also ensures that your coffee is as fresh as possible, and the roast is as light or dark as you prefer.

We’re strong advocates for home roasting - we love it! We’ve seen countless people intending to try it just once, only to become home roasting addicts. It’s a passion for lifelong learning with never ending surprises and satisfaction. Enjoy the best tasting coffee in your home by following our simple guide. We cover the various methods, their pro’s and con’s and explore which one is best for you.

"What will I need to get started?"

The great thing about roasting green coffee beans at home is there’s virtually no barrier to entry. Depending on your chosen method and what you’ve already got at home you can get started roasting today!

4 Preferred Methods to Roast Coffee at Home

Diving into the world of home roasting is incredibly easy. Choose the method you feel most comfortable with from the following:

  1. Roast in a pan/grill
  2. Roast in an oven
  3. Roast in a popcorn popper
  4. Roast in a purpose-built home coffee roaster

Roasting in a pan or oven is the cheapest way to get fresh beans. But for producing the best possible results we recommend that you choose either a popcorn machine or a purpose-built coffee roaster for their simplicity and consistency.

However, the price jump from a popcorn machine to a coffee roasting machine can be massive. Popcorn machines can be picked up brand new from as little as $20, whereas a high-quality home roaster can be around $500, skyrocketing upwards from there. Cheaper machines can be around $150 but are often of inferior quality and may break down sooner.

If you're serious about roasting your own coffee beans, it's worthwhile investing your money in a machine that will stand the test of time!

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A Word of Caution

  • Popcorn machines are designed for popcorn. Using a popcorn machine to roast your coffee will void the warranty, and the machine may break after a few months of regular roasting. Additionally, not all popcorn machines are suited to roasting beans.
  • Ensure your popcorn machine heats from the sides. DO NOT roast coffee in a machine that heats from the bottom! This will not only result in a weak and uneven roast, but the collection of chaff can ignite and cause house fires.
  • Always clean out all chaff between roasts, and NEVER LEAVE YOUR POPCORN MACHINE UNATTENDED!

Buy a dedicated roaster if it’s within your budget. Your resulting roast is often better than it is from a popcorn machine, and these are purpose built so will usually last far longer than a popcorn machine ever will.

The one method we don't cover in this guide is microwave roasting. It is possible to roast beans this way, but the poor results and inconsistencies that come with it make it impossible for us to recommend this method. Use one of our four other methods if you’re going to roast at home.

The process is simple, and if you follow our guide, you will be guaranteed a fantastic roast no matter your chosen method.

Understanding the Roasting Process

In this article, we’ve provided you with step-by-step instructions for each of the four home methods. Your exact approach to roasting will vary depending on your chosen method.

But what never changes is the process:

  1. Beans get hot
  2. Beans get roasted
  3. Beans get cool
  4. Beans get delicious
Coffee Bean Stages During Roast

It’s a simple process with some necessary steps to note along the way to guarantee great results. These important steps hold true for every method.

Let's take a quick look at what happens during and after roasting so that you know what's going on while the magic is happening:

Roasting

  • Temperature: 350F to 500F is the widely accepted temperature range. This varies depending on the method you’re using.
  • Agitation: Your beans can never rest and roast! Constant stirring ensures an even distribution of heat, and thus an even roast.
  • First Crack: After 3 to 5 minutes the beans will produce an audible crack. This crack indicates that your beans are lightly roasted and ideal for white coffee. This the minimum amount of time required to produce roasted beans. Continue roasting and agitating for darker roasts.
  • Second Crack: After a few more minutes another crack is heard. This crack indicates a medium roast. A few more minutes of roasting and your beans will be burnt and unusable. Experiment with times to find your favorite roast.
  • Tip: We usually wait roughly 30 seconds after hearing the second crack.
  • Cool Down: Transfer beans to a metal colander or baking paper to cool. Use two metal colanders (plastic can melt). Shake and transfer your roasted beans between colanders. This cools the beans quickly and removes the chaff.
    Spread evenly over baking paper to substitute for a metal colander. This method is not as effective.
  • Remove Chaff: Chaff is the dried husk of the coffee bean. It is very messy. Cool your beans down outside or in the sink to reduce clean-up

It is one of those things that you'll get the feel (and eye) for with practice. This video is a good start:

Post-Roast and Chemistry

When you’re roasting coffee beans, you are creating an awesome chemical transformation - the Maillard reaction.

