page_title: Coffee roasting
section_title: Equipment
hierarchical_section_title: Coffee roasting / Equipment
caption_attribution_description: English: DIEDRIC infrared drum coffee roaster. Dansk: Infrarød tromle kafferister.
context_page_description: Roasting coffee transforms the chemical and physical properties of green coffee beans into roasted coffee products. The roasting process is what produces the characteristic flavor of coffee by causing the green coffee beans to change in taste. Unroasted beans contain similar if not higher levels of acids, protein, sugars, and caffeine as those that have been roasted, but lack the taste of roasted coffee beans due to the Maillard and other chemical reactions that occur during roasting.
  The vast majority of coffee is roasted commercially on a large scale, but small-scale commercial roasting has grown significantly with the trend toward "single-origin" coffees served at specialty shops. Some coffee drinkers even roast coffee at home as a hobby in order to both experiment with the flavor profile of the beans and ensure the freshest possible roast.
  The first recorded implements for roasting coffee beans were thin pans made from metal or porcelain, used in the 15th century in the Ottoman Empire and Greater Persia. In the 19th century, various patents were awarded in the U.S. and Europe for commercial roasters, to allow for large batches of coffee.
context_section_description: The most common roasting machines are of two basic types: drum and hot-air, although there are others including packed-bed, tangential and centrifugal roasters. Roasters can operate in either batch or continuous modes.  Home roasters are also available.
  Drum machines consist of horizontal rotating drums that tumble the green coffee beans in a heated environment. The heat source can be supplied by natural gas, liquefied petroleum gas (LPG), electricity, or even wood. The most common employ indirectly heated drums where the heat source is under the drum. Direct-fired roasters are roasters in which a flame contacts the beans inside the drum; very few of these machines are still in operation.
  Fluid bed or hot-air roasters force heated air through a screen or perforated plate under the coffee beans with sufficient force to lift the beans. Heat is transferred to the beans as they tumble and circulate within this fluidized bed.
caption: Diedrich infrared drum machine: One of the most common roasters used to roast coffee beans.[citation needed]
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