Coffee that is consumed has been roasted, somehow. The methods have varied, to be sure. In fact, heating coffee in a pan was common until well into the 20th century. Today, most coffees are roasted commercially. Here too, there are several different approaches. Our discussion will focus upon our approach.
First, we employ a drum roasting machine, manufactured in the United States by Diedrich Manufacturing of Sandpoint Idaho. Drum roasters are the tool of choice for specialty coffee roasting since they are affordable and provide the roaster/artisan with full control of the roasting process.
In modern specialty coffee roasting, the roaster seeks to apply heat to green coffee beans in a manner that brings out the unique properties of a coffee variety. Our drum roaster provides us with three types of heat for use in the process. First, there is the radiant heat from the infra-red burners fueled by natural gas. This is applied to the rotating drum in which the green coffee beans are placed.
Second, as the drum is heated, it transfers some of that heat directly by contact to the beans within. This is conductive heat. Finally, we use convective heat, much like the convective ovens in many kitchens today. Heated air is brought into the roasting chamber in different quantities at different times during the roast. This heated air encircles the bean in the drum and transfers its heat to the bean.
“Micro-roasted” refers to coffee roasting processes in which the green beans are roasted in small batches to exact specifications so that the roasting can be fine-tuned for the specific bean, from batch to batch. The process is a craft tended by an artisan rather than a machine. Micro-roasted coffee is considered by many to be the best tasting coffee available on the retail market. The processes employed are designed to bring out the best of any coffee variety. The task of the roaster/artisan is to employ his/her skills, experience and senses in deciding how much of which type of heat to apply at what points in the roasting process for how long.