The mash, as described so far, contains only the malt and brewing water. The malt, as stated above, supplies the enzymes and the enzyme substrates. Many of the European beers, as well as the micro-brewed beers produced in the United States, are made using 100% malt mashes. However, the most widely-consumed beers in the United States, those made by the large breweries, contain an additional source of starch-containing material in the form of corn, rice flakes, or grits. These materials are called adjuncts, and can account for as much as 60% of the total mash solids.Adjunct syrups, which contain sucrose, glucose, or hydrolyzed starch, are also commonly used. Adjuncts are allowed in most of the world, but their use is actually forbidden in some countries, including Germany, where centuries-old beer purity laws are still enforced (Box 9-3).
Adjuncts have several functions. First, they dilute the strongly flavored, dark-colored, "heavy" characteristics of the malt. Although these properties are preferred by some beer drinkers, most U.S. consumers favor the paler color and milder flavor associated with adjunct-containing beers. Second, adjuncts increase the carbohydrate content and provides the amylase enzymes with an additional source of substrate, and, ultimately, more fermentable sugar for the yeast. Third, they reduce the carbohydrate-to-protein ratio, such that less haze-forming proteins are present in the finished beer. Finally, adjuncts are less expensive than malt as a source of carbohydrate and, therefore, reduce the ingredient costs. In the United States, 70% of the adjuncts are corn or rice grits. The two brands that dominate the U.S. market, Bud-weiser and Miller, both incorporate adjuncts in their formulations.
It is important to recognize that adjuncts are not essential, since malt contains as much as 70% soluble carbohydrate, which is more than enough to satisfy the energy and carbon requirement of the yeast. As noted above, adjuncts lower the protein:carbohydrate ratio, so if too much adjunct is added, relative to malt (e.g., >1:1 ratio), there may not be enough protein for the yeast.When adjuncts are used, they are usually added to brewing water in a separate tank (cereal cooker). The mixture is brought to a boil to pre-gelatinize the starch and is then added to the mash tun.
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