Roasting

Only during the first step in the roasting process does the coffee bean start to get its individual aroma. Factors such as temperature and length of roasting determine the taste and aroma (roast grade). The trick is to combine the correct temperature with the correct roasting time to optimize taste and aroma of the beans.

Before the coffee roaster was invented, beans were roasted in the classical way:

Beans were put into a drum and the drum was heated to 200o C. The drum was then shaken for 6-20 minutes. This important process was supervised personally by the roasting master, and frequent quality checks were made. At the end of the roasting, air was pumped through the drum to cool the beans.
This method was very time consuming and expensive, but produced the best aroma.

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Today, beans are roasted as quickly and cheaply as possible. The beans themselves are heated to 200-260oC, when air at 400-600oC is pumped through the drum. They are then cooled with water, which is not good for the aroma.
This kind of roasting is used by large corporations. It is possible with only machine work, faster, and cheaper. However, it compromises the coffee’s aroma.
During the roasting process, coffee beans lose about 20% of their weight. The beans also double in volume.