How do you roast coffee at home?

Reading time: 10 minutes
Author: Jarek
15 Jun 2023
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You should be warned at the outset - roasting coffee at home can lead to unforeseen results. We, in 2003, roasted our first green beans in a cast iron pan on a regular gas cooker, and today we run a roastery. In the United States, the home roasting movement has spawned a great many artisan roasters and, in the process, has been one of the forces pushing forward the development of specialty coffee. So it may be that today you are casually reading a blog post and in a few years we will meet at a roaster competition. If that is the case, so much the better! The text is long, but it will tell you all about how to start roasting coffee at home.

Palarnia kawy Braci Ziółkowskich, czyli od palenia w domu do rzemieślniczej palarni kawy
Ziółkowski Brothers Coffee Roastery

Why roast coffee at home?

You'll say it's a silly question - if you're reading this, you probably know all too well yourself why you want to start roasting coffee at home. But those expectations are worth talking about, because however beautiful and romantic, home roasting has its limitations.

Well, yes - roasting coffee at home will definitely allow you to:

- drink fresh coffee every day

- constantly experiment

- drink great espresso coffee

- make the perfect gift for friends - people love getting coffee that someone has roasted themselves at home

What will go wrong? First of all, it will be difficult for you to compete in quality with transfer coffeesand from top roasters. We're not saying it's impossible. The challenge is not only to roast the coffee brilliantly, but to then replicate the firing profile. Roasting beans for overflow is much more difficult than roasting for espresso. We have a much smaller margin for error, and everything plays out in a much shorter time. True repeatability in overflows requires a greater investment in equipment. But the lack of repeatability is not necessarily a disadvantage - by roasting coffee at home, we have much more room for experimentation than a professional roaster.

If that doesn't put you off, we can fire up nerd mode.

What it takes to start roasting coffee at home

The first and most obvious issue is the coffee roaster. It is around it that most home roasters' discussions revolve. And rightly so. Without it, you can't move.

Seed! Not the least of the issues. When we started in 2003 the availability of grain in retail quantities was meagre. Most companies started the conversation from a bag up. Today it is easier, but it will still be one of the main issues you will face.

Know-how. That is, knowing what to do to roast coffee well. Apparently, the internet is full of free content about roasting, but very often they contradict each other. What should you stick to?

Below, in a long-winded - well, difficult - way, we discuss all three of these issues.

Wypalanie kawy na domowej palarce patelniowej
Younger brother roasts coffee on a pan roaster

Cooker or coffee roaster

Our first coffee roasting set was based on a cast iron pan. We attached a crank to the glass lid to drive the three arms that constantly set the coffee in motion. We heated the pan over a gas burner, poured in the green coffee and turned the crank for a quarter of an hour, so that the beans were constantly in motion. Finally, we took the pan off the gas, poured the beans into a large sieve and cooled them in the wind.

The undeniable advantage of this solution is the price. If you have a brother-in-law who welds, you will be able to get by with less than a few hundred zloty. The disadvantage is the low level of control. Of course, by practising smoking you will find your gas setting to go from start to finish at a satisfactory rate. But never achieve the same two firings.

Chłodzenie kawy na wietrze po wypale w warunkach domowych
Refrigeration of the coffee on the filler

The second major drawback is airflow, or the flow of air through the coffee. Here it occurs to a minimal degree - the warm air travels upwards and escapes through the gaps between the pan and the lid. To some extent, the coffee suffocates in the fumes from the roasting process. Today's roasters - artisanal and industrial - rely on high airflow. This ensures that the flue gases are continuously discharged into the chimney and do not adversely affect the roasting process. On the pan, we improved the flue gas flow by replacing the glass lid with a steel lid with cut-out holes.

And believe us, the espresso from the pan came out really good.

Attention, coffee smoke!

An important digression: fumes are called that not by accident. At higher temperatures, coffee starts to smoke, and the darker you want to roast it, the more smoke will be created. A kilo of beans roasted in a pan, even with the windows open and the hood on, will fill the whole house with the smell of roasted coffee for a day with a hook. It's not unbearable, but it's definitely worth taking this factor into account. Especially if you don't live alone and the other household members are not as into coffee as you are.

