How does a coffee roaster work?

How does a coffee roaster work?

Coffee roasting is a fascinating process that is worth to get to know closer. Everything that happens inside the drum has an influence on the final product. Let’s take a closer look at the process of coffee roasting.  


How does a coffee roaster work? 


The process of coffee roasting includes several steps that cannot be ignored. Even though modern coffee roasting machines are packed with advanced technologies, the fundamental rules are always the same.  


In the beginning, the drum must be preheated before placing pale green coffee beans. Once the drum reached the desired temperature, you can pour the coffee beans into the drum. It is important to preheat this place because it will help to eliminate the moisture that still is in the raw product. When the coffee beans are dry, you need to observe their color which changes from light yellow to brown within 5-8 minutes. Along with the brown color, you will smell a fresh scent that is similar to popcorn that just popped.  


After around 7 minutes, the size of the coffee beans is being increased. It is happening because the heat and the air pressure form carbon dioxide and monoxide inside the coffee beans that become more voluminous. The temperature inside the coffee roaster reaches 200 or more degrees Celsius, which also increases the air pressure. It presses the walls of the coffee beans, and once it is high enough, the coffee beans start cracking. It has its own name – “first crack”. This is the breakthrough in your coffee roasting process. Not only the shade of brown color changed, but you certainly heard that characteristic sound – once again, it is similar to the popping corn seeds.  


The first crack is a moment, when the whole palette of aromas and flavors has opened. What does it mean? As a coffee roaster master, you need to be careful to not to “over-roast” your coffee beans. The color of the coffee beans changes rapidly within only four minutes, so watch closely, and end the process of coffee roasting, when you achieved the satisfying results. Dark roast needs more time than medium roast, but the line between those two roast types is thin. Fortunately, modern coffee roasting machines are precise, and they can control the temperature, the time, and the air flow. Once you discover your favorite recipe, you can save it and replay it next time.  


Now it is time for cooling. A cooling sieve is an important accessory which allows your coffee beans to cool down quickly, without losing the wonderful, fresh aromas. It is also worth to use a destoner, a device that separates coffee beans from stones or other potential objects that came with green coffee beans. Stones and metal pieces can appear even in high quality specialty coffees. Your coffee should rest for a couple of days to de-gas and to develop full-bodied flavors.  


Different stages of coffee roasting.


New technologies – does it do the job for you? 

It is true that modern coffee roasting machines can create fantastic roasts. Software programs are intuitive to use, they provide consistent roasts, and they are flexible. You can change the settings whenever it is needed, but on the other hand, you can use previously saved roast profiles, and replay them. Heating systems can control the temperature during each stage of the coffee roasting process. How does it work? There are several sensors that measure both bean and exhaust temperature. Besides that, powerful and often independent motors are responsible for effective roasting and cooling coffee. The list with all the conveniences is quite long, and they can be different depending on the brand, model etc.  


Coffee roaster machines on the today’s market can be fuel-powered or electric. The other option is more suitable for a small coffee roastery, whereas the fuel-powered machines are usually larger, and they are used for a bigger scale. The process of coffee roasting itself is based on the same rules, regardless of the power source – you will always hear the vivid sound of the first crack.  


Since you know how does a coffee roaster work, you can begin your own coffee-roasting adventure. Consider all the differences of coffee roasts, and prepare freshly roasted batches of coffee.