Decoction

A decoction is a method of extraction of herbal or plant material, which includes, but is not limited to: Stems, roots, bark, and rhizomes.

Some teas are decoctions. Likewise, the term is used colloquially in South India to refer to black coffee prepared by the traditional method. Decoctions, however, differ from most teas, infusions, or tisanes, in that decoctions are usually boiled.

Decoction mashing is the traditional method used in many German breweries. It was used out of necessity before the invention of thermometers allowed simpler step mashing. But the practice continues for many traditional beers because of the unique malty flavor it lends to the beer. This is the result of Maillard reactions while boiling part of the grain.

Process
Decoction involves first mashing, and then boiled in water to extract oils, volatile organic compounds, and other chemical substances.

In herbalism
In herbalism, decoctions are usually made to extract fluids from hard plant materials such as roots and bark. To achieve this, the plant material is is usually boiled for 8-10 minutes in water. It is then sifted.