Base Malt Basics

Some brewers tend to think of base malt as a key source of fermentable sugar, protein, yeast nutrition and minerals — but not as a major contributor to beer flavor. These brewers are missing the point. In fact, the choice of a particular pale-colored malt — or “base” malt, as we sometimes call it — is a crucial decision when designing a beer in which the “malt” flavor is important.

Base malts account for most of the grain bill in many styles of beer. Different base malts produce different flavors, so it’s critical to choose the right base malt when brewing a particular style. The base malt becomes even more important when brewing styles with lighter colors and delicate flavors. With a beer that highlights the flavors of darker and more flavorful specialty malts, like stouts, the base malt flavor is less important.

Flavors developed in malting

There aren’t many things that taste or smell like malted barley. In fact, the word that’s used to describe some of the compounds produced during kilning is “malty.”

Barley must be converted into malt  to produce the flavors we associate with beer. The maltster is responsible for producing malt that’s acceptable to brewers in terms of two central criteria:   brewery performance and extract efficiency. I recently attended a talk at which a representative from a leading malt company suggested adding “flavor” to that list of criteria.

“Modification” is the part of the malting process in which enzymes chemically re-arrange the structure of the barley kernel. Proteins are degraded, beta glucans are solubilized and starches are broken down. An extended modification period leads to increased levels of “cold water extract,” which really means more soluble sugars and amino acids.

When these compounds are exposed to heat in low-moisture conditions, they combine in numerous ways to produce many flavor and color compounds. The simpler compounds give rise to flavors and the more complex give rise to colors. These reactions are known as “Maillard reactions” and occur in many food products that are exposed to similar low-moisture heat, such as baked breads or cured meats (browned toast is an example of the Maillard reaction). Also produced are compounds known as reductones that consume oxygen and may help stabilize finished beer.

Prolonged kilning also drives off unwanted flavors and aromas. One such aroma is dimethyl sulfide (DMS). This compound may smell of cooked corn when present in low levels and at high levels may resemble stewed cabbage, onion or garlic. It is formed from a pre-cursor called s-methyl methionine (SMM). SMM is converted to DMS by heat, so prolonged kilning first converts and then removes the potential to produce this flavor. Many drinkers who smell corn in their beer make the false assumption that corn was used in the recipe, due to this compound.

Base malts: a quick history

It is interesting to note that the beer styles made famous by each of the world’s brewing regions are the products of prevailing brewing conditions and available ingredients. Just as a particular water type leads to a particular beer style, so too could a barley breed or a hop variety give rise to a region’s signature beer. It is more likely that the brewing method employed in the Czech Republic (decoction mashing) or England (infusion mashing), for example, originally had more to do with barley and malting methods than a preference from the brewer.

In modern breweries, however, the brewers have an important role in determining the qualities of the malt they brew with. While allowances are still made for local weather conditions and the barley varieties that grow there, maltsters now produce malt to suit the brewer’s needs.

Below is a guide to the five main kinds of base malt. Before I forge ahead, a caveat: This list is not comprehensive. Unique grains like peat malt and acid malt are considered base malts; specialty malts like Munich and Vienna can comprise 100 percent of the grain bill in some styles; and malts made with North American barley in the British tradition, such as Briess or Great Western pale ale malt, are becoming popular. But the five malts I discuss in this article are the building blocks for an enormous collection of common beer styles.

Traditional Bohemian pilsner

Bohemian pilsner is slightly darker than domestic malt (about 3 to 4 degrees Lovibond). It’s low in protein (10 to 11 percent) and fairly undermodified. This base malt is famous for its golden color, viscous mouthfeel, sweet middle palate and bready but dry finish. These characteristics  define the finished beer because of the undermodified malt and the decoction mash system that’s still employed in the Czech Republic.

It’s possible to recreate all of these characteristics by using some of the specialty malts made available to us over the years, so I would not advocate a commercial brewery taking the time or expense to recreate the European decoction process. But homebrewers should be encouraged to experiment. In fact, homebrewers can buy malts that are made and intended specifically for a decoction mash.

Moravian barley is renowned for its brewing qualities and was once considered the finest in the world. The modification process is arrested long before it is complete, and the kilning process is deliberately carried out at lower temperatures. This results in less breakdown of the carbohydrates, protein and beta glucan in the grain and the survival of a higher proportion of the malt’s enzymes, especially those that break down protein and beta glucan. Historically, all malt in this part of the world was made this way.

I once met a German brewer who complained that the “damned maltsters were doing all his work for him.” He meant that a large portion of the protein, the beta glucan and the small starch granules had already been broken down and largely solubilized. So he didn’t have to employ an interesting range of temperature rests and perhaps decoctions to deal with them in the brewhouse!

British pale ale malt

British pale ale malt is produced in the United Kingdom. The color is a bit darker (4 degrees Lovibond) and the barley is low in protein (9 to 11 percent). The malt is well-modified, dried to a low moisture specification and has more “malt” flavor. The grain bed will be bouyant in the mash tun and will yield good extract efficiency with a single temperature rest in the mash. In short, it’s intended for brewers who make the traditional low-carbonation, cask-conditioned ales we think about when we think about British beers.

