What are the stages of coffee roasting?

Roasting is a precise exercise in thermodynamics. A roaster begins with green coffee, which is dense, pale, and grassy. The first phase, the **drying phase**, is all about removing the moisture trapped within the bean. This stage is crucial; if the heat is applied too aggressively, the outside will burn before the inside is properly dehydrated, leading to uneven results.

As the temperature rises, the coffee enters the **Maillard reaction**, a complex chemical process where amino acids and reducing sugars interact to create hundreds of aromatic compounds. This is where the coffee turns from green to yellow, and then to a light brown. During this stage, the roaster’s skill in managing the "Rate of Rise" curve becomes vital, as this is where the core structure of the flavor is built.

The transition toward the finish is marked by the **"first crack."** This is an audible sound, similar to popcorn popping, caused by the release of steam and carbon dioxide as the bean structure expands. Once the first crack occurs, the coffee is technically drinkable, but the final stage, **development**, is where the roaster decides the profile. A shorter development time will highlight bright acidity and origin characteristics, while a longer development time will smooth out the edges, increasing body and sweetness at the expense of those delicate, bright notes.

In practice, these stages are what distinguish a roaster’s style. A "light roast" is often stopped shortly after the first crack, preserving the unique character of the variety and its terroir. A "dark roast" pushes the coffee deep into the development phase, creating the characteristic notes of chocolate, nuts, and roast-derived bitterness. Understanding this sequence changes how you look at the roast level on your coffee bag; you are essentially reading the roaster’s decision-making process at the very end of that development phase.