wheat

cultivation for both bread and beer making is as old as civilization itself. Human nutrition—in fact all creature nutrition on earth—is based essentially on only three major groups of compounds: carbohydrates in the form of starches and sugars, nitrogen-based proteins, and water. Less bulky, but also critical for human health, are a large number of trace elements such as minerals and vitamins. The seeds of grasses, which we call cereals, especially wheat, happen to contain an almost perfect natural combination of all these essential ingredients of human sustenance. They are rich in starches and proteins and they contain small amounts of lipids (fats) in the form of germ oils (concentrated carbohydrates) as well as a varied assortment of trace elements. They even have some fiber in the form of cellulose to make the entire package excellently suited for the human system. Our predilection for grass seeds is fortunate, because grasses are both ubiquitous and infinitely versatile; and humans have learned to turn them into many basic food preparations, including breads, porridges, and beers.

Of all the grass seeds, wheat is probably the best suited for bread making, because four-fifths of its proteins are made up of gummy glutens. These are the characteristic wheat proteins that make dough sticky, cohesive, and elastic. For brewing, however, these proteins must be degraded, because a viscous, gummy drink is a rather poor thirst quencher and a difficult dinner companion. Wheat, unlike other cereals, also lacks enzymes that can convert unfermentable starches into fermentable sugars. See amylases, enzymes. Finally, wheat lacks husks. If a mash were made up entirely of wheat, it could combine into a pasty mass, which would prevent proper wort extraction during the lautering process. See husk, lautering, mash, and wort. Barley, by contrast, is virtually perfect for beer making. It is relatively low in gluten and it has great diastatic power for starch conversion. See barley, diastatic power. It also has plenty of husk material, which gives it double the cellulose content of wheat—0.5% of dry weight versus 0.25% of dry weight. This is why barley, unlike wheat, makes for a natural filter bed for great extraction values during wort run-off. When using wheat in beer making, it is essential that it is paired with a good portion of barley malt or other husk- and enzyme-rich malt. Only a mixed mash ensures that there are enough enzymes to effect conversion of all starches, including those contained in the wheat. In practice, wheat beer brewers tend to use at least 30% non-wheat grist in the mash. The table contains a comparison of barley, wheat, corn, rye, and oats in terms of compounds relevant to beer making.

Given the composition of wheat, it is somewhat surprising that even mankind’s earliest brewers, who obviously had no understanding of enzymatic mash activities, used not only barley but also several varieties of wheat—usually in combination—in their mashes. According to the best archaeological evidence, the first brewing of both barley- and wheat-based beers was concurrent with mankind’s first settlements and earliest agriculture—both considered breakthroughs in human social evolution. This was about 8,000 to 10,000 years ago in what is now Iraq, in the fertile plains between the rivers Tigris and Euphrates, where a people called the Sumerians abandoned their hunter-and-gatherer ways and became farmers, bakers, and brewers. See sumer. We consider that change in lifestyle the beginning of history and civilization as we know it, and beer making was part of that transformation. The grains available to these Neolithic brewers were the heirloom ancestors of today’s barley and wheat varieties.

When brewing started, the Sumerians probably used a wheat variety called Triticum monococcum. It has very hard kernels as well as firm husks and is still occasionally grown today, mostly as an heirloom cereal for specialty foods. It is now commonly referred to by its German name of Einkorn, and we consider it the primordial progenitor of all modern wheat (Triticum aestivum). See einkorn wheat. In Sumerian times, Einkorn got crossed somehow, probably by open pollination, with wild grasses, which resulted in an advanced, relatively softer, husked wheat, Triticum dicoccum, which is now known also by a common German name, emmer. This wheat, in turn, spawned another cross, again with wild grasses, called spelt (Triticum spelta), which represented the next advancement in wheat cultivars. Spelt, also known by its German name of dinkel, is still planted today, and it is used for both specialty bread and beer, often organic. See emmer, spelt. Spelt cultivation moved from the fertile crescent of the Middle East to other parts of the ancient world, perhaps in part because it places few demands on soil quality and climate. It can grow where modern wheat cannot. In central Europe, for instance, spelt is known to have been cultivated at least since the late Bronze Age, some 3,000 years ago, mostly in the regions inhabited by the Alemans, a Germanic tribe that roamed what is now the German State of Baden-Wurttemberg and the German-speaking part of Switzerland. Spelt is fairly high in protein content, up to about 17% compared with modern wheat, which has about 12% to 14.5%. This is why spelt-beer mashes rarely contain more than 50% spelt. Although spelt husks would be useful as a filtration substrate in the mash, they are usually removed in the malt house nowadays because of their high astringency, which would make the beer taste too rough for a modern palate. Centuries of breeding improvements eventually turned the ancient spelt into our modern, now huskless, wheat.