A connection to the chimney is therefore useful. In a domestic setting, of course, this is not always easy. We know stories of home roasters who hooked up to the ventilation and then had problems with their neighbours.

So it is better to move out of the flat with smoking.

Do you have an attic, a garage, a spacious basement? Great! You can smoke outside during the season. In the worst case scenario, you can attach a spiro pipe to the smoker and thus lead the smoke outside the window. We've tested it - it works, not that much smoke comes back inside again. You just have to watch out for possible fire alarms.

For smaller cookers and smaller portions of green beans - say in the range of 50 to 100 grams - it is much simpler. The hood should be able to cope with this amount of smoke, and the impact on the air in the flat will certainly be less than if you are frying fish, for example.

Palenie kawy na patelni w plenerze
Coffee roasting in the open air

What to look out for when buying a home coffee roaster?

- size - how much coffee you can put in the oven at once and whether this is enough for your needs

- type of heating (electricity, gas)

- temperature probe - ideally there should be two, for the grain and for the flue gas

- Scale cyclone - small parchment scales fly out of the cooker along with the exhaust fumes, which are good to catch before they cause a fire.

- Coffee cooling - you can cool the coffee in a sieve, it is better to have a solution built into the roaster. The beans should reach room temperature within 4 minutes of pouring out of the roaster

- connection to roaster programmes (Artisan, Cropster) - not necessary, but they will give you an easy way to record firing data

Devices available on the market for amateur coffee roasting start at £1500-2000. There is no upper limit. If you want to start with something affordable before you throw yourself headlong into this adventure, we recommend a roaster Behmor 2000AB Plus. It costs around £2,000, works great for espresso, and we've also drunk very successful pour-overs roasted on it by two Silesian roasters.

For less than a dozen thousand you get Aillio Bullet. This is already a full-fledged 1 kilo roaster with good temperature sensors. It is quite common in Polish roasters as a test roaster and for roasting small batches of very expensive coffees.

In a similar price range lands Ikawa. It is a convection cooker, meaning that the smoking process takes place through a stream of hot air. Compared to the Aillio, it is much smaller - 50 and 100 gram versions are available. For that, it fits easily into a suitcase and you will take it on (almost) every trip. We're not sure if it's worth it, but as you can see, it is.

Próbka kawy po wypaleniu w piecu Ikawa
Coffee roasting with Ikawa roaster

Where does the grain for our home roaster come from?

In the beginning, it's not worth going crazy with quality. Even if you happen to catch a geisha fermented for 1,500 hours over which Diego Samuel Bermudez did the competition dance and pulled off an SCA 95 knockout, maybe don't let it be your first home firing. The chance that your first home-burned beans won't work out for you is non-zero, to say the least. As a starter, it's worth buying a solid Colombia Supremo with a score in the range of 83-84. It will be ideal for getting to know and befriend the roaster. Roast it for a while to get used to the heat properties of the cooker and only then take on the more expensive beans.

Spoiler - firings spoil even the most experienced roasters. The more expensive the coffee in the roaster, the more it hurts.

OK, but where do you get the grain from? The problem with home smoking used to be that the grain was available in 60kg bags. That's a lot. Anyone who consumes a kilo of coffee a month doesn't want to stock up for five years ahead. For one thing, how many times can you drink the same coffee. Two, coffee ages and loses some of its properties over time. Instead, it develops defects - in particular the wet-wood aroma, which clearly signals a coffee that is long past its prime.

Zielone ziarno z Etiopii przygotowane do wypału
Green beans before firing

Where to buy green coffee?

The market for specilata roasters has led producers and importers to package green beans in smaller packages. Today, it is possible to buy 20-kg bags, 30-kg bags and sometimes even 10-kg boxes. For those wondering how to roast coffee at home, however, this is still too much. So what to do?

Fortunately, there are now companies that sell coffee in smaller quantities. In Poland, this is Mega Coffee in Gdynia (from 1 kilo, commercial grade and specialty coffees on offer), in Europe you can take advantage of the offer Falcon Micro (specialty in 1 and 5 kilo packs). Technical note - for green coffee, do not stop at what is hanging on the website. It is best to write an email right away describing your need.

