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Why Coffee Roasting Requires Ducting

During the roasting procedure beans are heated up to 260° Celsius or 500° Fahrenheit and transform from bright green to pale yellow as they dry into the final stages of dark shades of brown and even black (depending on the choice of taste profile). The heating method used to roast coffee beans produces dust and chaff from the skin of the beans, as well as, CO2, steam, vaporized oils and other gas emissions that must be vented.

When the roasting has been completed, coffee beans are sent through a cooling process where they are stirred and blasted with chilled air. In this step, dust extraction is utilized to remove chaff and other particulates. At times, a batch of beans may be misted with water to expedite cooling, this method carries away smoke, odor, and steam also requiring venting.

The last stage in the coffee roasting process is destoning which separates any wastes that were not previously removed from the batch. The most important pollutant to be collected during this process is chaff.