Most of the adjuncts used by brewers are derived from a limited range of cereal grains. The most commonly used non-malt brewing materials today are corn and rice, although barley, wheat, and sorghum grains are sometimes used.
Types of Milled Products
Flours are by-products produced during the manufacturing process of corn and rice. These flours need to be cooked before being mixed into the malt mash.
Grits are uncooked fragments of starchy endosperm derived from cereal grains. The starch in these adjunct products is in its natural form and is not easily broken down by malt diastase enzymes during mashing.
There are two different manufacturing processes used to produce brewing flakes. The traditional process involves steam-cooking corn and rice grits or whole barley to soften the endosperm, which is then rolled flat and dried. Gelatinization occurs during the steaming process. Another process involves “micronizing” these materials before flaking by subjecting the grain to internal heating using infrared heat.
Torrified cereals are produced by heating the grain, causing the endosperm to expand and pop. This pre-gelatinizes the starch, making it easily milled. Torrified cereals can be added directly to the mash tun because the starch granules have already been gelatinized. Most of the nitrogen in the kernel is denatured and does not contribute much or any nitrogen to the mash. The fat content is slightly higher compared to other adjuncts, but this is usually not a problem when using a higher level of adjuncts.
Refined starches can be made from various cereal grains. In commercial brewing, refined wheat starch, potato starch, and corn starch have been used. Corn starches, in particular, are used in the production of glucose syrups. Wheat starch is used in breweries in Australia and Canada due to local economic conditions. However, corn is the most important source of refined starch.
Types of Cereal Adjuncts
Corn products have traditionally been the preferred adjunct among brewers. They are highly consistent in terms of quality, composition, and availability. They produce a range of fermentable sugars and dextrins similar to those produced by malt through enzymatic conversion. All corn-derived adjuncts contain some amount of oil, but this generally does not negatively affect the final beer.
Rice is currently the second most widely used adjunct in the United States for producing light-colored lager beers. Rice has a neutral taste, which is seen as a positive characteristic because it does not interfere with the basic malt character of the beer. It contributes to dry, crisp, and snappy flavors and is used in several premium brands, including Budweiser. Some brewers prefer rice because it has lower oil content compared to corn grits. One disadvantage of using rice is that an additional cooking vessel is needed because its gelatinization temperature is too high for proper starch breakdown during normal mashing.
Unmalted barley adds a rich, smooth, “grainy” flavor to beer. Unlike other adjuncts, unmalted barley contributes to foam (head) retention in the finished beer due to lower levels of proteolysis. However, the nitrogenous and complex proteins that contribute to head retention can also cause chill haze problems.
Unmalted wheat is often used as an adjunct to enhance head retention and foam stability in beer. It also contributes to the body or “palate fullness” of the beer. Its high protein content greatly enhances foam stability. Beers made with significant amounts of wheat adjuncts tend to have a light flavor and smooth taste. Wheat adjuncts are used in the same way as barley adjuncts, but unlike barley, wheat has almost no husk, so tannins are not a significant issue. The gelatinization temperature range for wheat is between 52 and 64°C.
The high protein, fat, and oil content of oats theoretically make them unsuitable for brewing. However, oats have been used in the brewing process, particularly in brewing oatmeal stout.