Green coffee is all about relationship.

Finally, you can contact any of the Polish coffee roasters to ask if they will resell you coffee in small quantities. Every roaster has some leftovers that no longer fit into the normal production cycle and they will be happy to share them with you. Ziolkowski Brothers is certainly one of those roasters.

Know-how, or a short lesson in coffee roasting

There's the oven, there's the grain. What's next? To say that this is where the stairs begin is to say nothing. The internet is full of free education about coffee roasting. But what good is that if most of this so-called 'knowledge' is worthless, and you can easily find contradictory answers to every question. How do you know that a very popular educational video teaches you how to spoil your coffee rather than roast it well? Or that a major roasting guru builds his system on an unproven and rather bogus parameter?

We know the pain, because we ourselves used to be stuck in front of a screen wondering how to filter through all the information noise.

Of course, it would be impossible for us to summarise for you here the entire smoking philosophy of the Ziolkowski brothers (which is, of course, the only correct philosophy. Instead, we have some simple advice to get you started.

Wypalanie kawy przy użyciu pieca Ikawa
Coffee roasting in an Ikawa cooker

A note in brackets is needed here. We write this text as if there is one best way to roast coffee. We have the conviction that this is the case. We taste coffee, roasted the way we roast it. But taste, taste - these are individual matters. In Turkey, we value coffee that, in objective terms of sensory evaluation, has the so-called Rio defect, i.e. a sweet, musty aroma of mould or iodine. We have met roasters who roast their coffee for a minimum of thirty minutes, we do not exceed fourteen. Consumers are different, their needs are also different.

Coffee can therefore be roasted in a variety of ways and is likely to be enjoyed by someone.

So we'll modify our post - what we propose below is a simple, complete system for approaching coffee roasting that allows you to get results quickly and start your own experiments. We don't know of a better system for getting started.

Three simple rules to start smoking at home

Firstly - you need to trust someone. In our opinion, a great source of very easy to apply knowledge about smoking is Coffee Mind Academy. It is probably the only free resource available that is backed up by scientific research. One of their webinars will give you more than hours of scrolling. And it's worth quelling the urge to look elsewhere for knowledge. Focus on what Morten Münchow says, master your cooker and only then go further.

Secondly - think of smoking a bit as a science experiment. Suppose your equipment allows you to change a lot of parameters. In an ideal world, you could modulate the strength of the heat, the speed of the airflow, the rotation of the drum. And then there are the things left up to you - the amount of coffee, the temperature of the roaster at which you pour the coffee, etc. The temptation to change everything at once is huge. It's also the source of most failures.

If you spin all the sliders at once, you will never know why the coffee was tasty once and not at all.

To be able to say anything seriously, only one variable needs to be changed each time. Suspect that something is wrong with the infeed temperature? Roast your coffee two or three times, doing everything the same, but changing just this one parameter. Observe if anything has changed. If nothing has changed, it may be something else. Continue experimenting.

Palarka patelniowa z wyciętymi otworami zwiększającymi przepływ powietrza
Pan burner with cut-outs to increase airflow

Thirdly - if you are investing in not the cheapest roaster and not the cheapest beans you want to roast under overflow, spend a little more and buy a colourimeter. This is a relatively simple device that allows you to measure the extent to which your coffee is roasted after grinding. It measures the colour of the coffee on a numerical scale. And it is a real game changer. With the colourimeter, you have the opportunity to compare individual roasts not only in terms of taste (our sensor is a great measuring device, but quite unreliable by the way), but also in terms of colour. Two coffees can be similar to the eye and the colorimeter can show a big difference. In our experience, this one device significantly speeds up the process of learning to roast - especially learning to roast repetitively.

Finally, or simply start roasting coffee at home

If you have made it all the way here, we assume that you are highly motivated and really want to try roasting coffee at home. And if so, our advice - do it. As soon as possible, even if you don't have the best equipment and outstanding coffee. Watching the beans turn from green to brown and tasting your roasts is a great experience. Once you've experienced it, the desire to get better will itself pull you further.

Photos: Tomasz Tolloczko

Author: Jarek
15 Jun 2023
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