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. In the malting process protein is broken down in varying extent to its individual building blocks, amino acids. Amino acids such as these form into the enzymes necessary for grain modification during malting and starch conversion later in brewing. Therefore six-row’s higher protein favors higher potential for enzymatic activity. The higher level of diastatic enzymes makes six-row barley desirable for conversion of adjunct starches (those that lack enzymes) during mashing.
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 (Figure 2.1). 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. Two-row barley is usually preferred for craft and all-malt brewing.
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.
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