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.