Roasting · 8 min read
The journey from green coffee seed to the aromatic, complex bean in your grinder is one of the most remarkable transformations in the culinary world. Roasting is where potential becomes flavor, where the hundreds of chemical precursors locked inside a dense, grassy-smelling seed are unleashed through carefully controlled applications of heat.
At its core, coffee roasting is a series of chemical reactions driven by temperature and time. The first major milestone is the Maillard reaction, which begins around 150 degrees Celsius. Named after the French chemist Louis-Camille Maillard, this reaction between amino acids and reducing sugars produces hundreds of flavor compounds — the same reaction responsible for the crust on bread, the sear on a steak, and the deep amber of a well-made roux. In coffee, the Maillard reaction generates the nutty, caramel, and chocolate notes that form the backbone of most roast profiles.
Following the Maillard reaction comes caramelization, where sugars break down and reform into new compounds. This is where sweetness develops — but push too far and those sugars carbonize, producing the bitter, ashy flavors associated with over-roasted coffee. The art of roasting lies in navigating this narrow corridor between underdevelopment and overextraction.
The concept of first crack is pivotal. Occurring around 196 degrees Celsius, this is the moment when steam pressure inside the bean causes it to fracture audibly. First crack marks the boundary of light roast territory. Beans pulled shortly after first crack retain the most origin character: floral, fruity, tea-like qualities that reflect terroir, varietal, and processing. Push further toward second crack and you enter medium-dark to dark roast territory, where roast character dominates and origin nuances recede.
Modern specialty roasting has been revolutionized by data. Software like Cropster and Artisan allows roasters to log every variable and reproduce profiles with scientific consistency. Yet the best roasters will tell you that data is a guide, not a gospel. The roaster's palate remains the ultimate instrument.