7. Grains Used for Flour.--As has been pointed out elsewhere, numerous
grains are raised by man, but only two of them, namely, wheat and rye,
are used alone for the making of yeast, or leavened, bread. The other
grains, such as corn, rice, and oats, produce a flat, unleavened cake,
so they are seldom used for bread making unless they are mixed with
white flour. Wheat and rye have been used for bread making for a very
long time, and their universal use today is due to the fact that they
contain considerable protein in the form of _gluten_. This is the
substance that produces elasticity in the dough mixture, a condition
that is absolutely essential in the making of raised bread. In fact, the
toughness and elasticity of bread dough are what make it possible for
the dough to catch and hold air and gas and thus produce a light,
porous loaf.
8. Of these two grains, rye is used less extensively in the United
States for the making of bread than wheat, although in some countries,
particularly the inland countries of Continental Europe, considerable
use is made of it. Its limited use here is undoubtedly due to the fact
that when rye is used alone it makes a moist, sticky bread, which is
considered undesirable by most persons. The reason for this is that,
although rye contains a sufficient quantity of gluten, this substance is
not of the proper quality to make the elastic dough that produces a
light, spongy loaf. Therefore, when rye is used, wheat flour is
generally mixed with it. The result is a bread having a good texture,
but the dark color and the typical flavor that rye produces.
9. Wheat, the other grain used for bread making, is an annual grass of
unknown origin. It is used more extensively for food than any other
grain. In fact, it has been estimated that the average quantity consumed
by each person is about 6 bushels a year, and of this amount by far the
greater part is used in the making of bread. Since so much of this grain
is used as food, considerable time and effort have been spent in
developing those qualities which are most desirable for the purpose to
which wheat is put and in perfecting the processes whereby wheat flour
of a good quality may be obtained.
This grain is particularly well adapted for bread making because of the
nature of the proteins it contains and the relative proportions of
these. These proteins, which occur in the wheat grain in the form of
gluten, are known as _gliadin_ and _glutenin_. The gliadin imparts
elasticity and tenacity, or toughness, to the gluten, and the glutenin
gives it strength. It is not, however, so much the quantity of gluten in
the wheat grain that actually determines the quality of flour as the
fact that the two varieties must be present in the proper proportions
in order for the gluten to have the properties desired for bread making.
Wheat consists of numerous varieties, but only two of these are grown
and used in the United States, namely, _spring_, or _hard, wheat_ and
_winter_, or _soft, wheat_.
10. SPRING, OR HARD WHEAT is so named because it is sown in the spring
of the year and is very tough or firm. Before this variety was known,
the wheat used for bread making was not ideal, and the efforts that were
made to produce a grain that would be suitable for this purpose resulted
in this variety. To obtain its particular composition, spring wheat must
be grown under suitable climatic and soil conditions. In North America,
it grows in the north central part of the United States and along the
southern border of Canada. This variety, which is harvested in the late
summer, is characterized by a large proportion of gluten and a
correspondingly small amount of starch. It is the presence of the gluten
that accounts for the hardness of the spring-wheat grain and the tough,
elastic quality of the dough made from the spring-wheat flour. Bread
dough, to be right, must have this quality, so that the flour made from
spring wheat is used almost exclusively for bread; whereas, for cake and
pastry, which should have a tender, unelastic texture, flour made from
soft wheat is more satisfactory.
11. WINTER, OR SOFT WHEAT derives its name from the fact that it is
planted in the autumn and is soft in texture. It is of less importance
in the making of bread than spring, or hard, wheat, but it is the kind
that has been grown for centuries and from which the varieties of spring
wheat have been cultivated. It is a softer grain than spring wheat,
because it contains less gluten and more starch. The flour made from it
does not produce so elastic a dough mixture as does that made from the
other variety of wheat; consequently, the finished product, such as
bread, rolls, etc., is likely to be more tender and more friable, or
crumbly. It is for this reason that winter, or soft, wheat is not used
extensively for bread, but is employed for pastry flour or mixed with
spring wheat to make what is called a _blend flour_, which may be used
for all purposes.
12. STRUCTURE OF WHEAT GRAIN.--In its natural state, wheat contains all
the food substances required for the nourishment of the human body in
nearly the proper proportions, and in addition it has in its
composition sufficient cellulose to give it considerable bulk. It has
been estimated that the average composition of this grain is as follows:
PER CENT.
Protein...................................... 11.9
Fat.......................................... 2.1
Carbohydrates................................ 71.9
Mineral salts................................. 1.8
Water........................................ 10.5
Cellulose..................................... 1.8
Total....................................... 100.0
[Illustration: Fig. 1]
So that the composition of wheat and the making of wheat flour may be
more clearly understood, it will be well to observe the structure of a
grain, or kernel, of wheat, which is shown greatly enlarged in Fig. 1.
