ABSORBENT QUALITIES OF FLOUR.
It has long been known that flour gains in weight on being made up into bread. The English act of Parliament allowed 280 lbs. (a sack) of flour to make 320 lbs. of bread. But in fact it makes a much greater weight than this. The average per cent. of water, in English flour, naturally, according to Johnson, is 15 per cent. But good English and French wheat bread, according to the same author, contains 44 per cent. of water; i. e. twenty-eight pounds are absorbed in making. By this estimate, 280 lbs. would gain nearly seventy four pounds, while the act of Parliament allows only forty pounds.
It is understood that American wheat absorbs more water than English; and that United States southern wheat, absorbs more than northern. It is also true that good wheat gains more in baking than poor wheat, and old flour, more than new. It is not good because it takes up water; but good flour has that property, and poor has not; and absorption is, therefore, an evidence of quality.
This absorption of water is in part mechanical and in part chemical. The difference between these may be illustrated; a bushel measure of shelled corn will admit a great quantity of water into its open spaces; it stands between the kernels. When water is thrown upon lime, it does not exist between the particles, but combines with them. Flour absorbs water in both ways.
Absorption, mechanically, depends upon the coarseness of flour, either from the character of its growth, or from the manner of its grinding. The want of light and heat, in unfavorable climates, or in bad seasons, induces sluggish and imperfect action. The juices are but partially digested and assimilated. Many vegetable constituents exist, in consequence, in smaller quantities, or in a crude state. In such cases the texture is porous and spongy. Grinding breaks down the organized form without altering the essential nature of the texture.
It would seem, if this be true, that grain ripened under unfavorable influences would absorb less rather than more water, since the watery particles, from the want of rapid digestion and excretion, remain in the grain. But after grain is cut, and put to dry, a literal evaporation takes place; the water is, in a measure, exhaled.
We are not to suppose that a mechanical absorption predominates. By far the greatest proportion of water is supposed to combine with the ingredients of the flour—starch, gluten, etc.,—chemically. And as flour is rich in starch and gluten, it will have the power of taking water into combination. It has been supposed that the absorbing power of flour depended mainly upon its gluten. But Johnson holds the position in doubt. Whereas, Webster (of England) states that it is with the starch, principally, that water combines. The per cent. of starch, sugar, and gluten, etc., in wheat, depends on the soil and climate;—on the soil, because it must derive from it, originally, the elements of its existence; on climate, because these elements require a certain temperature and quantity of light for their perfect elaboration. It is on this account, that the wheat of southern Europe is better than that of England; that that of Egypt is superior to the Italian. In each case there is a superiority of climate which produces the most perfect elaboration of all the elements of wheat.