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. The husk of the malt is high in polyphenols (tannins) that contribute not only to haze, but also imparts an astringent taste.
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.
In comparison to six-row barley, two-row has a higher starch content-the principal contributor to extract. Extract is a major economic concern for many large-scale brewers because the amount of brewhouse extract obtained determines the amount of beer that can be produced from a given amount of malt. Small-scale brewers, however, are generally less concerned about extract yield and may not consider this as important a criterion in their malt choice.
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. Since they must overlap, they twist as they grow. In two-row barley there are no lateral kernels-all kernels being straight and symmetrical. The kernels of two-row barley are broader than the central kernels of six-row barley and do not taper as sharply.
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