Roasting Coffee at Home? Get This Beginner's Guide!

Home roasting means you can drink fresh coffee anytime, anywhere, and try coffee from different origins. Although the learning curve is annoying at first, the satisfaction of learning how to roast and brew coffee makes it all worth it. But what equipment do you need? Which green beans do you use? When do you brew the coffee? Do you need an expensive roaster?

Why roast coffee at home?

There’s no better way to control your coffee than roasting it yourself. From origin to roast depth to flavor emphasis, you can customize it. However, this flexibility isn’t the only reason to roast at home.

Freshness is an important factor, and some green beans can be kept for up to a year after harvest without going out of date. However, roasted beans begin to lose their flavor and aroma after a few weeks. Purchasing small quantities of green beans for roasting on a weekly or even daily basis ensures that the coffee always remains fresh.

Best of all, green beans are much cheaper than roasted beans. Once you perfect your roasting technique and have the equipment, you may find yourself saving a lot of money in the long run.

Home roasting also broadens your coffee knowledge. You begin to understand what makes your favorite coffee taste so good, and how to change your roasting profile or buy different beans to bring out that. With practice, your taste buds will improve, and your ability to appreciate coffee will improve.

What happens to coffee beans during the roasting process?

Unroasted green coffee beans have a remarkable ability to retain water. Grinding and brewing them is out of the question. You also don’t want to take a sip of its distinct grassy taste. Roasting triggers all sorts of chemical reactions that produce even more flavor and aroma.

When green coffee beans are exposed to high temperatures, the moisture content begins to decrease. This is the first stage of roasting, also known as the drying stage. Shortly after this stage, the coffee beans begin to turn yellow. Many people call this the yellowing stage.

When the beans begin to darken, the so-called browning stage, the most important chemical reactions occur: the Maillard reaction, caramelization, and Strecker degradation. These produce many flavor and aroma compounds, including those that cause sweetness and fruity acidity.

The browning stage ends with the first crack, which is when the pressure inside the beans causes them to crack open. It can be identified by a series of popping sounds.

Eventually, all the water in the bean evaporates and reaches the second crack. The coffee steadily deepens and releases more carbon-like aromas. Most of the sugars are broken down, and as the roast progresses, the drink will become less tart and sweeter, while the acidity will increase. Light to medium roasts are usually between the first and second cracks, and dark roasts usually extend beyond second crack.

A Step-by-Step Guide to Home Roasting Coffee

1. Purchase green beans

At first, you may not know which coffee you like best. This is especially true if you usually drink blends. Try small batches until you find one you like. So it makes sense to purchase small sample packs, which usually include multiple regions.

If you want to learn how to roast coffee, you must know as much as possible about coffee. Even coffee from the same origin can vary greatly, especially in a large country or with different processing methods and varieties. So don't be shy and ask your boss for relevant information. This includes harvest dates, origins and micro-regions, green coffee characteristics (such as moisture content and size), and recommended roasting and brewing methods.

Mung beans will stay fresher and last longer if you store them in a cool, dry place at room temperature and away from direct sunlight.

2. Baking method

There are several home methods for roasting coffee, each with its own advantages and disadvantages. To choose between them, consider how much money you want to spend, how much coffee you want to roast, and how much control you want over the roasting variables.

Oven and skillet baking are inexpensive options. However, they are not recommended for beginners because they require a high level of skill to achieve an even bake. Controlling airflow is also an important part of baking, but it can be difficult using these methods.

Others can try roasting in a popcorn machine, which is easy to use. It is a good and simple device for roasting small quantities. If you want to roast larger quantities of coffee or have better control over the process, you need to buy a home coffee roaster. Now there are many home-use fool-proof roasters that are easy to operate, safe and reliable.

3. Arrange the baking space

Good ventilation is critical to both roasting quality and safety. Use exhaust fans, open windows, and consider roasting outside or in an open garage so that fumes released from the beans can escape.

There are a few more small pieces of equipment you'll need. A scale is a must, so you know exactly how much coffee to roast per batch. For those using a popcorn popper, a thermometer might also be helpful. Also prepare a set of silicone gloves for handling hot materials, a small fan for cooling, and a sieve to keep the beans aerated.

4. Roasted Coffee

If you buy a home roaster, the manual will tell you the different profiles. From the presets until you get used to the process. For a popcorn machine, it's even easier. Just make sure you don't fill it up too full and have somewhere for the chaff to escape.

Air roasters and popcorn makers usually take 8 to 12 minutes, and drum roasters may take 14 to 20 minutes. Just like cooking, the lower the temperature, the longer it will take.

Keeping the beans in constant motion is essential for an even roast. Popcorn machines and home roasters do this automatically; in a skillet, you'll need to stir the beans yourself, which is a rather labor-intensive process.

5. Cooling and storage

When the beans have reached the desired roasting effect, remove them from the fire and take them out quickly, otherwise the residual heat of the equipment can cause the roasting degree of the beans to change further. If you live in a cold environment, it is relatively easy to cool them quickly.

Once the roasted beans have reached room temperature, they can be stored. Heat, light, and oxidation are the enemies of fresh coffee. To avoid these problems, technically the best way is to store the coffee in a sealed foil-lined bag. If foil-lined bags and a heat sealer are not available, then storing the roasted coffee in an airtight container in a dark place is sufficient.

Don't brew the roasted beans right away, you need to let them degas first. Ideally, wait at least three days before brewing them. Some lightly roasted coffees (like Kenyan or Ethiopian) taste best two weeks after the roast date!

How to Avoid Common Home Baking Mistakes

While home coffee roasting is relatively easy, there are some easy mistakes that can spell disaster for your beans.

Don’t fix your roasting time, you may need to change it sometimes. For example, roasting outside may mean that your machine takes longer to preheat. Not adjusting for this may result in under-roasted beans.

Batch size can also affect roasting time and temperature. If you are roasting a very large batch, the beans may not absorb the heat evenly in the roaster. Or, you may be roasting too quickly so that not all the beans reach the proper level of browning.

Try balancing batch size and heat application until you get enough time for an even roast. If the roast time is long and the coffee is still uneven, try roasting less per batch.

Using the highest temperature setting to get a faster roasting time can result in burnt beans. Likewise, a thermometer measures the air temperature inside the roaster, but not the temperature of the beans themselves. Pay attention not only to the reading, but also to the color and aroma of the coffee, as well as the first and second cracks.

It is also important to clean the roaster. Inclusions and grease can accumulate, causing later coffee to have off-flavors or even catch fire. Keeping it clean will keep your coffee delicious. Mistakes can easily occur if you are distracted during the roasting process, so try not to leave the roaster.

How to Improve Your Home Baking

Becoming confident with the basics and wanting to learn more is where the fun begins.

If you are currently roasting in an oven or popcorn machine, try investing in a home roaster. There is no perfect roast, that’s the fun of it! Finding areas for improvement during each roast will make your roasting technique more and more perfect. Be consistent with the variables, try changing only one factor at a time to see what happens and how it affects the flavor and aroma of the coffee, and keep a roasting journal. The more experienced you are, the more you will understand what is happening during the roasting process and adapt to a wide variety of coffee roasts.

Finally, be realistic. “You will never roast a Colombian coffee to taste like Ethiopia or a Brazilian coffee to taste like Kenya. Coffee roasting is not alchemy!” Home roasting may seem daunting, but once you start you will find that it is a lot of fun. Have fun! Really connecting with and understanding our food will lead to a higher level of appreciation.