The world grows about 650 to 700 million metric tons (MT) of wheat per year. The exact quantity varies from year to year, with the variation mostly dependent on weather conditions. Given an overall world cereal production of roughly 2.25 billion MT—which includes corn, barley, sorghum, and millet—almost one-third of all cereal cultivation is wheat. Roughly 20% of that wheat is grown in the European Union and slightly less than that in China. India accounts for slightly more than 10% of world wheat production, whereas Russia and the United States each account for slightly less than 10%. Other significant producers of wheat are Australia, Kazakhstan, Pakistan, and Ukraine, each with roughly 3% to 4% of world production.

Only a tiny fraction of the world’s wheat goes into brewing. In fact, given the small worldwide demand for wheat by the brewing industry compared with the food-processing and feed-lot industries, virtually all wheat is bred and cultivated exclusively for non-beer purposes. Even in Germany, with its strong weissbier market, where almost 1 of every 10 beers consumed is a wheat beer, only 0.5% of the roughly 25 million metric tons of wheat produced there make it to a malt house and from there to a brewhouse. See weissbier. Unlike barley, of which many strains are bred in many countries by public institutions and commercial crop breeders specifically for brewing, no similar breeding programs exist for brewing wheat strains, which means that maltsters often cannot get the wheat selection they like at harvest time. Brewers, unless they have made their own arrangements with farmers, are invariably stuck with whatever the maltster can procure in markets that are not geared toward brewing.

To be sure, there are some wheat varieties with characteristics that make them much better suited for malting and brewing than others. However, these are often only marginal varieties as far as breeders and farmers are concerned. Although maltsters and brewers prefer grains with a protein content below 12%, the core of wheat-strain breeding focuses on varieties with the highest amount of protein, called E-wheat in Europe, which stands for “elite wheat.” E-wheat has at least 13.3% protein and generates the best economic return for farmers and breeders. In terms of quality rankings, E-wheat is followed by A-wheat (“quality wheat” with at least 12.5% protein), B-wheat (“bread wheat” with at least 12.2% protein), K-wheat (“cookie wheat” with at least 12.5% protein), and C-wheat (all others). In either of these categories, the wheat may be planted as winter or spring wheat, although the majority of the world’s wheat is winter wheat. Breeders have very little incentive to focus on varieties other than E because the return on investment from licenses and the sale of seeds for cultivation is insufficient to amortize the high cost of research and development, which some breeders in Europe report as being in the neighborhood of 17% of sales revenues, not counting the cost of regulatory compliance and marketing. This up-front investment is fairly high by overall industrial standards. Even the American pharmaceutical industry, which has unusually high research and development costs, tends to invest only about 18% of its annual domestic sales in research and development activities.

The challenge for maltsters is to select brewing wheat from what is essentially a stream of baking wheat while using trade-atypical criteria. The only alternative for maltsters is to enter into special forward contracts with farmers, who will then grow malting- and brewing-friendly wheat varieties because they have a guaranteed market and a guaranteed price. Only contracts can also guarantee that a batch of raw wheat is of only a single variety instead of a mix of several varieties, which would not have uniform malting characteristics. Current wheat varieties that are considered of high malting and brewing quality include Anthus, Tabasco, Skalmeje, Hermann, and Mythos. In recent years, when wheat supplies have been low and prices high, some wheat beer brewers have found that even their signed contracts did not always protect them, with the farmer having found a suitcase full of cash a more compelling offer.

Interestingly, although the introduction of brewing barley varieties into commercial cultivation is strictly regulated by certification processes in most countries, there are no equivalent certification standards for brewing wheat, which means there are no variety registries for the maltster and brewer to consult when choosing wheat for brewing. The selection criteria for good brewing wheat, therefore, are more a matter of practical experience. In this process, it helps if the maltster knows for which type of beer the wheat is intended. The key difference is whether the beer will be yeast-turbid like a German weissbier or filtered like a German kristallweizen. See kristallweizen. Whereas the protein- and gluten-related viscosity of the wort and beer is less important for unfiltered beers, it is crucially important for filtered beers. See filtration. Quality barley base malts, for instance, tend to have a viscosity rating of 1.4 to 1.58 mPa second, whereas wheat malts are more likely to have a rating of 1.60 to 2.10 mPa second. A value greater than 1.75 mPa second is considered high, regardless of mash composition, and is likely to cause lautering and sometimes even filtration problems. The higher the viscosity value of the wheat malt, therefore, the less of it can be used in the mash. This makes the mash composition a delicate balancing act for the brewer trying to make a yeast-turbid beer, because too much viscosity causes process problems, whereas too little viscosity may allow the yeast to settle out quickly, giving the beer an unwanted clarified appearance. In yeast-turbid wheat beers, a good amount of suspended proteins is a plus, helping to stabilize the beer’s turbid appearance, because, perhaps unknown to the consumer, much of the opacity of many wheat beers is derived not only from yeast in suspension but also indirectly from hazes. Haze-forming complexes can envelop yeast cells and thus prevent them from becoming part of the sediment. See chill haze, colloidal haze, and haze.

