Barley, a cereal grain that has been cultivated for millennia grows in two-row, four-row, or six-row form, as distinguished by the number of seeds on the stalk of the plant. Four-row barley is unsuitable for brewing. European brewers traditionally use the two-row type because it has a better starch/husk ratio and because of its malty flavor. Americans often preferred the six-row type because of the higher levels of diastatic enzymes and protein, which makes it better suited for mashing adjuncts, such as corn or rice.
Six-row Barley Malt
Generally, six-row barley has a higher enzyme content for converting starch into fermentable sugars, more protein, less starch, and a thicker husk than two-row barley. The higher level of diastatic enzymes makes six-row barley desirable for conversion of adjunct starches (those that lack enzymes) during mashing. On the down-side, the higher protein content can result in greater amount of break material (protein-polyphenol complexes) during wort boiling and cooling, as well as possibly increased problems with haze in the finished beer.
Two-row Barley Malt
Generally, two-row barley has a lower enzyme content, less protein, more starch, and a thinner husk than six-row barley. American two-row barley has greater enzyme potential than most European two-row barley. The protein content of U.S. two-row barley is comparable to that of continental Europe, while barley grown in the U.K. is generally lower in protein.
Barley Malt Identification
The number of rows of kernels makes for easy identification of two- and six-row varieties. In six-row varieties, two-thirds of the kernels are twisted in appearance because of insufficient space for symmetrical development.
Click on the following topics for more information on barley malts.