Coffee Roasting Carried Out Different Temperature in Stages

Is coffee roasting carried out at a constant temperature? If not, what are the temperatures at each stage? Generally, coffee roasting is divided into the following stages with different temperatures:

Preheating stage

• The temperature is usually around 130℃-150℃. In this stage, the green coffee beans are evenly heated to prepare for subsequent roasting, and at the same time, some moisture in the green coffee beans is removed.

Dehydration stage

• The temperature gradually rises to 150℃-175℃. During this stage, a large amount of moisture in the green coffee beans evaporates, the color starts to gradually darken, and the volume of the coffee beans will slightly expand.

First crack stage

• The temperature is approximately 185℃-205℃. At this time, the coffee beans will experience the first crack, producing a sound similar to that of popcorn popping. This marks the beginning of changes in the internal structure of the coffee beans, the caramelization of sugars, and the gradual formation of flavor compounds.

Development stage

• The period from the end of the first crack to just before the second crack is the development stage, with a temperature of around 205℃-220℃. This stage is crucial for adjusting the flavor of the coffee, and the roaster will control the roasting time and temperature according to the desired flavor.

Second crack stage

• When the temperature reaches around 225℃-235℃, the coffee beans will experience the second crack. At this time, the color of the coffee beans is already very dark, oil begins to seep out on the surface, and the aroma becomes more intense. However, if the roasting continues, the coffee beans are likely to become burnt.