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.
Roasting coffee is a transformative process that alters the chemical and physical characteristics of beans. Through roasting, the green coffee beans undergo a taste transformation, resulting in the distinct flavors associated with coffee. Roasting is an art form, and there are numerous roasting styles practiced worldwide, each with its unique approach. In this blog, we will provide a comprehensive overview of the roasting process and guide you in roasting your own beans.
To begin, it is essential to understand your roaster machine. The classic drum roaster, which we manufacture, is the most prevalent and effective type in the industry. Drum roasters operate on the principle of a rotating cylindrical drum. The drums are heated either by gas or electric burners. Once the drum reaches the optimal temperature, we pour the beans into it. Our drums require a pre-heat period of 2-4 minutes before the roasting process begins, and the actual roasting takes approximately 8-12 minutes. During this time, the beans undergo various stages: green, yellow, steam, first crack, development, second crack, and cooling.
Green: This represents the raw form of coffee beans. The color may vary slightly depending on the bean’s quality and the environment in which the coffee is grown.
Yellow: When the beans are introduced into the hot drum, their color starts to change within the first 2-3 minutes. It is crucial to start monitoring the color at this stage.
Steam: As the temperature rises above 120 degrees Celsius, the beans undergo color, flavor, and aroma changes. The beans transition from yellow to brown during this stage. The Maillard reaction occurs, wherein the interaction between sugar and amino acids is activated by heat, resulting in the coffee’s distinctive taste. Continuous monitoring of the beans is recommended.
First Crack: This signifies that the beans have reached a medium roast, typically a City roast. Towards the end of the browning stage, moisture trapped within the beans transforms from liquid to gas, creating pressure that is then released with a sound resembling popcorn popping. The first crack can cause the beans to double in size as their inner structure expands.
Development: The coffee beans become browner, and the surface becomes smoother. This stage is where aroma compounds develop, defining the coffee’s key characteristics such as acidity, sweetness, and body. The development stage allows for experimentation with various variables, including roast length, darkness, and increments in between. Careful monitoring is crucial during this stage, as just a matter of 30 seconds can result in a completely different coffee flavor.
Second Crack: If the roast continues, the coffee may enter a second crack. This crack produces a softer sound compared to the first crack. Roasting too deep into the second crack can mask the stronger and more distinct flavors of the beans. Close attention must be paid during this stage, as the beans’ character rapidly changes. Prolonged roasting at this stage may even lead to burning.
Cooling: It is important to ensure that your roaster has an efficient cooling mechanism. We employ Bonfiglioli motors for cooling. After roasting, the coffee should be cooled rapidly to reach room temperature. Swift cooling is essential, as an extended cooling period may result in a dull taste.
By understanding the various stages of the roasting process, you can embark on an exciting journey of roasting your own coffee beans.