Experimental cookery

Tempering consists of adding a definite amount of water at a certain temperature to wheat berries, the proportion of water added depending on the moisture content of the wheat and other factors such as relative plumpness and hardness of the kernels. In tempering wheat the water is usually not left in contact with the wheat long enough for moisture to be absorbed by the endosperm. Thus the pliableness and toughness of the bran coats are increased so that they are more easily separated from the endo- sperm. Sometimes, to prevent the endosperm from breaking into very fine particles, the water is added in two portions, part of the first addition being absorbed by the endosperm. The germ because of its high fat content is easily flattened or flaked and is removed by bolting from the other constituents of the wheat berry during milling. The endosperm constitutes about 80 per cent of the wheat berry. The starch is more concentrated in the immediate vicinity of the germ and in the interior of the endosperm. The concentration becomes less and less towards the outer layers of the wheat berry. The starchy endosperm being drier and more friable tends to shatter more readily when the berries are fractured or broken between rollers. In the first breaks, the wheat kernels are mostly broken into large frag- ments by the corrugated rollers. The coarser fragments, which are sepa- rated from the finer ones by sifting, are returned to the next set of break rolls of which there are 5 or 6. Other things being equal, a larger pro- portion of fine particles is obtained from soft wheat than from hard wheat during the first breaks. Bolting or sifting, which occurs after each break, is the separation of the coarse particles, which are reground, fine granules of flour, which are not reground, and intermediate particles, which are sent to the purifier. Purifying refers to a part of the milling process whereby particles pass over a sloping, vibrating sieve. At the entrance the meshes of the sieve are fine but gradually increase in size to the discharge end. As the particles travel down this sieve they are separated according to size. During this process controlled air currents lift out the flakier and more fibrous particles. The remainder of the particles, known as purified middlings because they are freer from branny, fibrous material, yield a more highly refined flour after reduction. 394 FLOUR AND BREAD The purified middlings are ground between smooth iron rollers to re- duce them to the desired fineness. Since the flour bolted from the first grinding of any stream of purified middlings is more highly refined, be- cause it is freer of fiber than that produced by subsequent grinding of the coarser residues, it is often used in making the so-called "short" patent flours.