The miller, in order to produce flour (which will make the white loaf, so sightly to many), in the process of grinding wheat has been forced to remove the inner bran coats, so rich in mineral matter, and much of the gluten intimately connected with them.
A grain of wheat consists of (1) an outer covering or husk, which is always removed before milling; (2) bran coats, which contain mineral matter; (3) gluten, the proteid matter and fat; and (4) starch, the centre and largest part of the grain. Wheat is distinguished as white and hard, or red and soft. The former is known as winter wheat, having been sown in the fall, and living through the winter; the latter is known as spring wheat, having been sown in the spring. From winter wheat, pastry flour, sometimes called St. Louis, is made; from spring wheat, bread flour, also called Haxall. St. Louis flour takes its name from the old process of grinding; Haxall, from the name of the inventor of the new process. All flours are now milled by the same process. For difference in composition of wheat flours, consult table in Chapter VI. on Cereals.
Wheat is milled for converting into flour by processes producing essentially the same results, all requiring cleansing, grinding, and bolting. Entire wheat flour has only the outer husk removed, the remainder of the kernel being finely ground. Graham flour, confounded with entire wheat, is too often found to be an inferior flour, mixed with coarse bran.
In low milling process, grooved stones are employed for grinding. The stones are inclosed in a metal case, and provision is made within case for passage of air to prevent wheat from becoming overheated. The lower stone being permanently fixed, the upper stone being so balanced above it that grooves may exactly correspond, when upper stone rotates, sharp edges of grooves meet each other, and operate like a pair of scissors. By this process flour is made ready for bolting by one grinding.
In high milling process, grooved stones are employed, but are kept so far apart that at first the wheat is only bruised, and a series of grindings and siftings is necessary. This process is applicable only to the hardest wheats, and is partially supplanted by roller-milling.
In roller milling, wheat is subjected to action of a pair of steel or chilled-iron horizontal rollers, having toothed surfaces. They revolve in opposite directions, at different rates of speed, and have a cutting action.
“The disintegrator consists of a pair of circular metal disks, set face to face, studded with circles of projecting bars so arranged that circles of bars on one disk alternate with those of the other. The disks are mounted on the same centre, and so closely set to one another that projecting bars of one disk come quite close to plane surface of the other. They are inclosed within an external casing. The disks are caused to rotate in opposite directions with great rapidity, and the grain is almost instantaneously reduced to a powder.”
In buying flour, whether bread or pastry, select the best kept by the grocer with whom you trade. Some of the well-known brands of bread flour are Swan’s Down, Bridal Veil, Columbia, Washburn’s Extra, and Pillsbury’s Best; of pastry, Best St. Louis. Bread flour should be used in all cases where yeast is called for, with few exceptions; in other cases, pastry flour. The difference between bread and pastry flour may be readily determined. Take bread flour in the hand, close hand tightly, then open, and flour will not keep in shape; if allowed to pass through fingers it will feel slightly granular. Take pastry flour in the hand, close hand tightly, open, and flour will be in shape, having impression of the lines of the hand, and feeling soft and velvety to touch. Flour should always be sifted before measuring.
Entire wheat flour differs from ordinary flour, inasmuch as it contains all the gluten found in wheat, the outer husk of kernels only being removed, the remainder ground to different degrees of fineness and left unbolted. Such flours are sold by the different health-food companies, who have agencies in the large cities. Franklin Mills flour is included in this class.
Gluten, the proteid of wheat, is a gray, tough, elastic substance, insoluble in water. On account of its great power of expansion, it holds the gas developed in bread dough by fermentation, which otherwise would escape.