Channeling Julia

One of the essentials for roasting fine coffee is - the roaster! This week we are visiting Simple Pleasures Coffee Roasting Co. in San Francisco, who own a roaster with a 25lb capacity.

Today's coffee roasters were designed in the 19th century. The only changes made in recent designs are additions of an afterburner to reduce pollution and a safety control system to prevent overheating.

The design is simple - hot gases from the oven burners travel through a rotating drum and heat the beans. The operator controls the degree of roasting by varying the amount of time the beans stay in the roaster. There is a small window that shows the beans tumbling as the drum rotates. Next to it is a sampling device that collects about 1/2 cup of the beans so they can be removed, smelled and viewed by the operator. This sample is returned to the roaster after observation.

When the beans have reached the desired stage, a door in the front is opened and the beans spill out into the cooling pan. Air is blown through the beans to quickly cool them as a rotating paddle stirs the pan. Once cool, the beans are collected from the cooling pan and stored for later use.

The temperature inside the roaster is maintained at about 450°F. In cold weather it can take longer to preheat the oven, so the time required to produce a batch can vary - the operator must compensate for the weather as well as the condition of the beans (primarily moisture content) when they are loaded into the oven.

A small roaster is preferred when the operator wishes to roast frequently and rotate stock quickly. Large commercial coffee roasting facilities commonly use roasters with a capacity of 500lb or more that rely more on automation controls so the operator doesn't need to be as skilled.

Special thanks to Ahmed Riad and Simple Pleasures Coffee Roasting Co.