Visual and Genetic Distinctions
While the difference in kernel arrangement is the most obvious visual trait, the true importance lies deeper, in the grain's chemical makeup. Two-row barley has a larger, more symmetrical kernel, with only two rows of grains on the stalk. This larger kernel size generally translates to a higher starch-to-protein ratio. In contrast, six-row barley kernels are arranged in six rows and are typically smaller, thinner, and less uniform in size. This denser arrangement is often linked to its higher protein and enzyme content, which dictates its use in various applications.
The Impact on Brewing and Distilling
For brewers and distillers, the divergent properties of two-row and six-row barley are critical decision points. The choice of base malt heavily influences the final product's flavor, body, and clarity.
Two-Row Barley in Brewing:
- Flavor Profile: Prized for its clean, smooth, and full-bodied malt flavor, two-row is the preferred base malt for many craft breweries, particularly in Europe. Its lower protein content helps avoid haze and promotes a crisp finish.
- Higher Yield: The higher starch content of two-row barley results in a greater yield of fermentable sugars per pound, offering higher extract efficiency.
- Usage: It is commonly used in all-malt recipes where a clean, malty character is desired.
Six-Row Barley in Brewing:
- Diastatic Power: The higher enzyme content, or diastatic power, of six-row barley makes it exceptionally efficient at converting starches into fermentable sugars. This is particularly useful when using adjuncts like corn or rice, which lack their own enzymes.
- Protein and Flavor: The higher protein level can lead to a more complex, sometimes described as 'grainier', flavor and can increase head retention. However, it can also lead to issues with haze if not managed correctly.
- Adjunct Use: Major American breweries have historically favored six-row for its ability to ferment starches from less expensive adjuncts, making production more economical.
Comparison of 2-Row vs. 6-Row Barley
| Characteristic | Two-Row Barley | Six-Row Barley |
|---|---|---|
| Diastatic Power | Lower | Higher |
| Protein Content | Lower (11-13%) | Higher (12-13.5%) |
| Starch Content | Higher | Lower |
| Kernel Uniformity | More Uniform (plumper) | Less Uniform (thinner) |
| Flavor Profile | Fuller, cleaner, and maltier | Often grainier or sharper, sometimes with an astringent finish |
| Husk Content | Thinner | Thicker |
| Brewing Use Case | All-malt recipes, classic ales and lagers | Adjunct brewing, American lagers, and historical styles |
| Typical Origin | European | North American |
Agricultural and Economic Factors
The differences between these barley types extend beyond the brewhouse and into agricultural cultivation. Two-row varieties are often preferred in regions with milder climates, like Europe, where they can be grown with lower protein content. Six-row barley, on the other hand, is better adapted to the more variable growing conditions found in parts of North America, offering higher yields per acre. This hardiness has historically made it a more readily available and less expensive base grain, a key factor for larger commercial breweries. However, modern breeding has worked to improve the characteristics of both varieties, blurring some of the historical distinctions.
The Final Product: Flavor and Fermentability
Ultimately, the choice between two-row and six-row barley boils down to the brewer's desired outcome. The lower protein and higher starch content of two-row yield a smoother, richer mouthfeel and more pronounced malt flavors, ideal for many traditional craft beers. Six-row's robust enzymatic activity, while sometimes leading to a grainier flavor or haze issues, provides the necessary horsepower for recipes with significant amounts of unmalted grains. This allows for greater cost control and the creation of specific American-style lagers. The trade-offs in flavor complexity, fermentability, and cost are the most critical considerations for any brewer deciding between these two foundational grains.
Conclusion
While visually distinct, the most important difference between 2 and 6 row barley lies in their fundamental biochemistry: protein, starch, and enzyme content. This single factor creates a cascade of effects that influences everything from malting efficiency to the final beer's flavor profile, body, and clarity. Two-row offers a cleaner, malt-forward character ideal for classic ales, while six-row provides the high enzymatic power needed for fermenting adjuncts in traditional American lagers. The choice reflects a brewer's recipe, desired beer style, and economic considerations, making neither inherently superior but rather uniquely suited for different brewing applications.
The Role of Adjuncts
Adjuncts are unmalted grains or fermentable sugars, like corn or rice, that are used in brewing to supplement the grist. They typically do not contain the enzymes needed to convert their own starches. This is where the high diastatic power of six-row barley is invaluable. A brewer can use a cheaper, less flavorful adjunct to lower costs while relying on the six-row malt's potent enzymes to complete the necessary conversion. Two-row barley, with its lower enzyme levels, is better suited for all-malt brews where high diastatic power isn't a necessity. This strategic use of six-row with adjuncts is a cornerstone of large-scale commercial brewing.
