CEREAL FOODS.
BARLEY (GENUS _Hordeum_).
In the United States barley is not used to any extent as human food.
It has all the nutritive properties of the common cereals and may be
considered as a food product, although its chief use is in the making
of fermented beverages which will be described in full in the second
volume.
Barley is cultivated chiefly in the northern and western portions of
the United States and is similar to the oat in this respect, that when
the grain is threshed by the ordinary process the first layer of chaff
is not separated, and, therefore, it goes into the market unhulled.
There are varieties of naked barley which are not much cultivated. The
cultivated varieties (_Hordeum sativum_ Pers.) belong practically to
one species, although there are very many different varieties grown.
The character of barley best suited to malting will be discussed in the
second volume.
_Acreage and Yield of Barley._--The area planted to barley in the
United States and other statistical data relating thereto for the year
1906 are as follows:
Acreage, 6,323,757
Yield per acre, 28.3 bushels
Total production, 178,916,484 „
Price per bushel, 41.5 cents
Value of crop, 74,235,997 dollars
=Composition of a Typical Unhulled Barley.=--From a comparative study
of a number of samples of American barley the following numbers are
regarded as typical of the composition of the unhulled barley grown in
the United States:
Weight of 100 kernels, 4.53 grams
Moisture, 10.85 percent
Protein, 11.00 „
Ether extract, 2.25 „
Crude fiber, 3.85 „
Ash, 2.50 „
Starch and sugar, etc., 69.55 „
The important points brought out in the above data are that the
percentage of fiber in the unhulled barley is less than one-half that
of the unhulled oat, as stated further on, while the percentage of
ether extract is only about one-half that of the unhulled oat, and the
protein is also decidedly less than in the whole oat.
As has been stated, barley is not very generally used in this country
for human food, but is used in this and other countries as an
ingredient of soup.
[Illustration: FIG. 22.--BARLEY STARCH. × 200.--(_Bureau of
Chemistry._)]
=Protein of Barley.=--The following protein compounds are found in
barley in proportionate weight to the total weight of the seed:
Leucosin, 0.30 percent
Hordein, 4.00 „
Edestin, 1.95 „
Proteose, 1.95 „
Insoluble protein, 4.50 „
As seen from the above table the most important of the soluble proteins
is hordein, which in quantity is almost equal to the insoluble protein
of the barley grain. The starch granules of barley are recognized by
their distinctive shape and size, as revealed by the microscope. A
typical microphotographic view of barley starch is shown in Fig. 22.
BUCKWHEAT (_Polygonum fagopyrum_ L.).
=Buckwheat= is usually classed with the cereals, but botanically it
does not belong to the order of true grasses to which the cereals
belong.
Buckwheat is commonly grown in many parts of the United States, and its
seed is highly prized for bread and cake making purposes. The buckwheat
is ground and the outer black tough hull separated, and the flour is
used chiefly for making hot breakfast cakes which are much prized
throughout the country. Properly ground buckwheat flour has a more
or less dark tint, due to fine particles of the outer envelope which
escape the bolting process.
_Acreage and Yield of Buckwheat._--This crop is not grown in many
states. New York, Pennsylvania, and Michigan produce the largest
quantities. The statistical data for buckwheat grown in the United
States in 1906 are as follows:
Acreage, 789,208
Yield per acre, 18.6 bushels
Production, 14,641,937 „
Price per bushel, 59.6 cents
Total value, 8,727,443 dollars
=Composition of Buckwheat Flour.=--The composition of finely bolted
buckwheat flour is as follows:
Moisture, 11.89 percent
Protein, 8.75 „
Ether extract, 1.58 „
Ash, 1.85 „
Fiber, .52 „
Starch and sugar, 75.41 „
Calories per gram, 3,854
The above is the composition of a white flour more finely ground and
bolted than is advisable for palatable purposes. In the grinding of the
above flour the germ which contains a greater part of ether extract is
eliminated and also a large quantity of the bodies rich in protein.
The composition of a less highly refined flour and one which is more
palatable and more nutritious is given in the following data:
Moisture, 11.19 percent
Protein, 9.81 „
Ether extract, 2.33 „
Ash, 1.53 „
Fiber, .73 „
Starch and sugar, 74.41 „
Calories per gram, 3,954
=Milling Process.=--In the preparation of the so-called highest grade
of buckwheat flour, that is, that which is most carefully ground and
thoroughly bolted, the process employed is as follows: During the
process of milling the buckwheat grains pass to a receiving separator
which removes all the coarse particles, stones, straws, etc., by means
of a series of sieves. At the same time any dust which they contain
is blown out by a current of air. The sifted grains pass next to the
scouring machines, in which they are thoroughly scoured, cleaned, and
polished. From these machines the grains pass to a separator containing
magnets, by means of which any pieces of metal, in the form of nails,
screws, pieces of wire, etc., are removed.