Over 800 compounds are transformed (​1​​​) from the boring, flavorless compounds present in the raw beans into the delectably delicious and aromatic compounds found in roasted beans.

In the very early stages of roasting colored plant compounds such as chlorophyll, anthocyanins, etc begin to decompose [...] accompanied with subtle changes in aroma from grassy to more toast/popcorn notes. - Coffee Chemistry

This is why raw beans smell and taste nothing like roasted beans. The compounds in the beans are waiting to be transformed!

Roasted beans release gas (CO2): This continues for weeks (​2​​​) after roasting. Why should you care?

  • ​CO2 helps to naturally preserve roasted beans by displacing oxygen
  • Oxidation ruins beans. They become stale
  • Too much CO2 in coffee beans creates too much crema (a bad thing)
  • Not enough CO2 creates stale tasting coffee (also a bad thing)

De-Gas: Wait 12 hours before sealing in a container (Allow the initial Co2 to escape)

  • Sealing newly roasted beans in storage too early will lead to CO2 pressurization. This can pop the top off your container, potentially damaging it.
  • Coffee beans that contain too much CO2 will result in an undesirable flavor. Give your beans a chance to de-gas!
  • Opinions differ. From a few hours to a few days. In our experience, we’ve found 12 hours to be a good rule of thumb. Your experience might prove otherwise - do what works for you

Grinding and Storing after Roasting

  • Wait 24 Hours before you Grind & Brew. Beans need a day to mature and reach full-bodied flavor
  • Store in airtight container: Keep beans fresh and use within seven days
  • Coffee is always best when it’s fresh. After more than one week, your roasted beans will begin to turn stale as oxidation does its thing

Getting Started

White Coffee Beans

All right – enough with the science side of things, you’re here to learn how to roast your own beans at home, so follow these steps and you’ll be roasting like a pro in no time…

1. Buy Green Beans

It all starts with the beans, which technically speaking are seeds. Fresh beans are green. Once dried, they become several shades lighter. Once roasted they are completely transformed, becoming the beautiful and inviting rich shades of brown that we’re used to seeing.

Excellent coffee is all about consistency. Choose beans that are uniform in size and color: this ensures an even, consistent roast and flavor. Getting these two elements correct - color and size - is vital to avoid producing coffee with an inconsistent and unfavorable flavor (​3​​​​​​).

When coffee is roasted consistently, baristas and other consumers know what they’re dealing with and can trust they’ll get the same cup every time. - Perfect Daily Grind

2. Roasting

This is where the magic happens. Choose from one of the following four methods and follow our guide to producing the freshest, most delicious beans you’ve ever tasted!

We'll show you how to roast with a pan, an oven, a popcorn maker and a home roaster below.​

Roasting Beans in a Grill or Pan

Roasting coffee beans in a cast-iron skillet

Everyone has a pan or grill lying around, which means this method is very popular among the home coffee roasting community. 

You'll find plenty of how-to videos on YouTube, however, be wary of who you take advice from - many DIY roasters tend to overcook their beans using this method!

NOTE: Do not use a coated/non-stick pan. Doing so will negatively impact the flavor.