Brewers of these cask-conditioned beers have specific requirements of their malt. In an infusion mash it is vital that the malt be fully and evenly modified — not just from kernel to kernel, but also within each kernel. This is necessary for efficient wort separation.

To achieve this even modification, malting is carried slowly and at a cooler temperature. Cask beers are unfiltered, so the malt can’t contain too much protein or the beer will be difficult to clarify. Historically, British brewers used fairly rudimentary mills, so they needed malt with a low moisture content (dry malt literally bursts apart in a simple mill). They also favored a single-temperature infusion mash — and had no method of temperature adjustment in the mash vessel  — so low-moisture malt made hitting the correct mash temperature easier. These beers are fairly low in alcohol content, so malt with a lot of flavor contribution was preferred. To achieve this low moisture, and yield stronger flavors in the finished beer, the malt is kilned longer and at higher temperatures than its European counterparts. This means it has fewer enzymes, since more of them are destroyed by the heat of the kiln. Any hope that there would be any enzymes present capable of breaking down complex proteins is a vain one, so brewers skip all the rests and use a compromise temperature at which the key enzymes that break down starch are active.

Barley variety is more important to British brewers, since many insist on using a single variety of barley malt for their recipes. The most famous variety may be Maris Otter, which has a long-established reputation for producing full-bodied, clean-tasting, clear beer. In Scotland I used a variety called Golden Promise; it provides the unique flavor profile that I associate with Scottish beers.

European pilsner malt

This malt is low in color (2 degrees Lovibond) and low to medium in protein (10 to 11 percent). It’s high in enzymes, extract and potential DMS. It’s used for European lager, which happens to be the leading kind of beer produced these days in Britain.

As the popularity of European lager rose in the United Kingdom, British brewers found it difficult to brew these light-colored beers using traditional British pale ale malt. So maltsters began producing an even paler malt, which brings with it other issues. The lager malt is less extensively kilned, which results in higher moisture and more DMS potential. The result is that the DMS flavor is an integral part of beers brewed in this region of the world, and should be present in beers that represent the style well.

A friend of mine who trained in Germany and now works at a major brewery was concerned about the DMS in his German pilsner. We both agreed it was a little high but needed to be noticeable. The need to use a higher level of brewing adjuncts results in a parallel need for higher levels of enzyme in the base malt. Adjuncts are used to dilute color, dilute troublesome nitrogen (protein) and dilute flavor. They also improve flavor stability. As a friend once said when asked why he used 25 percent sugar in his kettle, “that’s 25 percent of the ingredients I don’t have to worry about.”

North American six-row

North American six-row malt is pale in color (less than 2 degrees Lovibond) and high in protein (12 to 13 percent). It’s extremely high in enzyme potential to take advantage of the fact that a lot of adjunct starch will be used in the brew. It’s ideal for low-color, low-flavor, high-adjunct beers such as Budweiser, Miller and Coors.

There are essentially two types of barley grown in America. With six-row barley, the kernels are arranged around the stalk in threes (the triads are offset and look like six when viewed down the axis of the head). With two-row barley, the kernels are in pairs. Six-row barley varieties are only grown in North America and malt from Europe is always two-row.
Six-row kernels tend to be long, thin and narrow, while the two-row tend to be plumper. The six-row have less endosperm and more husk. Six-row barley is malted with the production of pale-colored, light-bodied, mild-tasting lager beers in mind. Six-row has a high enzyme potential, as indicated by its higher nitrogen level, and it is kilned for a low color. It will provide a slightly lower extract potential.

The brewer will use up to 50 percent non-malt adjunct, which will dilute the nitrogen considerably, along with the reserve of enzymes. This means that brewers usually will perform a low temperature rest in the mash to increase the amino acid level of the wort. This helps ensure that there is plenty of nutrition for the yeast. They will also allow the temperature of the mash to rise slowly through the different active ranges of the two starch degrading enzymes to ensure a controlled degree of fermentability in the final beer.

North American two-row

Domestic two-row malt is pale in color (less than 2 degrees Lovibond) and high in protein (12 to 13 percent). It has slightly less enzyme potential than six-row and slightly more extract potential.  It is used as the main base malt in a wide range of beer styles. Produced by maltsters to big brewery specifications, this malt will support high levels of adjunct.

A lot of homebrewers — and small commercial brewers, for that matter  — are guilty of thinking of two-row as the ideal malt for brewing British ales. It actually should be used to make fine American ales. But bear in mind that this malt, like six-row, is made predominantly for the large producers of pale lagers. Again, maltsters maximize the enzyme potential, care a little less about nitrogen, kiln lightly for a paler color, and leave the moisture content a little high. This malt can be used in infusion mashes. One advantage of having such an enormous surplus of conversion enzymes is the fact that the conversion of starch to fermentable and unfermentable extract in the mash tun is very rapid. The light kilning can lead to the inappropriate appearance of DMS in ales, so great care must be taken in the boil to guard against this. Brewers commonly use only a few varieties — such as Harrington, which is higher in protein and DMS potential. Maltsters also sell a blend of two or three barley varieties as their “two-row malt blend.”

Issue: October 2001