The Beginners Guide to Roasting Coffee

We’re a specialty coffee roaster based in Austin TX. This isn't a blog post on how we roast our coffee - oh no! This blog post is more of an introduction to roasting coffee, or the basics of roasting coffee at home if you will. If you’re a newbie coffee roaster, if you’ve never roasted before, or you just want to know what the hell coffee roasting is all about, then this blog article is for you. So here it is, a most fascinating blog article about the basics of how to roast coffee at home. 

Roasting coffee is as easy as you want to make it. So is cooking steak. Or it’s as hard as you want to make it! Anyone can heat up green coffee, but doing it well is a whole other thing. Turn the oven on or buy a popcorn cooker and you’ll be able to turn hard green coffee into soluble brown coffee beans ready for the grinder. But to do it to the level demanded of us in the specialty coffee world, takes time, patience, and skill. Trust us, it took us years! There's a long journey of learning to take between your first attempt at roasting coffee at home, until you're in charge of 25lb batches on the real thing. 

To start, you have to understand a little bit of science (yes, science is real) and have a small budget to play with. To be realistic, the learning curve, the equipment costs and the smell usually puts most people off at the very first hurdle. However, if you persist, you can be the master of your own cup of coffee. Roast, brew and enjoy your own cup of morning joy. Oh imagine that... the romance is real! 

But why would you roast your own coffee?

1. It saves you money - buying green coffee is cheaper than roasted coffee. If you drink a lot or have a huge coffee drinking household, this might make sense financially. 
2. Freshness - roasted coffee loses flavor quickly, green coffee stays fresh for 1- 2 years depending on how it’s stored. Just roast some when you need it.
3. Roast your coffee just how you like it. Want a dark roast on Monday and a light roast on Tuesday? Just roast it however you want. You're the boss!
4. You just love coffee and want to geek out in your spare time! Admit it, the coffee bean has enticed you and want to know more. The journey, the origin, the roasting science… it’s a puzzle you want to piece together. Go buy some green beans and roast it up coffee friend, and you’ll have a lot of fun as well as learn a lot along the way!

Step 1 - Buy a coffee roaster 

You need to ask yourself these three questions before you start googling “best home coffee roaster”. 

How serious are you taking this? 
How much money do you want to spend on your coffee roaster?
How much coffee do you want to be able to roast in one go? 

With this in mind, the more you spend on anything, the better it is. This applies to your coffee beans as well as your desired roaster of choice. But there's value to working your way up, and learning the hard way! I say start with the basic tools before you get to the fun techie stuff. 

Cheapest Home Coffee Roasters

Let’s start with the cheapest, the basic of all basic home coffee roasters, the inexpensive oven, skillet or popcorn maker. They will cook your green beans so you can grind them and brew them, yes, but they lack any reliable consistency. An even roast and a good amount of airflow will be extremely hard to achieve due to the basic nature of these instruments. That being said, these are easily accessible and you can have a lot of fun when you’re a newbie coffee roaster. If you try it and realize this isn't the life for you, then you haven't wasted thousands of dollars to work it out. We’d highly recommend this method to start with, and if you’re still intrigued, upgrade to a bigger and more sophisticated machine. Start basic, make mistakes, then move on up if your heart leads you that way! 

Home Coffee Roasters

The step up from here is to buy a dedicated coffee roaster. One that’s safe for your home and one that’s designed to actually roast coffee beans. Fresh Roast, Behmor, KALDI and Hottop all offer easily accessible models ranging from $150 up to $1000. They will give you a handful of variables that can be adjusted and will instantly yield much better results than your frying pan. 

The Best Home Coffee Roasters

If you’re looking to put a little bit of money behind your home coffee roasting hobby, and go for gold, then I’d recommend you look at the Atilio Bullet and Ikawa Home Roaster. They are small yet extremely accurate with a number of variables to play around with. Measuring your roasting profiles online via an app will give you greater control and endless opportunities to perfect your coffee roasting theories. 

Wanna go big? 

If you’re looking to get into larger quantities, then you’ll need to really think about how much coffee you want to roast. At this point, you may be looking at commercial machines that need professional installation. Are you looking for an airflow or drum roaster? How many presets, variables and control adjustments do you want? Quality comes at a price and having an all singing all dancing coffee roaster at home costs money. Before you drop some money, start cheap, make some mistakes, then do your research, and then splurge! 

Before you buy a coffee roaster… 

Think about ventilation. Even the smallest of roasters kicks out a delish aroma that lurks in your garage for weeks. Will your partner be understanding enough in the long run? Is your spare bedroom really the smartest place to have extremely hot equipment that releases smoke? 

Now you've got some form of coffee roasting equipment, you’ll need to buy some green coffee to roast. 