PROS

  • Fast & convenient
  • No need for additional purchases

CONS

  • Difficult to get the correct temperature
  • Very smoky
What You'll Need
  • Green coffee beans
  • Thick pan (cast iron/steel/uncoated)
  • Hot plate/Grill (gas is preferred)
  • Colander x 2 (metal)
  • Oven mitts
  • Wooden spoon
  • Air-tight storage container
Method
  1. Maximize ventilation. Turn on the exhaust fan and open the windows. It’s going to get smoky and smelly (the good kind of smelly, the bad kind of smoky). Grilling outside is the preferred option to avoid overpowering your fellow occupants
  2. Place a thick pan on medium heat. Around 450F will normally do the trick
    • Getting the temperature right the first time can be difficult. Experiment to find the best heat
    • A gas stove/grill will make attaining and adjusting the temperature much easier
  3. Add a shallow layer of beans to the pan. Enough so you can stir with ease
  4. Keep Stirring. Never let the beans rest. Ensure they’re heated evenly
  5. Listen for the first crack after 4-5 minutes. Your beans are now a light roast
  6. Listen for the second crack after 6-7 minutes. A few minutes later the beans will crack for a second time indicating a medium roast. Roasting for much longer will result in burnt beans. Most people, us included, will wait roughly 30 seconds after this second crack before removing from the heat
  7. Dump beans into colander. Stir and shake. Cool them down ASAP. Do this in the sink or outside to avoid the inevitable chaffy mess. Wear heatproof mitts! Everything will be very hot
  8. Leave beans exposed for 12 hours to de-gas

Note: If you're aiming for French roast coffee, this method is not the best choice. Keep reading.


Roasting Coffee in the Oven

Another popular DIY home coffee roasting method involves your oven, but be warned: you'll need ventilation as it will get smoky!

NOTE: If your oven is the kind that blows a gale, do not use it. The chaff will get blown around leaving you with a great chaffy mess to clean up.

PROS

  • No need for additional purchases

CONS

  • Slower than other methods
  • Difficult to get a perfect roast
  • Very smoky
What You'll Need
  • Green coffee beans
  • Perforated oven tray (regular trays will also work)
  • An oven
  • Colander x 2 (metal)
  • Heatproof mitts
  • Air-tight storage container
Method
  1. Pre-Heat oven to 500F: Crank it up to 11. Temperature will vary for different beans and different ovens. Start at 500F and experiment up and down from here to find what works for you
  2. Open everything but the oven door: Things are going to get smoky. Maximize ventilation
  3. Spread beans over perforated tray: One layer deep only. Do not stack them!
    • A perforated tray will produce the best results. Just make sure that the tray you’re using doesn’t allow beans to slip between the holes
    • Beans expand during roasting and will get stuck in any holes that are large enough to accommodate a green bean
    • Don’t have a perforated tray? Try your luck with a regular oven tray and place a sheet of baking paper under the beans. Give them a shake or two as they roast
  4. Place on tray on middle shelf: The middle of the oven provides the most consistent temperature
  5. Listen for the first "crack" after 5-7 minutes: Your beans are now lightly roasted. Roasting for much longer will result in burnt beans.
  6. Listen for the second "crack": The beans are now a medium roast. Most people, us included, will wait roughly 60 seconds after this second crack before taking out of the oven
  7. Transfer to a colander. Stir and Shake: Cool them down ASAP. Do this in the sink or outside to avoid the inevitable chaffy mess. Wear heatproof mitts the whole time
  8. Leave beans exposed for 12 hours to vent CO2.

Roasting Coffee in a Popcorn Machine

Popcorn machines are made for popcorn. Certain types, however - especially a hot-air popcorn popper - can do a great job at roasting coffee beans. Just make sure you read our safety concerns about roasting with a popcorn machine before getting started.

NOTE: You must use a machine with side vented heat to avoid burning and to ensure rotation.