At _a_ is shown the germ of the young plant, which remains undeveloped
until the grain is planted. This part contains practically all the fat
found in the grain, some starch, and a small quantity of protein. At _b_
is shown the inside of the kernel, or the _endosperm_, as it is called,
which is composed of starch granules interlaced with protein and mineral
salts. Surrounding these, as at _c_, is a layer of coarse cells that
contain mineral matter and protein, and between these cells and the
outer husk, as at _d, e, f_, and _g_, are layers of bran, which are
composed of cellulose and contain mineral salts and small quantities of
starch and protein. Enveloping the entire kernel is a husk, or bran
covering, _h_. This forms a protection to the rest of the grain, but it
cannot be used as food, because it is composed almost entirely of
cellulose, which is practically indigestible. The center of the grain,
or the heart, is the softest part and consists of cells filled with
starch. From this soft center the contents of the grain gradually grow
harder toward the outside, the harder part and that containing the most
gluten occurring next to the bran covering.
13. MILLING OF WHEAT FLOUR.--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.
16. WHOLE-WHEAT FLOUR.--The best grades of fine white flour make bread
of excellent quality, but such bread is not so nutritious as that made
from whole-wheat flour. In the making of this kind of flour, some of the
choicest varieties of wheat are first moistened in order to soften the
woody fiber of the bran and are then sifted until the outer husk of the
grain is removed. After this treatment, the grains are dried and then
pulverized into various grades of so-called whole-wheat flour. The name
whole-wheat flour is misleading, because it implies that all of the
grain is used; whereas, since several of the outer layers of bran and
the germ are removed in its production, whole-wheat flour is merely
flour in which practically all the gluten and the starch are retained.
Because this variety is not sifted as are the white flours, it is not so
fine as they are; but it is not so coarse as graham flour, nor is bread
made from it so dark in color. Both graham and whole-wheat flours
produce a more wholesome bread than any of the varieties of white flour,
because they contain more of the nutritive elements and mineral salts,
which are necessary in the diet. The bran that is retained in them is
not used by the body as food, but it adds bulk to the diet and assists
in carrying on the normal functions of the digestive tract.
17. SELECTION OF FLOUR.--If a large quantity of flour must be bought at
one time, as, for instance, enough to last through an entire season, it
is advisable to test it carefully before the purchase is made, so as to
avoid the danger of getting a poor grade. As a rule, however, housewives
are obliged to purchase only a small quantity at a time. In such cases,
it will not be necessary to test the flour before purchasing it,
provided a standard make is selected. Very often, too, a housewife in a
small family finds it inconvenient to keep on hand a supply of both
bread flour and pastry flour. In such an event, a blend flour, which, as
has been mentioned, is a mixture of flour made from spring and winter
wheat that will do for all purposes, is the kind to purchase. While such
flour is not ideal for either bread or pastry, it serves the purpose of
both very well.
18. QUALITY OF FLOUR.--Flour is put on the market in various grades, and
is named according to its quality. The highest grade, or best quality,
is called _high-grade patent_; the next grade, _bakers'_; and the next,
_second-grade patent_. The lowest grade, or poorest quality, is called
_red dog_. This grade is seldom sold for food purposes, but it is used
considerably for the making of paste.
The quality of flour used in bread making is of very great importance,
because flour of poor quality will not, of course, make good bread.
Every housewife should therefore be familiar with the characteristics of
good flour and should buy accordingly.
19. Several tests can be applied to flour to determine its kind and its
quality. The first test is its color. Bread flour, or flour made from
spring wheat, is usually of a creamy-white color, while pastry flour, or
that made from winter wheat, is more nearly pure white in color. A dark,
chalky-white, or gray color indicates that the flour is poor in quality.
The second test is the feel of the flour. A pinch of good bread flour,
when rubbed lightly between the thumb and the index finger, will be
found to be rather coarse and the particles will feel sharp and gritty.
When good pastry flour is treated in the same way, it will feel smooth
and powdery. The third test is its adhering power. When squeezed tightly
in the hand, good bread flour holds together in a mass and retains
slightly the impression of the fingers; poor bread flour treated in the
same way either does not retain its shape or, provided it contains too
much moisture, is liable to make a damp, hard lump. The odor of flour
might also be considered a test. Flour must not have a musty odor nor
any other odor foreign to the normal, rather nutty flavor that is
characteristic of flour.
The bleaching and adulteration of flour are governed by the United
States laws. Bleaching is permitted only when it does not reduce the
quality or strength nor conceal any damage or inferiority. Such flour
must be plainly labeled to show that it has been bleached.
20. CARE OF FLOUR.--There is considerable economy in buying flour in
large quantities, but unless an adequate storing place can be secured,
it is advisable to buy only small amounts at a time. Flour absorbs odors
very readily, so that when it is not bought in barrels it should if
possible be purchased in moisture-proof bags. Then, after it is
purchased, it should be kept where it will remain dry and will not be
accessible to odors, for unless the storage conditions are favorable, it
will soon acquire an offensive odor and become unfit for use. Flour
sometimes becomes infested with weevils, or beetles, whose presence can
be detected by little webs. To prevent the entrance of insects and
vermin of all kinds, flour should be kept in tightly closed bins after
it is taken from the barrels or sacks in which it is purchased. If newly
purchased flour is found to be contaminated with such insects, it should
be returned to the dealer.