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Beer Adjuncts
Cereal Adjuncts
Most of the brewers’ adjuncts are based on a limited range of cereal grains. The nonmalt brewing materials used in greatest quantity today are those derived from corn and rice, although barley, wheat, and sorghum grain are sometimes used.
Grits
Grits consist of uncooked fragments of starchy endosperm derived from cereal grains. The starch of these adjunct products is in its native form, and is not readily attacked by the malt diastase enzymes during mashing. Consequently, these adjuncts must be processed by boiling in a cereal cooker to bring about solubilization and gelatinization of the starch granules and render them susceptible to diastatic enzyme attack. Unlike in America and Australia, grits are rarely used in British brewing, as cereal cookers are not found in most traditional British breweries.
Flakes
There are two different manufacturing processes used to produce brewing flakes. In the traditional process, corn and rice grits or whole barley are steam-cooked to soften the endosperm, which is then rolled flat and dried. Gelatinization occurs during the steaming process. More recently, these materials are "micronized" prior to flaking by subjecting the grain to internal heating by infrared heat. Flakes can be added directly to the mash tun since the starch granules have been gelatinized. They are usually added during or at the end of the protein rest (8). Flaked cereals have been used for many years in the United Kingdom and Belgium, being valued for the soft and subtle grain-like sweetness they impart.
Torrified Cereals
Torrified cereals are produced by heating the grain, which makes the endosperm expand and pop, thus rendering the starch pregelatinized and easily milled. Torrified cereals can be added directly to the mash tun since the starch granules have been gelatinized. Most of the nitrogen is denatured in the kernel and is not solubilized, thus contributing little or no nitrogen to the mash. They can be ground simultaneously and mashed-in together. However, higher yields are found by cooking the torrified product separately between 71 and 77ºC prior to adding it to the malt mash (30). Fat content is slightly higher than for other adjuncts, but this is usually not an issue when using a higher adjunct level (5).
Micronized Cereals
Micronized cereals are produced by heating the grain with infrared energy, causing the molecules in the grain to vibrate and heat up, which results in a rapid rise in water vapor. The grain becomes soft and turgid, thus gelatinizing the starch. Most of the nitrogen is denatured in the kernel and is not solubilized, thus contributing little or no nitrogen to the mash. The grains are either used as micronized material or flaked in a roller mill.
Refined Starches
Refined starches can be prepared from many cereal grains. In commercial practice, refined wheat starch, potato starch, and cornstarch have been used in breweries; corn starches, in particular, are used in the preparation of glucose syrups. Wheat starch has been employed in breweries in Australia and Canada, where local conditions make it economical to use. However, the most important source of refined starch is corn.
Barley Cereals
Unmalted barley gives a rich, smooth, "grainy" flavor to beer. Unlike the other adjuncts, unmalted barley will contribute foam (head) retention to the finished beer because of lower levels of proteolysis (30). However, the nitrogenous and complex proteins that contribute to head retention also contribute to chill haze problems. Clarity problems make unmalted barley inappropriate for light beers, which is one reason why corn and rice are preferred. It is essential in dry stout, e.g., Guinness Stout.
Corn Cereals
Corn products have traditionally been the adjunct of choice among brewers. They are extremely consistent in terms of quality, composition, and availability and produce a spectrum of fermentable sugars and dextrins similar to that produced by malt upon enzymatic conversion.
Oat Cereals
The high protein, fat, and oil content of oats is theoretically a deterrent to their use in brewing. However, oats have been used in the brewing process, particularly in brewing oatmeal stout.
Rice Cereals
Rice is currently the second most widely used adjunct material in the U.S. in the production of light-colored lager beers (30). Rice has almost no taste of its own, which is regarded as a positive characteristic since the rice will not interfere with the basic malt character of the beer. It promotes dry, crisp, and snappy flavors and is employed in several premium brands, including Budweiser. Some brewers prefer rice because it has a lower oil content than corn grits (5). One disadvantage in using rice is the need to use an additional cooking vessel because its gelatinization temperature is too high for adequate starch breakdown during normal mashing.
Wheat Cereals
Unmalted wheat often is used as an adjunct by brewers who wish to enhance head retention and foam stability. It also contributes to the body or "palate fullness" of the beer. Its high content of proteins greatly enhances foam stability. Beers made from significant amounts of wheat adjuncts are likely to be light in flavor and smooth in taste qualities. Wheat adjuncts are used in the same manner as barley adjuncts; but unlike with barley, there is almost no husk in wheat. Thus, tannins are not much of a problem. The gelatinization temperature range for wheat is between 52 and 64ºC.
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