A device for use in a process for roasting coffee beans comprises measuring means (10) for performing measurements of an actual value of particulate matter emission from the coffee beans during a process of roasting the coffee beans, and controlling means (20) coupled to the measuring means (10) for receiving the outcome of the measurements from the measuring means (10), wherein the controlling means (20) are adapted to find a pattern of the particulate matter emission over time on the basis of the outcome of the measurements, to determine an actual roasting degree of the coffee beans on the basis of the pattern, and to determine and set at least one characteristic of the roasting process on the basis of the roasting degree.
