How to Roast Coffee Beans

Get Roasting Coffee Beans Yourself

how to roast coffee beans

coffee roast types

Thinking about roasting your own coffee beans at home instead of buying them already roasted?

Perhaps you’re a bit unsure of the DIY coffee bean roasting process.  Well push your fears aside because you’re now going to learn how to roast coffee beans.

There is a huge increase in places to buy green coffee beans (unroasted), whether online or at your local store.  Either way you’ll be spoilt for choice.

There are also many ways to roast them, so you could see your experimentation becoming quite a hobby.  Be warned, coffee roasting takes a bit of practice and patience to get right, but once you’ve mastered the art you won’t go back to buying from your supermarket.

Buying green coffee beans is also cheaper than buying vacuum packed already roasted beans.

Plus they stay fresher longer, from 6-12 months whereas roasted beans start to go stale within as little as 2 weeks.  So it makes sense to roast your own.

Follow this 4 step guide to roasting your own  coffee beans

1.  Choose your green coffee beans

Green coffee beans

 

 

 

 

 

 

If you’re going to roast your own coffee beans, then you’ve got the opportunity to create a roast that is unique to your taste as well as to your choice of roasting method.

You can buy green (unroasted) coffee beans, as well as organic coffee beans online or often at your local coffee-house. Selecting your own green coffee beans can be a great experience.

 

REMEMBER: if you purchase different coffee beans from the same continent, they will most likely share a similar flavor profile.

Hopefully the coffee roasting process chart will help you find beans suited to your palate and style of roasting.

2. Choose your home coffee roaster

With so many choices it’s easy to get confused and wonder which is the right one, or the right way of roasting.

First, consider the following 4 factors:

  • How dark do you want your coffee?
  • How much money have you got to spend on your new hobby?
  • Do you drink a lot?   Coffee we mean.
  • Do you want to use a more traditional DIY way of roasting, or would you prefer an automated roaster to do it all for you?

After you’ve factored in the above, you’ll then have a better idea of what you are looking for.

Automated home coffee roasting machines

There are two types of automated home coffee roasters: the drum style and the air roaster (aka a fluid bed roaster).

Drum roaster

As you probably guessed, a drum roaster rotates the coffee beans inside a metal cylindrical drum with a controllable heating element housed in the drum area.

Drum roasters are usually bigger than air roasters and they roast the beans more slowly, with roasting times in the region of 14-20 minutes. Nearly all commercial roasters that you see in coffee shops are drum roasters.

Pros:

  • great for developing a full-bodied roast.
  • offers the ability to control the temperature and the roasting profile.
  • easy to personalize your roast as well as replicate it.
  • able to roast larger quantities of coffee beans.

Cons:

  • tend to be larger than fluid bed roasters, so not ideal if you have a small kitchen area.
  • not suitable for darker roasts.
  • can be very expensive to buy.

Air/fluid bed roaster

An air roaster works in a similar way to a popcorn maker by forcing hot air onto the beans and roasting them whilst moving them around, giving a ‘fluid bed’ appearance.

Air roasters can roast a small batch of green coffee beans of 85-113 g (3-4 oz) in approximately 8-12 minutes.

Fluid bed roasted coffee is described as having ‘brighter’ flavors, meaning they feel lighter in the mouth and have less body.

Pros:

  • faster roasting times.
  • small by design, so they are ideal for smaller kitchen areas.
  • relatively inexpensive to buy.
  • easy to clean…always a bonus.

Cons:

  • less durable than a drum roaster.
  • can be affected by line voltage and ambient temperature, which may roast slower or faster making it a bit unpredictable.

Choosing an automated roaster is really a matter of choice as they both produce good results.  But you’re better off buying an entry level one to start with until you’re more confident in the art of coffee roasting.

On the other hand you might want to try your luck at manual DIY roasting before taking the plunge and buying an automated roaster, or you might just prefer a more hands on experience.

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Manual/DIY roasting

This method allows you to have more say in creating your own variety and style in coffee roasting, and can certainly be more interesting than using an automated coffee roaster. So here are some DIY ideas to think about for roasting coffee beans at home:

How to roast coffee beans in the oven

Probably not the best method for an even outcome, but it’s certainly one of the most accessible ways of roasting  your coffee beans.

Here’s the lowdown on what you need:

  • a perforated flat baking tray, such as a pizza tray…that’s it!

Now here’s what you need to do:

  • spread the coffee beans evenly over the tray in a single layer.
  • preheat the oven to 500⁰F (260⁰C).
  • pop the tray onto the middle rack of the oven and wait for approximately 6-7 minutes for the coffee beans to hit the first step of the roasting process, which is a crack sounding similar to popcorn cracking.
  • after the first crack keep an eye on the beans and remove from the oven when the beans reach a slightly paler color than the roast you’re after.
  • do not roast the beans by this method for any longer than 20 minutes.

