The measurement and adjustment of the heated air moving past coffee beans during the roasting process. In most modern roasters, the coffee roasts primarily through convection – the beans are roasted by the hot air moving around them – and many machines offer a variety of airflow settings to give operators control over the speed at which that air moves.
Airflow plays an important role in the roasting process of coffee beans. It helps to evenly distribute heat throughout the roaster and to ensure that the beans are heated consistently, which is crucial for achieving a uniform roast. It’s also important for maintaining the volatile oils of the beans, ensuring they preserve all their best characteristics.
During roasting, the beans are heated to high temperatures, which causes a number of chemical reactions to occur, including the release of gases and moisture. Airflow helps to remove these gases and moisture from the roaster, which prevents the beans from becoming too moist and helps to promote an even roast.
Airflow also helps to control the temperature inside the roaster. In traditional drum roasters, the airflow is used to cool the beans after they have been roasted to the desired level, which stops the roasting process and preserves the flavour and aroma of the coffee.
The airflow can also be used to control the rate of the roast. By adjusting the airflow, the roast master can control the rate of heat transfer to the beans and affect the rate of development of the roast. This allows them to achieve a specific roast profile and to create a desired flavour profile for the coffee.
Overall, airflow plays a critical role in the roasting process, by controlling the temperature, moisture and gases, which affect the final flavour and quality of the coffee.
Also see:
This thread on home-barista.com: How Does Airflow Affect the Roast
Patent for a device controlling airflow in a home coffee roasting machine.
This study: The effect of air flow in coffee roasting for antioxidant activity and total polyphenol content.
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