Roasting a batch of coffee beans in a roaster for small amounts, comprises supplying unroasted coffee beans in batches to a vertically aligned roasting chamber and then again removing from the roasting chamber after roasting

摘要

The method comprises supplying unroasted coffee beans in batches to a vertically aligned roasting chamber and then again removing from the roasting chamber after roasting. The roasting process is carried out by hot air flowing through the roasting chamber and is controlled by a programmable control unit, where the temperature of the hot air and the time period of the roasting process are detected. The value of the initial volume flow rate of the hot air and the time period of the roasting process are selected by the initial volume flow rate independent of the temperature of the hot air. The method comprises supplying unroasted coffee beans in batches to a vertically aligned roasting chamber and then again removing from the roasting chamber after roasting. The roasting process is carried out by hot air flowing through the roasting chamber and is controlled by a programmable control unit, where the temperature of the hot air and the time period of the roasting process are detected. The value of the initial volume flow rate of the hot air and the time period of the roasting process are selected by the initial volume flow rate independent of the temperature of the hot air. After the flow of the selected time period, the value of the volume flow rate is taperedly controlled up to the end of the roasting process. The initial volume flow rate is constant up to the flow of the selected time period. After the flow of the selected time period, the value of the volume flow rate is reduced to a second low volume flow rate value and in the further flow of the roasting, the value of the volume flow rate drops from the second volume flow rate value up to a third volume flow rate value at the end of the roasting. The third volume flow rate value of 50% corresponds to the initial value of the volume flow rate. The value of the second volume flow rate is selected in dependent of the temperature of the hot air of the initial volume flow rate. The temperature of the hot air is 260[deg] C, and is independent of the type and condition of the coffee beans and/or the desired roasting effect. The volume flow rate is controlled by adjusting an operating frequency of a side channel compressor producing the volume flow rate. The operating frequency is 60 Hz with the initial volume flow rate and is reduced to 30 Hz at the end of the roasting. The temperature of the coffee beans is detected. The temperature and/or the volume flow rate of the hot air are controllable, so that a selected limit value of the temperature of the coffee beans are not exceeded during the roasting, where the limit value is 280[deg] C.