Remember – beans continue to roast even after you’ve taken them out of the oven for cooling.  So make sure you don’t let them get to the color of the roast you want before taking them out the oven.

This method is best suited to making dark roasts for use in espresso coffee.

Pros:

  • you have all the equipment you need at home already, which saves you money.

Cons:

  • the roast could be uneven due to temperature fluctuations in the oven.

How to roast coffee beans using a pan roast/stove top

This is the oRoasting coffee beans using a wokld school way of roasting coffee beans and probably takes the most effort…..so be warned.

What you need:

  • a skillet, wok or cast iron pan with a lid or aluminium foil. If using a wok you need a wooden spoon.
  • oven thermometer.
  • metal sieve.
  • stove top….for obvious reasons.

Here’s what you do:

  • heat the skillet to 500⁰F (260⁰C) on the stove top, check it’s reached this temperature with the thermometer.
  • when at the right temperature put the beans into the skillet and cover with the lid or aluminium foil.  Be prepared to shake that pan for the entire time those beans are being roasted (usually for around 5 minutes).
  • if using a wok you will have to stir the coffee beans constantly with the wooden spoon.
    Be warned, if you stop shaking the skillet you will get an uneven roast.
  • the same applies here as with the oven method: remove the skillet from the heat when the coffee beans are a paler shade away from the roast you want.
  • tip the beans into the sieve so they can start to cool down.
  • Stir them around so they cool quicker and for the air flow to provide a more even roast.

Pros:

  • you’ve got the equipment to hand at home already, so no having to spend on expensive items.
  • you learn the basics and experience a traditional roasting method.

Cons:

  • it’s easy to burn the beans until you get the hang of it.
  • you might have a tired arm afterwards from all that shaking.
  • this method unfortunately usually produces a low cup quality.

How to roast coffee beans using a hot air popcorn maker

This method of roasting can be dangerous as you are using an appliance not specifically designed for roasting coffee beans.

However if you do want to give this a go, then please ensure you stick to the safety precautions and NEVER LEAVE THE MACHINE UNATTENDED.

Make sure the popper you buy is one that pushes air into the canister via side vents only. Do not choose a popper that pushes air through the bottom mesh as this can cause the chaff to ignite, and before you know it the popper’s on fire.

how to roast coffee beans using a popcorn machine

Roasting coffee beans using a popcorn machine

Air travelling through the side vents will blow the chaff up and out of the popper chute, so have a bowl ready to collect it.

What you need:

  • a hot air popcorn maker (see guidelines above).
  • metal sieve
  • thermometer (optional).

Here’s what you do:

  • put the green coffee beans, a similar amount to what the machine states for popcorn kernels into the popcorn maker.
  • after approximately 4 minutes you will hear the first crack of the 6 roasting stages.
  • shortly after the first crack turn the machine off.
  • place the roasted coffee beans into the sieve for cooling off.
  • move the sieve around to allow air to pass over and through the coffee beans to cool them down quicker.

Pros:

  • a more even roast and often better results than the other DIY methods of roasting.
  • quick and easy to use (provided you follow the machine’s instructions for use).
  • good for producing light to medium roasts.

Cons:

  • can only roast small batches at a time, approximately 3-4 oz.
  • you have to be extra cautious as the popcorn maker is not designed to be used as coffee roasting equipment.
  • going for darker roasts will probably shorten the lifespan of the machine.
  • if you are after a darker roast, the popper may not be the best choice as it can overheat if used for longer than it should be used for.

Now you’ve got some idea of how you can produce your own freshly roasted coffee at home using one of the methods above, you might like to know the process to getting fresh roasted coffee beans.

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3. The roasting process to getting the perfect cup

The roasting process follows a certain pattern that your coffee bean will go through, so it’s vital you watch so you can see, smell and hear the changes as they occur. This way, with practice, you’ll get a good idea of how you can create a roast that’s to your liking.

Keep notes on a record sheet of your attempts recording timings, beans used, etc, which will ultimately help you create your perfect roast.

The temperatures quoted are for guidelines only. Each roasting method reaches different temperatures at different times, so it’s advisable to use a thermo probe if you have one.

The following occurs whichever method of roasting you choose, whether it’s an automated coffee roaster or using one of the DIY methods.

