A roaster is a machine that people use to roast coffee beans. The basic process of roasting coffee bean involves heating the raw beans in a drum or rotating oven with heated air inside. Once the beans are roasted, they are cooled and then ground for brewing. The fluid flow produced by the rotation action of an agitator in a drum can also be used to impart greater flavor when comparing this method with other methods involving no agitation such as sound/shear energy from steam jets. The temperature determines the degree of roast, cooking time, and color of the roasted beans. These can vary through degrees Lighter-to-Darker or Sweet-toOlive, depending on how much time he material spends in the so-called "roasting zone."
Coffee roasters can produce up to 180 kilograms (400 lb; 170 oz) per hour, which boils down around 12,000 pounds of green coffee beans per day at capacity plus storage needed for aging stock.