|
|
13. MILLING OF WHEAT FLOUR.
|
| Tuesday, April 28, 2009 |
Great advances have been made in the production of flour from wheat, and these are very good evidence of man's progress in the way of invention. The earliest method consisted in crushing the grain by hand between two stones, and from this crude device came the mortar and pestle. A little later millstones in the form of thick, heavy disks were brought into use for grinding grain.
Two of these stones were placed so that their surfaces came together, the lower one
being stationary and the upper one made to revolve. Early grinding apparatus of this kind was turned by human power, but this kind of power was first displaced by domestic animals and later by wind and water. Out of this arrangement, which is still used to some extent in small mills, has grown the present-day complicated machinery of the roller process, by which any part of the grain may be included or rejected.
14. In the roller process, the grain is crushed between metal rolls instead of being ground between stones. It is first screened in order to separate all foreign matter from it, and then stored in bins. When it is taken from these receptacles, it is put through another cleaning process, called scouring, or it is thoroughly washed and dried in order to loosen the dirt that clings to it and to free it entirely from dust, lint, etc.
As soon as it is completely cleansed, it is softened by heat and moisture and then passed
through a set of corrugated rollers, which are adjustable as are the rubber rollers of a clothes wringer and which flatten and break the grains.
After this first crushing, some of the bran is sifted out, while the main portion of the grain is put through another set of rollers and crushed more finely. During the milling, these processes of crushing the grain and removing the bran are repeated from six to nine times, each pair of rollers being set somewhat closer than the pair before, until the grain is pulverized.
After the grain has been thus reduced to a powder, it is passed through bolting cloth, which acts as a very fine sieve and separates from it any foreign material that may remain. The result is a very fine, white flour.
15. GRAHAM FLOUR.
--Sometimes the entire grain, including the bran, germ, etc., is ground fine enough merely for baking purposes and is used as flour in this form. Such flour is called graham flour. It
contains all the nutriment, mineral matter, and cellulose of the original grain, and is therefore considered valuable as food. However, the objection to this kind of flour is that its keeping quality is not so good as that of the kinds from which the germ has been removed, because the fat contained in the germ is liable to become rancid. |
posted by neptunus @ 6:39 PM
 |
|
|
|
|
Post a Comment