During traditional long-time drum roasting, coffee beans are roasted in small batches at 180 - 240 degrees Celsius. The roasting time is very long compared to industrial roasters and lasts 15 - 20 minutes.
Traditional drum roasting not only removes much unwanted bitterness, it also provides significantly better development of flavor and aromas.
With industrial roasters, coffee beans are exposed to very high temperatures of up to 1000 degrees Celsius in a very short time, often only 1 - 3 minutes.
This means the bean is brown on the outside but not well roasted on the inside. Do you know the bitter aftertaste? The burning sensation in your throat or stomach? Maybe you should try a different coffee.
Tip: Let your coffee cool completely and then test the taste. With poorly roasted coffee, you can clearly taste the unwanted bitterness which can also upset the stomach.
Traditional drum roasting is much more expensive than industrial roasting. For one thing, it takes much longer to roast coffee beans in traditional drum roasters, but there are other economic reasons.
During roasting, coffee beans lose a lot of moisture, which affects the final weight. Traditional drum roasting has a roasting loss of about 15-20% and industrial roasting of about 5-7%.
If you roast 100 kg in a drum roaster, you end up with about 80 - 85 kg of roasted coffee beans. With the industrial roaster, you get about 93 - 95 kg of roasted coffee beans from 100 kg of raw coffee beans.
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