Coffee roasting is a chemical process by which aromatics, acids and other flavor components are created, balanced and/or or altered to augment the flavor, acidity, aftertaste and body of the coffee.
- Drying Cycle: In the first phase of the roasting process, the temperature of the beans rises to 212 degrees Fahrenheit, and the bean color changes from a bright green to a pale yellow.
- First Crack: When the beans reach 320 degrees Fahrenheit, complex chemical reactions begin to occur, causing a cracking sound.
- Roast Initiation: The beans swell to 140160 percent of their initial size. Elements within the beans begin to caramelize, giving the beans their brown color.
- Pause: In this phase, the audible cracking ceases, but the chemical reactions continue. The time of this silent phase will depend on the amount of heat applied by the roaster.
- Second Crack: The dehydration of the beans has made them brittle, so now more cracking can be heard. Also, elements in the beans now begin to carbonize, producing the burnt characteristics of extremely dark roasts.
- Stopping the Roast: Once the optimal amount of roasting time has elapsed, the beans must be cooled quickly. This is usually accomplished by introducing large amounts of cool air or water.