Which cereal grain is the most commonly used in beer?

Barley is the cereal grain most commonly used in beer. Brewers usually malt barley by allowing it to germinate briefly and then drying it, creating enzymes that convert the grain’s starch into fermentable sugars during mashing.

Barley is especially valuable because its fibrous husk helps form a natural filter bed when the sweet liquid, or wort, is separated from the mash. It also provides the malt flavor, color, body, and much of the food yeast needs for fermentation. Nearly all traditional beer styles use barley malt as their main starch source.

Other grains can play important roles. Wheat gives wheat beers a soft body and persistent foam, while rice and maize are common adjuncts in some pale lagers. Oats can add silkiness, and rye contributes a distinctive spicy character. These alternatives do not make barley incorrect: they are usually additions or specialized substitutes rather than the dominant brewing grain.