Once the beans are roasted, they need to be cooled immediately to avoid changes in quality and aroma.
The roasted coffee is cooled by air and water. Cooling time should not take more than a maximum of five minutes.
Ambient air is passed through roasted coffee beans either in the drum or in a separate cooling unit. Therefore, bean temperature is dropped to ambient temperature immediately.
Water quench cooling
The roasted coffee is cooled by spraying a small amount of water, either in the drum or in a separate cooling unit. Bean temperature is dropped to ambient temperate immediately.
Advantages and disadvantages of cooling methods
Air-cooled coffee beans do not contain extra moisture. A longer time is required for staling, and the rate of bean wastage is low.
Coffee beans cooled by water contain moisture. Staling time is shorter but water cooling is effective on regaining the aroma loss occurred during roasting. Also, the structure of the cooling water may contribute to various aromas.