Coffee Bean Roasting: What Gases Are Released?

Coffee bean roasting is one of the important steps in making coffee. During the heat treatment process, various gases are released. These gases not only affect the flavor and aroma of coffee, but also play an important guiding role in the entire roasting process.

First, as the coffee beans begin to roast, they release moisture. This is because the moisture inside the beans begins to evaporate at high temperatures. As the temperature rises, the moisture gradually evaporates from the beans and enters the air as steam. This stage is often called the "first crack" because it produces a popping sound when the moisture evaporates rapidly.

Next, during the roasting process, which takes place at higher temperatures, the coffee beans release carbon dioxide (CO2). CO2 is produced by heating carbonates (present in the green coffee beans) at high temperatures. The amount of CO2 released depends on factors such as original storage conditions, time and processing methods.

In addition, other volatile substances may be released in the later stages or during deep roasting. These substances include acidic compounds, aldehydes and ketones. Their release usually brings special aroma and flavor to coffee.

It is important to note that the gases released during the roasting process have an important impact on the quality of coffee. On the one hand, the presence of gases such as moisture and carbon dioxide inside the beans will affect heat conduction, thereby affecting the accuracy of temperature control during the roasting process. On the other hand, these volatile substances are also one of the important indicators for evaluating coffee quality.