Adjuncts are alternative sources of extract used to replace a proportion of the malt. While they may be used as cheaper sources of extract, it is just as likely that they are used to impact some element of product quality such as color (either to darken or lighten it), flavor, or foam. Alternatively their use makes sense if there are prevailing taxation considerations that make low malt use advantageous, for instance, the legislation in Japan that spawned the development of Happoshu and Third Category drinks. See japan.

Liquid adjuncts (sugars/syrups) are usually added in the wort boiling stage. They may be sugars extracted from plants rich in fermentable sugars, notably sucrose from cane or beet. The sucrose may be hydrolyzed by the enzyme invertase to produce its component monosaccharides, glucose and fructose, in the somewhat sweeter “invert” sugar. Alternatively they may be sugars produced in factories by the acid or (more likely these days) enzyme-hydrolysis of starch, especially from corn (maize). By selection of enzyme and processing conditions a range of products can be realized that differ in their composition, notably their degree of fermentability (see table). Liquid adjuncts are frequently called “wort extenders” because they allow an extension of brew house yield through obviating the need for extra milling, mashing, and wort separation capacity.

Solid adjuncts are added in mashing, because they require the enzymes from malt or exogenous enzymes to digest their component macromolecules. Solid adjuncts are based on diverse cereals, notably unmalted barley, wheat, corn, rice, oats, rye, and sorghum. There is also interest in pseudo-cereals such as buckwheat and proso-millet, primarily in the context of beers for people suffering from gluten intolerance.

In turn, solid adjuncts can be in different forms: whole cereal, grits, flour, flakes, torrefied, or malted (in the context of malt that is other than the standard malt used for producing the beer style concerned). There has been some consideration of extrusion cooking of cereals but the resultant products have a very low bulk density and therefore tend to have unfavorable transportation economics. The high gelatinization (“melting”) temperature for corn, rice, and sorghum demands that these cereals require treatment at higher temperatures than barley, oats, rye, or wheat. If such cereal is in the form of grits (produced by the dry milling of cereal in order to remove outer layers and the oil-rich germ), then it needs to be “cooked” in the brew house.

Alternatively the cereal can be pre-processed by intense heat treatment in a micronization operation. The whole grain is conveyed beneath an intense heat source (500°F/260°C), resulting in a “popping” of the kernels (c. f. puffed breakfast cereals) to produce so-called torrefied cereal. In flaking, grits are gelatinized by steam and then rolled between steam-heated rollers. Flakes (like grits and flour) do not need to be milled in the brew house, but micronized (torrefied) cereal does.

Cereal cookers are made of stainless steel (or occasionally copper) and incorporate an agitator and steam jackets. See cereal cooker. The adjunct is delivered from a hopper and the adjunct mixed with water at a rate of perhaps 15 kg/hectoliter of water. The adjunct will be mixed with 10%–20% of malt as a source of enzymes. Following cooking the adjunct mash is likely to be taken to boiling and then mixed with the main mash (that is at a relatively low mashing-in temperature, say 113°F or 45°C), with the resultant effect being a rise in temperature to allow conversion of the starch from the malt. This is called “double mashing.”

While adjuncts are widely derided by beer enthusiasts for their wide use in major beers (to lighten color and flavor), many uses of adjuncts are quite traditional. Indeed the very long-standing use of certain adjuncts in some of the mainstream beers renders their use as being traditional for those beer styles. American colonialists often supplemented the mash with whatever starch was at hand; pumpkin was a particularly popular adjunct. Many Belgian and Belgian-style beers use a form of sucrose called “candi sugar,” which is often caramelized to add color and flavor to beers. See candi sugar. In particular, dark candi sugar, usually in the form of a heavy syrup, gives many dark Belgian-style beers distinctive raisin-like caramel flavors. These sugars, frequently used as up to 20% of extract, are highly fermentable and can help beers attain very low residual sugar profiles. Craft brewers use various sugars to attain high gravities in beer styles such as barley wine, “double IPA,” and other strong ales. Honey is another popular adjunct, and may be added in the kettle. Honey is also often added post-fermentation, where it adds sweetness and honey aromatics.