What happens during the roasting process
The transformation of soft-green raw coffee beans into marvellous brown, aromatic and tasty coffee is the high art of roasting.
In the drum roaster the beans are continually moved. The water vaporises in the hot airflow. The pressure in the bean rises and it gains volume.
With the easily audible ‘First Crack’ water vapour escapes and the silver skin pops off.
The sugar in the bean reacts with the proteins. The results are flavours and colouring agents.