Barley

Barley, Hordeum vulgare, is a grass that originated in the Fertile Crescent, where wild barley still grows. Brewers distinguish two-row barley, in which only the central flower of each group of three sets grain, from six-row barley, in which a single gene mutation makes the side flowers fertile too. Six-row grains are smaller, with less starch and more protein. Europe grows mainly two-row barley; six-row is widely grown and used in the United States.

Malting barley is grown to a protein specification, typically 10 to 12 % in two-row varieties, lower than feed barley. Its starchy core becomes the sugar that yeast ferments once malting has produced the enzymes to break it down. The husk protects the grain while it germinates and later acts as the filter bed in the brewhouse, which helps give clear wort. Other cereals can be malted, but barley is the pre-eminent malting grain.