Step 2 - How to buy green coffee

What is green coffee? 

If you don’t know where coffee comes from, first check out our Growing and Processing blog posts. This will explain where green coffee comes from and how it turns from a cherry on a coffee plant into what is called green coffee beans.  

The green coffee bean is grown in the country of origin and shipped to the country where it will be roasted. Roasted coffee degrades in flavor much faster than green coffee so roasting usually takes place where the coffee will be brewed and enjoyed. Green coffee beans are small and hard, cannot be digested and are not soluble. Roasting turns these hard green beans into something that is soluble when ground. 

Where can I buy green coffee beans? 

We suggest going to the home of home roasters, Sweet Maria’s to buy some green coffee. You can buy small lots of varying quality and you can buy a bunch of different varieties from all over the world. Buy some and experiment your heart away. As you get more confident and know what you want, you may find other sources to buy your coffee from in larger quantities.  

Learn about where your coffee comes from, how it was processed, how it should taste. This will help your roasting style. When we source our own coffees we know where they come from, and pay more than FairTrade prices for a superior product. If there’s no info on your coffee, it’s probably just commercially grown and purchased. The farmer isn’t paid well and the quality will not be there.

Rule of thumb, you can't polish a turd. Buy cheap coffee, it'll taste like cheap coffee, however good you are at roasting!

How to store green coffee beans at home

Once you have purchased your green beans, you’ll need to ship them. Watch out for costs, green beans are heavy! You’ll want to store them away safely - in a cool, dry place at room temperature, away from direct sunlight and moisture. 

Step 3 - Roasting coffee beans at home 

Green, unroasted coffee beans have a significant amount of water retention, about 10% - 13%. It would be impossible to grind and brew them without roasting them. The magic of roasting causes chemical reactions which then releases delicious flavors and aromas from the bean. 

Heating the beans at high temperatures means the moisture content drops, and the green beans start to turn yellow. This is referred to as the yellowing stage or color change, and some pleasant aromas will start to be released. 

After a few minutes, the beans gradually start to get darker, closer to brown in color. Then we get the first crack. Like the sound of popcorn popping. Small pops rather than loud cracking. The beans get darker. The aromas and reactions intensify in the bean. 

During this browning stage is when the most important chemical reactions happen: the Maillard reaction, caramelization, and Strecker degradation. These create many of the flavor and aroma compounds, including those responsible for sweetness and fruity acidity.

If you want a more bitter and smoky flavor to your coffee, keep roasting! The second crack signifies a darker roasted coffee. The moisture has evaporated and coffee becomes even darker releasing carbon-like aromas. The sugars are breaking down and the acidity will diminish the longer you leave your coffee in the roaster. But you’ll lose sweetness and some of the pleasant flavors unique to your coffees origin. 

Light to medium roasts finish somewhere between first and second crack. Dark roasts typically finish after the second crack. Your personal preference dictates what is best, after all, you’re going to be drinking it afterwards, so roast it how you like!

Cooling your coffee beans 

Once you’ve reached your ideal roast development, the beans will need to be released and cooled straight away. Some roasters have this part of the roast sussed out, with a vented cooling tray. If you’re roasting on a skillet, you’ll need to prepare for the cooling stage yourself. Once your coffee has reached room temperature, you’ll need to store your beans away safely. 

Step 4 - Tasting freshly roasted coffee 

All your effort and hard work into roasting your coffee at home culminates to this very moment. The brewing and tasting part! Gases will be released from your beans as soon as they start to cool. If you brewed your coffee beans straight away, they will taste extremely smokey, even with a light roasted coffee. Therefore, cupping your roasted coffee should happen between 12-36 hours of the roast. Cupping is the universal practice used around the world to taste test coffee. It’s a sensory experience of sniffing and slurping coffee with a spoon. If you’re brewing your coffee to be enjoyed as a beverage as either espresso or filter coffee, the ideal time to enjoy your coffee will be anywhere from 4 days to 28 days after the roast date. Storing them in a dry environment, away from oxygen, heat, cold and moisture will keep your beans fresher for longer. 

My final thoughts on how to roast coffee at home

My recommendation to you, while you’re keeping it small, is to experiment, experiment, experiment! Use the same coffee and try different temperatures, roast times, dark, light, medium ... then taste test and try again. Use the SCAA Flavor Wheel and cupping sheets to help improve your palette and get you dialed into your coffees. Taste test with friends and push each other to name flavors. Roasting coffee at home is an experiment, don’t expect to suddenly work it all out over night, it's a journey. If you start with cheap green beans, and a rusty ol’ skillet, don’t expect miracles! But it’s a good place to start learning. Spend more as you go along and see your results improve. But most of all, have fun out there folks! And be safe!