PROS

  • Simple
  • Automatically agitate/rotate beans
  • Easy to get a perfect roast

CONS

  • Not built for roasting coffee
  • Some machines will break after a few roasts
  • Price is not an indication of the longevity of machines used for roasting
What You'll Need
  • Beans
  • Popcorn machine with side vented heat
  • Wooden spoon
  • Colander x 2 (metal)
  • Heatproof mitts
  • Air-tight storage container
Method
  1. Ventilate! Roast near an open window, or outside, if possible, to avoid filling your house with smokes and smells
  2. Pre-heat machine. 30 seconds, depending on the model
  3. Measure ½ cup of beans. Drop into the machine. Ensure the beans can rotate
    • Popcorn machines should agitate the beans. If there’s no agitation you’ve probably filled the machine too full
    • Using the same quantity of beans as the machines’ recommended quantity of corn kernels is a great starting point
  4. Assist the agitation. Use a wooden spatula or spoon and encourage the beans to start moving
    • One you’ve got some consistent movement place the lid on
    • Keep an eye on this for the whole roast and lend a helping hand if you must
    • Use the handle if your spoon is too big
  5. Collect chaff in a large bowl. Catch all the chaff that will come out of the machine’s spout. As soon as the lid is back, on get your bowl in position to avoid a massive clean-up
  6. Listen for the first "crack" at 3-5 minutes. You’ve achieved a light roast!
  7. Listen for the second "crack" at 6-8 minutes. Your roast is at medium level! Keep roasting for another 30 - 60 seconds to get your roast darker. Much longer and your beans will begin to burn
  8. Transfer between colanders to cool the beans. Use oven mitts when handling the machine and colanders. Things are going to be sweltering. Do this outside or over your sink to avoid a chaffy mess
  9. Allow 12 hours for the beans to vent their CO2

Roasting Coffee in a Home Coffee Roasting Machine

If you're serious about roasting, chances are you'll end up buying a good home roaster. They are getting cheaper, and they do a much better job of roasting than some of the hacks above.

A good home coffee roaster will be much more consistent in the roast levels it produces. Once you find your sweet spot, consistency is the key to long-term coffee happiness.

Two we can recommend are the FreshRoast sr540 (best for beginners, small batch roasting) or the Behmor 5400 1600 drum roaster (for more experienced roasters looking to roast a pound at a time)

PROS

  • Purpose built and long lasting
  • Simple to use and clean

CONS

  • More expensive than other options
  • Bulkier than other options
What You'll Need
  • Beans
  • Coffee roasting machine
  • Heatproof mitts
  • Optional: colander x 2
Method
  1. Ventilation. All roasting methods, including dedicated machines, will produce lots of smoke
  2. Turn machine on. Add beans. Follow the manufacturer's instructions. Machines are similar, but requirements differ
  3. Monitor the entire roasting process. Many machines claim full automation. However, with all of the variables (bean size/type, ambient temperature, age of machine, etc.) roasting times can still vary
  4. Listen for the first and second "cracks." The first indicates a light roast. The second indicates medium. Finish roasting once the beans have reached your desired roast
  5. Transfer between colanders to cool the beans: Your machine may have it’s own cooling process. If not, cool them down ASAP
    • Do this in the sink or outside to avoid the inevitable chaffy mess.
    • Wear oven mitts for this process
  6. Allow 12 hours for the beans to vent CO2

3. Store them properly

When you buy pre-roasted beans, you’ll notice a little valve on the outside of the bag. This is a one-way valve that allows the built up CO2 to vent without letting oxygen in. This keeps the beans fresher for longer.

There are storage solutions you can buy that employ the same one-way valve system. There are even high-tech solutions that pressurize the container with an inert gas!

Regardless of your storage solution, space age or stone age, it needs to be airtight (4). It also must be kept cool and in the dark to ensure the flavors are preserved for as long as possible.

For something, a little different check out the wall mounted Zevro Indispensable SmartSpace Dry-Food Dispenser (below) that promises to be airtight and delivers roughly 1 ounce per turn.​

Zevro Food Dispenser

There’s also the BPA-free and military-grade Coffee Gator Coffee Container (below), which promises to keep your beans safe from "flavor destroyers".

Coffee Gator Canister

Fancy storage solutions are all well and good, and they may help to extend the life of your home roasted beans by a few more days. However, you can avoid purchasing anything extra simply by repurposing an old mason jar.