Roasting process and stages chart

You’ve put your green coffee beans into whichever method of roasting equipment you’ve chosen, so the following table explains the processes coffee beans goes through and what to look for:

Roast levelFlavor & aromaSurfaceSoundKnown as
Light
bean temperature: 410-424ºF
210-225ºC
light bodied,
higher acidity,
bread-like aroma

slight smoke
dry, no oil,
light brown,
uneven surface.
first crack:
complete at 30-90 seconds after the end of the 1st crack.
Light city roast
Cinnamon
New England
Medium
bean temp:
425-455ºF
225-235ºC
sweeter and stronger than light roast,
more balanced in acidity & complexity,
increased smoke
no oil,
dry,
medium brown,
smooth.
right before 2nd crack.
90 seconds - 3 minutes after 1st crack ends.
Full City Roast
American regular
Breakfast
Dark
bean temp:
455ºF-475ºF
235-245ºC
more smoke,
burning smell
dark brown,
even color,
oil on surface,
brittle
Right after 2nd crack begins.
30-60 seconds into 2nd crack.
French roast
Vienna roast
Espresso
Italian
Continental
Black/brown to charcoal
Bean temp:
475ºF +
245ºC+
very bittervery dark brown to charcoal,
very oily
Don't go there!No flavors are left

 

Your coffee beans will go through various stages, starting with:

DRYING the green coffee beans start to turn a brownish yellow as they start to steam.  They may smell slightly grassy or smell of bread at this stage.

FIRST DEVELOPMENT the beans will now give off the aroma of coffee and they now begin to smoke as they turn a light brown.

FIRST CRACK this may take from 3-15 minutes to begin. They make a loud cracking or popping sound similar to the sound of popcorn popping. The first crack is much louder than the second and occurs when the fibers in the coffee bean split and begin to steam.

The crease in the bean fractures and the thin layer of skin covering it is now brown and flaky.

If the process is stopped at the first crack it is classed as underdeveloped as there hasn’t been enough time for the required chemical reactions to take place, so the flavor hasn’t been released, and you don’t want that.

Generally these Coffee bean color changes during roastingcoffees are less palatable and are known as Half roast or Cinnamon roast.

SECOND DEVELOPMENT occurs towards the end of the first crack and starts to produce a more palatable roast.

SECOND CRACK take notice of this crack and make sure you pay attention to timing as it begins 15 seconds to 2 minutes after the first crack ends.

The second crack is much quieter, similar in sound to crinkling paper or Rice Krispies popping in a bowl of milk.

It occurs approximately between 455-475ºF and there’s more smoke as the beans start to darken in color.

If the sound seems to be just one intense line of crackling then you might have the heat up too high and the beans will burn.

Remember, remove the beans just before they reach the color you want to achieve as they keep roasting after being removed from the heat.

Also keep in mind if you go much past the second crack you’ll end up with charcoal…..not a taste you want to experience.

Again, keeping a roast record is a great way to track timings and color of the roasts, and before you know it, you’ll be a master coffee roaster in your own home.

So you’ve got some fresh roasted coffee beans, it’s now time to cool them down to stop them cooking.

4. Cooling your fresh roasted coffee beans

The process of roasting has many stages as you know, and each stage is vital to the flavor development. It’s easy to put all the effort into getting these stages just right, that the cooling process can often be regarded as less important….not so.

Most modern home roasting machines have an inbuilt cooling system that will cool the beans to room temperature within 4 minutes.

Why within 4 minutes?

Well if it’s taking longer than 4 minutes to reach room temperature then you might end up with dried out beans that you are definitely not going to enjoy.

There’s also the matter of sweetness.  Sucrose is the primary sugar in coffee and it needs to be soluble when you pour hot water into it. If cooling is done too slowly the sugars in the coffee bean bind with its insoluble components.

So as you can see cooling to under the 4 minute mark provides a sweetness to the cup that makes for a far more enjoyable coffee.

So how do you cool those coffee beans down if you’ve manually roasted them?

You need:

  • nothing too technical really, just 2 metal (not plastic) colanders or pans….put them in the fridge 30 minutes prior to roasting.
  • oven gloves….please remember that the beans are going to be extremely hot so make sure you’ve got those oven gloves on.

Here’s what you do:

  • remove your freshly roasted coffee beans from the heat when they are nearing the color of the roast you want as they continue to roast after removal (sorry, I know we keep saying this…but it is important).
  • tip the coffee beans into one of the colanders and then keep pouring the beans from one colander to the other.
  • keep some distance between the two colanders as this allows air to pass over the beans cooling them down quicker.
  • whilst doing this, agitate the beans to help cooling further. If you can, do this outside so the chaff (skin around the coffee bean) that flakes off doesn’t end up floating all around your kitchen.
  • another option is to use an electric fan to blow air directly at the beans. If you use this method, whisk the coffee beans around the colander with a large spoon at the same time.

So there you have it, a pretty detailed guide on how to roast your own coffee beans. Once you’ve done it a couple of times, you’ll roast them yourself all the time.

WARNING at no time should you leave your coffee beans unattended when roasting them, whether that’s using an automated machine or you’re doing it manually. Always keep a close eye when roasting coffee beans at home.

Next: how to store coffee beans

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Sources:
infographic courtesy of http://en.ilovecoffee.jp/posts/view/177
Coffee beans roasting in a wok image: Dan Bollinger, Wikimedia Commons
Popcorn maker image: source: Chris g Collision, Flickr Creative Commons
More coffee roasting info: http://www.ncausa.org/About-Coffee/Coffee-Roasts-Guide

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