Un‐malted barley will contribute to foam (head) retention in the finished beer. However, it also contributes to chill haze. Used in Guinness Stout but its clarity problems make it inappropriate for light beers. Flaked barley should be gelatinized at low mash temperature to ensure complete conversion during the mashing process. Barley has a significant amount of vegetable gum and can inhibit runoff during lautering and sparging.
Fermentables that are derived from corn starch will theoretically provide a neutral flavor to the beer. Its use will lighten the body and flavor of the finished beer. Regular corn starch is the easiest form of corn to use (usually the most expensive). It is easily converted in the mash without precooking. Flaked corn (not the breakfast cereals that have other ingredients added) can also be easily utilized in the mash. If corn grits are used, they must be boiled in water for 30 minutes. After gelatinization, the starches may be added to the mash.
One of the most common adjuncts used by the commercial breweries, it offers a clean source of fermentables, neutral flavor and body lighteners. Whole white rice must be ground into small granules before cooking. It is absolutely necessary to cook the rice for 30 minutes in boiling water in order to gelatinize it.
Both malted wheat and un‐malted wheat are used in the brewing process. Malted wheat can be milled and added to the mash grist in the same manner as malted barley. Because it is low in enzymes, un-malted wheat in any form must be mashed with malted barley of high enzymatic power. Un‐malted wheat in the form of wheat flakes or wheat flour is often used to economize, enhance head retention / foam stability, and lighten flavor & body. Flaked & torrified wheat in addition to wheat flour can be added directly to the mash. These forms of wheat are already gelatinized or will gelate at mash temperatures and don’t need precooking in order that protein and starch conversion be assured during the mashing process. Some chill haze problems may result from wheat use, also, large amounts will inhibit runoff during sparging. Fred Eckhart recommended the soaking of raw wheat grains in water for 30 minutes before grinding in order to enhance the grinding process.