What Happens During Roasting?

Transforming Green to Brown

Coffee roasting is where science meets craft. A pale, grassy green bean enters the roaster and emerges as the aromatic, complex brown bean we know. During those 8-15 minutes, over 1,000 chemical compounds are created or transformed.

Key Phases of Roasting

Drying Phase (0-5 min)

Green beans contain about 10-12% moisture. The first phase drives off this water. Beans turn from green to pale yellow and smell grassy or bread-like. Temperature: approximately 100-160°C.

Maillard Reaction (5-8 min)

The Maillard reaction — the same chemistry that browns bread and seared steak — begins. Amino acids and sugars react to create hundreds of flavor and aroma compounds. Beans turn golden brown, and the familiar coffee scent develops.

First Crack (8-10 min)

Pressure from steam and CO2 builds inside the bean until it audibly cracks — similar to popcorn popping. This marks the transition to a proper light roast. The cell structure expands and oils begin migrating outward.

Development Phase

After first crack, the roaster controls how long and how far development continues. This is where the roast profile is truly defined — balancing acidity, sweetness, body, and bitterness.

Second Crack (if reached)

A quieter, more rapid crackling indicates the bean's cell structure is breaking down further. This is dark roast territory — oils appear on the surface, and roast flavors begin to dominate origin character.

Caramelization & Degassing

Sugars within the bean caramelize, creating sweetness and body. After roasting, beans release CO2 for days — which is why fresh roasted coffee needs to degas for 24-72 hours before reaching optimal flavor.

At Röstschmiede, every roast is guided by careful profiling — monitoring temperature curves, airflow, and timing to bring out each coffee's best qualities while preserving its unique origin character.