What are the main stages of coffee roasting?

by Joseph K. Clark

Roasting refers to the process of turning green coffee beans into brown ones. It can be made in various methods, which influences the flavor. The fundamentals of roasting and industrial roasting stages are here. Learn a lot of information on the coffee roasting process mentioned below.

Thermal shock

The green coffee is roasted in a roaster drum heated to 160 and 220 degrees Celsius. The coffee is subsequently subjected to a 150 to 200°C thermal shock. As a result, the roaster’s internal temperature drops for a few minutes as the bulk of green coffee at room temperature forces it to reach the lowest point of roughly 80-90°C. As a result, the bean is the one who cools the drum.


The heat transmission is reversed at this low point, and the cooking process begins. The coffee then begins to retain heat, and progressively heat the water within it, ultimately evaporating. As the water migrates to the bean’s surface, the green color intensifies, vegetal odors of cut grass emerge, ambient humidity rises, and the bean begins to inflate due to the increased internal pressure. The grain then dries significantly, lasting at least until the first crack appears.

The rise in temperature

The drying and heating of the coffee go as intended, and the Maillard reaction, which is found in foods, produces the first compounds. The beans swell and change color from straw yellow to creamy orange. Complex scents emerge, including bread, yeast, straw, beer, and foie gras, while gases like carbon dioxide develop and travel outwards.

coffee roasting


Caramelization begins around 170°C. The sugars are broken down, the grain turns dark and marbled, carbon dioxide generation rises, increasing internal pressure, and fragrances of roasted, grilled, caramelized, and dried fruits emerge.

The aromatic maximum

The coffee roasters in Melbourne will help the grains to become brown and veined with channels. The aromatic maximum is found between 180 and 200 °C. And the silvery layer dissociates, signaling the first crack.

The first crack

It happens when the temperature reaches 205 °C. The grains, which have now lost all of their water, release some carbon dioxide at once. Their volume doubles, their silvery coating is blown out, and their core groove deepens.

The most important part of the roasting process

The coffee roasters in Melbourne will help in the essential phase of development. The beans will brown, bulge, open in the middle, and bring the oils to the surface in less than three minutes. The acidity, followed by the scents, the body, and eventually, the bitterness, develop in waves. The roaster can only select when the coffee should be taken out of the drum to stop cooking. This could happen right after, during, or a few minutes after the first crack.

cooled in a tank with cold air circulation. The coffee is wetted by sprinkling after a specific amount, similar to how vegetables are iced in restaurants to preserve them crisp, colorful, and ready to use.

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