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It seems to me that a lot of homebrewers stay away from using 6-row barley as a base-malt, but the question is, do they know why? There seems to be a near ubiquitous lack of knowledge as to the attributes of 6-row. Yes, American 2-row, Maris Otter and Pilsner malts (all of the 2-row spec.) are much more commonly found base malts in the recipes that are available in books and online, but almost all of the American macro breweries are using 6-row. We can therefore assume that 6-row is the most common base malt used in America (based on volume). What do they know that we don’t?
I found an excellent article entitled A Comparison of North American Two-Row and Six-Row Malting Barley by Paul Schwarz and Richard Horsley online. It may not be the be-all and end-all article on the subject but I found it to be highly informative and I have based my findings here on the information presented in said article.
I should preface that history, as is so often the case in brewing, has played a large role in the traditional usage of 6-row vs. 2-row. In the early days of brewing in America, 6-row was likely used more often because it was planted with more regularity than 2-row. This is simply because it was better suited to flourish in the climate of the growing regions there. In these modern times, the evolution of the agricultural industry has changed that situation. In some cases, breweries may still use 6-row out of habit from those early days but it’s important to know that, as far as growing a brewing quality barley goes, of either type, you can now consider them on a level playing field.
As far as the name goes, it’s much simpler than you make think. All barley has what’s called a “spike”, or flower, at the end of the grassy stalk. These spikelets open upon maturity as to spread their seeds to reproduce. 2-row barley literally has 2 rows of seeds or kernels in their spikelets. 6-row has, you guessed it, 6 rows of kernels.
Here is some analytical data from A Comparison of North American Two-Row and Six-Row Malting Barley that will hopefully make more sense after completing this article.
Table II: Comparative Analytical Data* Two-Row Six-Row
Extract (% dry basis) 81.0 79.0
Total protein (% dry basis) 11.5 12.5
Soluble protein (% of the malt, dry basis) 5.0 5.5
Soluble total protein (%) 43.5 44.0
Diastatic power (�Lintner) 120 160
a-amylase (dextrinizing units) 50 45
Wort viscosity (cP) 1.5 1.5
Wort ß-glucan (ppm) 110 140
Wort color (�SRM) 1.5 1.5
*Typical two- and six-row malt quality parameters for barley produced in the United States. Malt quality data represent approximate averages. It must be remembered that considerable variation due to changes in growing conditions, barley quality, or malt processing can occur, even within the same cultivar. Malt quality data are based on the methodology of the American Society of Brewing Chemists.
Some key areas of interest:
Kernel Size and Uniformity – 2-row kernels are highly symmetrical and plumper than those of 6-row. The 2 kernels of 6-row barley that are closest to the stalk are similar to those of 2-row but the outer kernels are smaller and asymmetrical.
Effect on your brew – The plumpness of the kernels can be attributed to the extract yield but modern technology has rendered that factor nearly negligible with 6-row being just 1-2% lower than 2-row. Plumpness (and symmetry), however, play a major role in both the grinding of the grain and the laughter process. 2-row is therefore superior in this area, allowing for a more uniform grind that can have positive effects on brewhouse efficiency and ease of the sparge process.
Husk Content – 6-row, due to its thinner kernels, is thought to have a higher husk content than 2-row.
Effect on your brew – A higher husk content is advantageous in filtering and preventing stuck sparges during the laughtering process but can cause astringency and haze formation in high percentages.
Protein Levels – 6-row barley, generally, has a higher level of wort-soluble protein than 2-row.
Effect on your brew – A higher protein content leads to a lower starch content, which in turn reduces the level of malt extract in the grain. Therefore, 6-row yields slightly less fermentable sugars per pound. Proteins do, however, contribute to mouthfeel, head retention, color, flavor, and yeast metabolism. But, too much soluble protein can lead to too much color development during the boil, problems with filtration, poor clarity, and increased levels of DMS (cooked corn off-flavor). The protein levels in 6-row are in the “too much” category. These super high protein levels can be advantageous in some cases though, which I will get to after I discuss enzymes… because they are linked.
Malt Enzymes – Traditionally, 6-row barley had higher levels of a-amylase enzymes that convert starches to dextrins but modern 2-row has equal or even slightly higher levels of these enzymes. The major difference here is diastatic power (which has to do with ß-amylase enzymes). Diastatic power has to do with enzymes that break down complex carbohydrates in to sugars, or convert starches to fermentable maltose. High levels of protein and diastatic power are positively correlated and therefore 6-row is superior here.
Effect on your brew – A higher diastatic power will lead to faster and more flexible starch conversion during the mash. If you end up mashing at a higher temperature than you had planned, the use of a higher diastatic power grain, 6-row in this case, would allow for a more fermentable wort.
6-row’s superiority in increased soluble protein content and diastatic power is the key reason why it is used so heavily by macro breweries. These breweries, having a core business philosophy of reducing cost, use a lot of unmalted cereal adjuncts such as rice and corn (cheaper than malted barley). The proteins in rice and corn are mostly insoluble and like I said earlier, soluble proteins are important to yeast metabolism and therefore fermentation. So, with the use of 6-row, a brewer can get a good, healthy, fermentable wort from the use of up to 40% cereal adjuncts and save some money in the process.
Though rice and corn are not used often by homebrewers or even craft breweries, the advantages of using 6-row can still be seen with the use of other adjuncts that are used more commonly such as unmalted wheat, unmalted barley and various flaked grains such as oats. One could also supplement their 2-row with a small portion of 6-row to increase extraction, conversion time and fermentability.