The way in which coffee is roasted can have a profound effect its taste. Roast too quickly at too high a temperature, and you’ll scorch the exterior of the bean. Roast too slowly at too low a temperature, and you’ll sap the bean of its of flavour. Over the years, numerous roasting methods have been developed to address these challenges, all with the same objective: To transfer heat to the coffee bean, initiating a series of chemical reactions that prepare it for consumption. Most roasting methods include the following six phases:

1. Drying Cycle:
This is the first phase of the roasting process, when the temperature of the beans rises to
100 degrees centigrade. Also in this phase, the beans change from a bright green colour to
a pale yellow.

2. First Crack:
When the beans reach 160 degrees centigrade, complex chemical reactions begin to occur
causing a cracking sound.

3. Roast Initiation:
The beans swell to 140 – 160% of their initial size. Elements within the beans begin to
caramelise, giving the beans their brown colour.

4. Pause:
In this phase, the audible cracking ceases, but the reactions continue. The time of this
silence will depend on the amount of heat applied by the roaster.

5. Second Crack:
The progressive dehydration of the beans has made them brittle. As a result, more cracking
can be heard. It is at this stage that elements in the bean begin to carbonise, producing the
burnt characteristics of extremely dark roasts.

6. 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.