When it is dried at a low temperature, the gluten is called "undevitalized," or natural-gum gluten. This dried product, when water is added, reverts to the natural gumlike gluten and is, therefore, suitable for fortifying low-protein flour for bread making or use in other food products. Gluten dried at temperatures substantially higher than 112 F. yields a product that does not become gummy upon the addition of water. Such a product is suitable for raising the protein content of foods in which the properties of an "undevitalized" gluten are not needed or wanted. Devitalized gluten is also useful for making high-protein stock feed and industrial products.

The chief industrial use of wheat gluten now is as a raw material for making monosodium glutamate. Heating the wheat gluten with strong hydrochloric acid breaks down the proteins into amino acids. Glutamic acid is recovered from the mixture of amino acids by crystallization and then converted into the monosodium salt, a product that gives a meatlike flavor to foods.

The batter process can be applied to flours from practically all types of wheat except those whose protein content is less than 7 to 8 percent. Its advantages lie in the speed and simplicity of operation, the fact that no chemicals are required, and the practically complete recovery of the wheat gluten in an undevitalized state. The process is especially valuable for making non-highly-refined glucose sirup because there is no loss of dry substance. Typical yields from 100 pounds of dry wheat flour containing 12 percent protein are 100 to 104 pounds of glucose sirup and 12 pounds of dry gluten having a protein content of 80 to 85 percent.

Many commercial organizations have tested the batter process on a pilot-plant scale; several have installed equipment to produce sweetening agents, industrial alcohol, and wheat gluten. Recent annual-production rates have been : Dextrose sugar and glucose sirup, 150 to 200 million pounds; devitalized wheat gluten, 20 to 30 million pounds; and' several million gallons of industrial alcohol. The production varies because some producers depend upon alternate sources of raw material for starch.

The process developed at the laboratory for producing wheat starch from the whole wheat kernel is analogous to that used in the wet milling of corn. Indeed, with only minor alterations in equipment and operating procedure the process can be conducted in corn wet-milling plants. The starch obtained from sound wheat is of excellent quality. It may be converted to sirups and sugar by the same methods used in the conversion of cornstarch. Good starch can be extracted from damaged wheat that otherwise is unsuitable for use as food or feed.

The wheat is steeped in water that contains sulfur dioxide. This steep water, maintained at a temperature of 100 F., is circulated over the wheat for about 15 hours. Corn, on the other hand, is steeped at a temperature of 130 F. for about 40 hours. The lower temperature for wheat is necessary in order to avoid any gelatinization of the starch, but even at the low temperature the grain is softened sufficiently in a much shorter time. At the end of the steeping period the steep water is allowed to drain from the grain. It contains soluble materials that have been extracted from the wheat and is concentrated in a multiple-effect evaporator. The resulting sirup is used later in preparing a byproduct cattle feed.

The steeped wheat is ground in a buhrstone mill with water, which serves as a lubricant. In the pilot plant the slurry from the buhrstone mill is screened over a 26-mesh stainless-steel wire gauze to remove coarse fibers; the material that passes through is screened over No. 17 standard silk bolting cloth to remove the fine fibers. The fiber fractions are washed twice in order to remove additional starch. The washings are combined with the suspension of starch and gluten that passed through the screens, and the combined liquor is known as mill starch. Both fiber fractions are utilized in the preparation of feed. As the process has been conducted in two corn wet-milling plants, the ground wheat has been passed through the regular mill-house equipment for the production of coarse fibers, fine fibers, and mill starch. The coarse fibers are squeezed in a mechanical press to reduce their moisture content to 74 percent, and the slurry of fine fibers is filtered through a filter press to give a cake containing 72 percent water.

The mill starch is a suspension of starch and gluten in water. The starch is heavier than the gluten and to separate them the slurry is allowed to flow over starch tables. The pitch of the table and the rate at which the Mill starch flows over it are such that the bulk of the starch settles out and practically all of the gluten is carried over the end of the table in suspension. The starch is flushed from the table with water, and the resulting slurry is screened through No. 17 standard silk bolting cloth to remove small quantities of fiber and foreign material. The slurry is then filtered, and the starch is washed two or three times with fresh water. If the starch is to be marketed as such, it is dried; but this is unnecessary if it is to be converted into sirup or sugar.

The gluten slurry that flows over the end of the table is allowed to settle and the clear supernatant liquid is drawn off. Part of the clear liquor is used in preparing steep water for processing fresh grain, and the remainder is used as process water for washing the fiber fractions. The thick gluten slurry is centrifuged to recover the suspended gluten for use in preparing feed; and the clear liquor is used as process water. The sirup produced by evaporating the steep water is combined with the fiber fractions and the gluten, and the mixture is dried for the production of a byproduct feed of excellent quality.