In general, large proportions of wheat also tend to give beer a certain lightness of mouthfeel along with a dash of refreshingly crisp acidity. Wheat varietal differences can have significant implications for the flavors and aromas of the finished beer. For instance, differences in the composition of a wheat variety’s amino acids influence the ester content of the beer after fermentation. See esters. This, in turn, influences the beer’s flavor and aroma. Many wheat beer styles have estery notes as part of their normal style profile. The amount of variety-specific ferulic acid is crucial too, because this acid is largely responsible for the synthesis of 4-vinyl guaiacol, which is the very compound that generates the signature fruity–clovey flavors generally associated with German wheat beers. See 4-vinyl guaiacol, ferulic acid. For weissbier wheat malts, therefore, the ferulic acid character is even more important than the malt’s modification, whereas for quality barley malt, by contrast, modification is one of the key selection criteria. See modification. For these reasons, brewers look for wheat malt specifications and descriptions that include such phrases as a “phenolic aromas,” “ester aromas,” “yeasty aromas,” and “malty aromas,” depending on the type of wheat beer they wish to produce. Also crucial in the selection of wheat for malting and brewing is the variety’s known resistance to fusarium, a common mold whose toxins can leach into the beer. There the toxins can serve as nuclei for the aggregation of large carbon dioxide bubbles, which, when the bottle is opened, can cause the sudden and vigorous eruption of the beer—a defect known as gushing. See fusarium, gushing.

The production of malt from wheat is not different in principle from the production of barley malt. See malt, malting. However, because wheat has no husks, “naked” wheat kernels absorb water much faster during the steeping phase than do husk-wrapped barley kernels, which is why steeping times for wheat tend to be much shorter than for barley. Once transferred to the germination chamber, the lack of husks also causes wheat kernels to be much more closely packed than barley kernels. This, in turn, results in more germination heat to be generated and retained, thus potentially accelerating germination out of control. To slow the process down and to ensure germination homogeneity, the maltster must reduce the temperature in the germination chamber and keep the wheat layer at a lower depth than a comparable barley layer. However, because the lower temperature slows down germination, it also favors higher protein modification, even to a point of causing portions of the degraded proteins to ooze out of the aleurone layer and to glue the wheat kernels together. See aleurone layer. Reducing the water content during germination is one way to keep excessive modification in check. Increased turning of the germinating wheat malt, on the other hand, which could alleviate clumping, would run the risk of damaging the delicate kernels, especially the acrospires. This would cause a slowdown of the kernel’s internal chemical changes and reduce the malt’s quality for brewing. See acrospire.

Clumping can also pose problems in the kiln, because aeration of the malt would not be even, and the sticky kernels would not dry homogeneously. Because of the lack of husks, the initial kilning temperature of green wheat malt is generally kept lower than for green barley malt—by roughly 5°C (10°F). This prevents an excessive coloring of the malt from the relatively large amount of amino acids (a degradation product of proteins) in wheat malt. See amino acids. After kilning, wheat malt, just like barley malt, is polished to remove the rootlets and the now dead, protein-rich acrospires. In barley, the acrospire grows inside the husk and only the protruding portion is removed in the polishing process, whereas in wheat, without the husk, the entire acrospire is removed. As a result, wheat malt loses about 0.5% to 0.7% of its protein content during the polishing process. Analytically, the finished wheat malt differs from barley malt mostly in terms of the chemical structure of the proteins. In wheat malt, the proteins are mostly large-molecular compounds, whereas in barley malt they are largely modified into small-molecular structures. This leaves plenty of wheat proteins for the brewer to degrade in the mash tun, which means a multistep mashing process is definitely advisable in wheat beer making. Once properly degraded in the brewhouse, these proteins are then responsible for the firm and long-lasting creamy head, which is one of the characteristics of a well-brewed wheat beer.

A brewer can add any proportion of wheat to the grist, except in Germany, where a brew may be called a weissbier only if the mash contains at least 50% wheat malt and if the brew is fermented with top-fermenting yeast only; that is, in Germany, all wheat beers are warm-fermented ales. Highly malt-accented wheat beers usually have a good portion of caramel malts in the grain bill as well. See caramel malts. Pale, spritzy weissbiers, on the other hand, are generally less malty, whereas their fruity, banana, bubblegum, clove-type notes—produced by specialty weissbier yeast strains—dominate the taste and aroma. Next to the German weissbier, perhaps the most common wheat beer style is the Belgian wit beer or bière blanche, which is usually made with about 20% unmalted wheat. Then there is the sour Berliner weisse, a sparkling ale made from a mash with a wheat malt portion rarely exceeding 30%. Belgian lambics, too, contain unmalted wheat, sometimes up to 40%. Finally, American craft brewers now make a large variety of wheat ales, which usually contain anywhere from 10% to 35% malted wheat and are often fermented with regular ale or lager yeasts as opposed to weissbier strains. See american wheat beer. These are sometimes mislabeled as “hefeweizen,” although they have no classic hefeweizen (weissbier) yeast character. There is an increasing interest in wheat varieties among craft brewers worldwide, with many brewers exploring spelt, emmer, and other ancient wheat varieties alongside the modern ones.