If you love coffee, you know there’s nothing better than a freshly brewed cup. But what really determines the freshness of your coffee? The roasting date is one of your best indicators. As soon as beans are roasted, they start to degrade. Therefore, it’s recommended to use those beans within 15-30 days of roasting.
Freshness is a big deal for coffee lovers, so the obvious step would be to roast coffee at home. It may sound hard but home roasting is completely achievable and a great way to have more control over the taste of your coffee.
Why Do Coffee Beans Need To Be Roasted?
When coffee beans are first separated from the fleshy part of the coffee cherry, they’re actually green. This is because they are technically the seeds of the cherry. Green coffee has a very grassy, plant-like taste and smells nothing like the coffee aroma you’re used to. Green coffee needs to be roasted to release and develop the flavour and aroma compounds that are essential to coffee.
Over 800 of these compounds get released by the heat of the roasting process. Clearly, roasting has a major impact on the flavour profile of your coffee. A light roast tastes very different from a dark roast and each level of roasting has its own taste and colour.
The Science Behind Home Roasting
Much like commercial roasting, home roasting is based on the principles of using heat as a catalyst for chemical reactions. These improve the flavour and aroma of green coffee beans.
There are three main stages in roasting: the drying stage, the yellowing or browning stage, and the final roasting or development stage.
The Drying Stage
The drying stage involves using heat to evaporate the moisture in the green coffee beans. The temperature is kept around 160° C to prevent burning while still being effective. This stage takes about 4-8 minutes.
The Browning Stage
Now the beans start to turn yellow and brown, known as the browning stage. This stage marks the release of aroma compounds. At this point, you’ll be able to smell the aroma of bread or hay. The browning happens due to the Maillard reaction, which involves the conversion of sugars and amino acids to flavour and aroma compounds.
The Final Roast & The First Crack
Finally, the heat within the beans reaches a critical point and the beans start to crack. The beans get darker and more aromatic. As you keep roasting, the coffee becomes more and more bitter and acidic. Light and medium roasts are finished around the first and second crack. Dark roasts, on the other hand, finish after the second crack.
What Do I Need For Home Roasting Coffee?
Home roasting can be incredibly simple, depending on the method you choose. Some prefer to roast in a pan, some use an oven, some even use popcorn makers, and some use special machines designed for home roasting.
You can often purchase green beans at local coffee shops and small roasteries. Online shops and communities are other great sources. If you don’t know exactly what you want, you can shop around online for small packs of green coffee to get started with. Online communities are very supportive with sourcing and giving you tips on home roasting.
- Pick your home roasting method
A pan or oven is your most cost-effective option. It may not be as precise as a dedicated roaster but it gets the job done. Many swear by popcorn makers for home roasting but keep in mind, those are designed for popcorn, not coffee and results vary by a large margin. A dedicated coffee roaster would be the best option, especially if you want to switch to home roasting completely.
- Have proper storage ready
Storing your home-roasted coffee properly will preserve its taste and aroma and improve the shelf life. Pick airtight containers, preferably glass or stainless steel, and keep the roasted beans in a dark and cool place.
Steps For Home Roasting
You have your green beans and you’re ready to start home roasting- but here are a few things to keep in mind before you start:
- You need to reach a temperature of 160°-250° C
- Always be stirring- don't let the beans settle for too long or it’ll burn
- Keep a timer handy so you don’t under or over-roast
- Pick a well-ventilated area so the smoke can escape
- Weigh your beans using a scale before starting and only pick an amount you’ll finish in 7-10 days
Once your beans are weighed, we can get started.
Roasting on a pan
Everyone has a pan, so this is the most accessible method. However, it’s tricky to get an even roast and may not be the best option for beginners.
- Ensure the area is well ventilated. This method produces a lot of smoke.
- Place your pan over medium heat. A gas stove is best because you can control the temperature better.
- Heat the pan to around 230° C
- Add your green coffee beans in a shallow layer and keep stirring
- You’ll hear the first crack after 4-5 minutes and the second crack around 6-7 minutes in.
- Wait 30 seconds after the first or second crack (depending on how dark you want the roast) and quickly remove the beans from heat. Cool it down in a colander, shaking to remove chaff and debris.
- Let the beans rest for 12 hours to allow gases to escape.
Roasting in an oven
Oven-roasting is a simple method, but it can get extremely smoky and is slower than other methods. Ventilation is key here or you’ll end up in a smoky haze.
- First, preheat your oven to 260° C.
- Spread your green beans evenly on an oven tray and place on the middle rack.
- The first crack happens about 5-7 minutes in. Removing them now will give you a light roast.
- The second crack indicates a medium roast. It’s recommended to wait 30-60 seconds after the second crack and then remove the beans from the oven.
- Quickly cool the beans, shaking and stirring them to remove the chaff (the thin outer skin of the coffee bean).
- Once again, leave the beans to rest for 12 hours.
Home roasting with a popcorn maker
Hot-air popcorn makers are a surprisingly good option for home roasting coffee. It’s simple and you don’t have to manually keep stirring the beans. The obvious drawback is that this appliance is made for popcorn so roasting coffee in it might damage it and shorten its life span.
- Preheat the machine as required.
- Put the beans into the machine but ensure it’s not too full. If you overfill it, the automatic agitation won’t work. Manually stir the beans to get the agitation started.
- The first crack happens around 3-5 minutes and the second follows at 6-8 minutes.
- Remove the chaff that collects in the machine spout
- Cool the beans in a colander and let rest for 12 hours.
Home roasting with a dedicated roaster
Home roasters are a great investment for coffee lovers. They can be expensive but ensure the safest and cleanest roasts.
- Simply measure out your beans and pour them into the machine. Follow the instructions for that particular model.
- After the desired roast level, remove and cool quickly before letting it rest.
Should You Start Home Roasting Coffee?
Home roasting can be a fun process and is a great way to learn more about coffee. It gives you the freshest and tastiest coffee while also allowing you to customize it exactly to your liking.
Home roasting allows you the freedom to choose how you consume your coffee. You can control every step to make a cup that is uniquely yours. The investment of time and effort only sweetens the cup further - after all, there’s joy in creating something with your own hands.
For those of you still considering whether or not to roast coffee yourself, try renting time at a co-working facility for coffee roasting. This concept is newer to the coffee world, and may not be available in every city just yet. Be sure to check your area for options.
The more you practice, the easier it gets and before you know it, you’ll be a pro roaster. So, take the leap and try out home roasting for yourself. It makes a world of a difference.