And if you haven’t got anything fit for purpose, grab something cheap like the stainless steel Friis 16-Ounce Coffee Vault:

Friis Coffee Vault

Regardless of how you end up storing your beans just remember:

  • Airtight
  • Opaque/Solid
  • Keep it Cool

VERDICT - Should You Roast Your Own Coffee At Home?

If you ask us, the answer is unequivocal yes.

 It’s not just a fun and rewarding experience, but it’s the only way to guarantee the freshest, tastiest beans while ensuring that you’re always drinking the roast you prefer: light, medium or dark - the choice is yours.

With virtually zero barriers to entry, you can begin roasting with whatever you already own, or make a few small purchases to get up and running. And now you know how to roast coffee beans from the comfort of your humble abode.

Wondering what's the best roast for each brew method? Check this article here.

Buying pre-roasted beans is still a good option. But with a little time and a small amount of effort, you can begin drinking the best coffee you’ve ever had!

What’s more, home roasted coffee makes an ideal gift for your coffee loving friends and family, providing they love coffee as much as you do.

So what do you think? Are you going to give roasting a go? Have you already tried? Leave us a comment and share your experiences. If you’ve followed our guide, we’d love to hear how you went, leave a comment below or visit our homepage.

Infographic: Roasting Coffee Beans At Home

Frequently Asked Questions

What do different roasts of coffee mean?

Different roasts of coffee mean how dark the coffee beans are roasted. Although you’re roasting to your own preference, rather than to the standards of a coffee roaster or coffee shop, it’s good to become familiar with different roasting levels so you can compare other roasters’ work to your own and hone your skills. Lighter roasts tend to retain the flavor of the beans, with notes of toasted grain as well as woody and sometimes fruity or floral notes, and typically roast only to the first crack. Darker roasts have more toasted flavors, with the darkest - Italian, Espresso, and French roasts - having a seared flavor like food on a charcoal grill. Here's a guide to different types of coffee roasts.

Which coffee roast is the strongest?

The strongest coffee roast depends on whether you’re considering flavor or caffeine. If you’re considering flavor, coffee roasted dark tends to have a very strong flavor, with more bitterness in the finish, while lighter roasts tend to have flavors of grain, wood, and sometimes fruit. If you’re considering caffeine, light roasted beans have more caffeine than dark roasted beans, but light beans are also heavier. If you brew your coffee by weight, there’s not much difference in caffeine between light and dark. If you brew by scoops, a lighter roast will have a very slight edge.

Is light or dark roast coffee better for you?

Light or dark roast coffee both have similar health advantages. Dark coffee has a slightly higher concentration of antioxidants, but if you’re roasting your own, you should roast it for the flavor you love. Having another cup of coffee will give you more antioxidants, too!



References

  1. Chemical Changes During Roasting. (n.d.). Retrieved July 5, 2019, from https://www.coffeechemistry.com/quality/roasting/chemical-changes-during-roasting

  2. CoffeeFAQ. (2017, January 08). Degassing/Storage. Retrieved July 5, 2019, from https://coffeefaq.com/degassingstorage/

  3. Fernando. (2019, March 14). A Guide To Achieving Consistency In Coffee Roasting. Retrieved July 5, 2019, from https://www.perfectdailygrind.com/2019/02/a-guide-to-achieving-consistency-in-coffee-roasting/

  4. National Coffee Association. (n.d.). Retrieved July 5, 2019, from https://www.ncausa.org/About-Coffee/How-to-Store-Coffee

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  • Alex
  • February 18, 2016
Alex
 

Alex is the Founder and Editor of Homegrounds.co. He is passionate about brewing amazing coffee at home, and teaching others to do the same.

Click Here to Leave a Comment Below 1 comments
Pratya Kanjanarat - September 1, 2018

After reading through this article, I decided to use a small oven to do roast my coffee bean (light roast, and medium roast) for my drip coffee. I found that it is so simple to do and I have been roasting coffee for my family on weekly basis.

Thanks for this nice article about coffee.

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