Roasting coffee is a transformation process that changes the chemical and physical shape of beans. The roasting process is what produces the characteristic flavors of coffee by causing the green coffee beans to change in taste. It is also like art. That’s why there is a lot of different roasting style in the world and none of them is wrong. In this blog, we will explain the basics of roasting and let you fire up some beans by yourself.
First, you need to examine your roaster machine. Classic drum roasters which we produce for you are the most common and the most effective roaster type in the roasting business. drum roasters are based on the principle of a cylindrical rotating drum. Drums are warmed by gas or an electric burner. When the drum is hot enough for the process we will pour the beans into it. Our drums need 2-4 minutes pre-heat before starting the roasting process and the roasting takes 8-12 mins. The beans will go through different processes which are green, yellow, steam, first crack, development, second crack, and cooling.
Green; Raw version of coffee beans. It might be a slightly different color that depends on the quality and environment in which coffee grows.
Yellow; When you pour your beans into the hot drum, in the first 2-3 minutes it starts to change color. At this moment you should start checking the color.
Steam; As the temperature rises above 120 degrees it causes changes in color, flavor, and aroma. Here we see the color of the beans evolve from yellow to brown. The Maillard reaction starts here where sugar and amino acids react to heat and externalize the taste of the coffee. We should keep checking the beans.
First Crack; means you’ve reached a medium, generally a City roast. Towards the end of the browning stage, moisture trapped within the beans changes from liquid to gas, and pressure builds up which is then released with a popcorn-like sound. This is called the first crack and can result in the beans doubling in size as their inner structure expands.
Development; The coffee bean becomes browner and the surface smoother. The development stage is where aroma compounds develop and the key characteristics of the coffee are defined, such as acidity, sweetness, and body. There are lots of variables to play with here – long, short, dark, light, and various increments in-between – and this stage requires careful monitoring as a matter of 30 seconds can result in a completely different tasting coffee.
Second Crack; If the roast continues long enough, coffee will go through a second crack. This is slightly softer sounding than 1st crack. Roasting too deep into the second crack will mask even the stronger and more distinctive flavors of your beans. It’s important to carefully monitor this stage of the roast as the character of the beans begins changing at a rapid rate; if left for too long, they may even burn…
Cooling; You should make sure that your roaster has a good cooling mechanism we have Bonfiglioli motors for cooling. After roasting, coffee will be cooled quickly down to about room temperature. It’s key to have this done quickly since longer cooling period may lead dull taste.