Coffee Roasting The Art and Science of Coffee Roasting Roasting is a chemical process that transforms the green bean into a delicate brown bean. At the same time, quality roasters are artisans who, over time, develop a style that highlights the characteristics of a coffee they prize.
Coffee roasting is a simultaneous process of destruction and creation.
Coffee beans are exposed to high heat in a chamber that rotates them to ensure balanced exposure to the roasting heat. The intense heat disrupts the molecular compounds and the woody structure of the beans and starches are broken down into simple sugars. Meanwhile, the moisture present in the unroasted bean evaporates at the temperature increases. This causes the bean to become lighter and less dense. This also causes internal pressure inside the bean to increase.