The grains next pass through a steam dryer for removing the greater
portion of the water employed for the scouring. As soon as they are dry
they are again treated to a blast of air, which removes any dirt, dust,
or light particles which may have been detached during the process of
drying. The grains next pass to the shelling rolls, where the greater
part of the outer hulls is removed. This process is accomplished by
means of an apparatus which is called a sieve scalper. After the
separation of the outer hulls the residue of the material passes to
a drying chamber, where the moisture is reduced to about 10 percent,
thus insuring the keeping qualities of the flour. After drying the
grains are ready for the rolls. After entering the rolls the process
is practically the same as that which is employed in milling wheat,
consisting of a series of breaks and reductions, with the attendant
bolting and grading, and this process is prolonged until the flour is
practically removed from the feed or middlings. The sifting cloths used
in the bolting of buckwheat flour are somewhat coarser than those for
wheat, and this allows some of the dark particles of the inner hulls
to pass into the flour, which gives it a dark color on baking. It is
quite possible to make a buckwheat flour as white as that from wheat,
but in this country the public taste requires a darker product, so
that the white flour does not readily sell. The requisite degree of
darkness is secured by using bolting cloths which will allow a part
of the inner hulls (middlings) to pass into the flour. Two grades of
flour are generally produced--a whiter one in which finer cloths are
used, and a darker flour made by using coarser bolting cloths, allowing
larger quantities of middlings to pass through. The outer hulls which
are first removed are used for fuel, although from their composition it
is seen that they contain a large quantity of carbohydrates and might
be very profitably used in connection with some highly nitrogenous
food, such as cottonseed meal or flaxseed meal for feeding cattle.
The middlings are used principally as cattle food, and especially by
dairymen.
The above process, while it makes a white and fine-looking flour, is
not to be compared with the meal made in the old-fashioned way of
grinding between stones and separating the principal part of the outer
hull by bolting. This old-fashioned flour is more nutritious, that is,
it contains more fat and protein, has a greater fuel value, or in other
words has a greater number of calories and makes a much more palatable
cake than the fine modern flour.
=Buckwheat Cakes.=--Buckwheat cakes are prepared from batter made by
mixing buckwheat flour into a paste of the proper consistency, seeding
it with yeast, and allowing it to remain in a moderately warm place
until fermentation takes place. The proteins of buckwheat have some
agglutinating power, and thus, when treated as above, make a cake
capable of a considerable degree of aeration. Baking powders are
often used as a substitute for yeast and permit of preparation in a
few minutes instead of waiting for the fermentation above mentioned.
The product made in this way cannot be considered so palatable or
nutritious as the old-fashioned product. The batter is baked on a
smooth hot iron or soapstone, polished and kept bright in order to
prevent the sticking of the cake. The proper polishing of the iron is
a better means of preventing sticking than greasing. The batter is
poured over the smooth iron and is of a consistency to flatten out
without help and to form a film over the baking iron, which produces a
cake about one-fourth of an inch in thickness. The cake is to be turned
as soon as the side in contact with the iron is brown. It is evident
that in this baking process there can be no very profound change in
the starch granules, but this does not appear to materially interfere
with the digestibility of the product. Buckwheat cakes are eaten hot,
usually with butter and sirup. Maple sirup, sorghum sirup, or cane
sirup in a pure state are highly prized for use with buckwheat cakes.
These sirups are both condimental and nutritious. Mixed sirups made
of glucose, melted brown sugar, or molasses, or mixtures of all these
bodies are more commonly furnished to the consumer than the pure sirup
mentioned above. Honey is also used very extensively as a condimental
flavor for cakes of this kind.
=Adulterations.=--There is probably no bread or cake making material
which is subjected to more extensive adulteration than buckwheat flour.
Much of what is sold as buckwheat flour may be regarded as imitations
of that substance. Mixtures of rye flour, Indian corn flour, wheat
flour, and other ground cereals are used as a substitute for buckwheat.
There can be no objection from the hygienic point of view to such
substitutes but the use of these mixtures under the name of buckwheat
can be regarded in no other light than as an unpardonable fraud.
=Detection of Adulterations.=--There is rarely any mineral adulteration
practiced with buckwheat flour and if so it is easily detected by
incineration. Any content of ash, unless baking powder has been
used, above 2 percent may be regarded with suspicion as indicating
an admixture of some mineral substance. The cereal flours used for
adulteration are readily detected by the microscope in the hands of
an experienced observer. The field of the microscope has only to be
compared with the microscopic appearance of genuine buckwheat starch in
order to detect the added substance.
=Buckwheat Starch.=--The microscopic appearance of buckwheat starch
is shown in the accompanying figure. The granules of buckwheat starch
are very characteristic. They consist of chains or groups of more or
less angular granules with a well defined nucleus, and without rings or
with very faint rings. The contour of buckwheat starch is more angular
than that of any other common cereal with exception of maize and rice,
and it is this and the relative size which enable the observer to
distinguish it from other starches. The size of the granules is quite
uniform, varying usually only from 10 to 15 microns[23] in diameter. In
so far as the angular appearance is concerned the granules of buckwheat
starch have a general resemblance to that of maize and rice and oats,
but a comparison under the microscope of the three starches reveals
lines of distinction which with a little practice would prevent the
observer from drawing a false conclusion.
[23] A micron is one thousandth of a millimeter.
[Illustration: FIG. 23.--BUCKWHEAT STARCH. × 200.--(_Courtesy of Bureau
of Chemistry._)]
INDIAN CORN (_Zea mays_).
Next to wheat the most important cereal used as a human food in the
United States is Indian corn. According to the magnitude of the crop,
Indian corn is the leading cereal of the country. Statistical data on
the production of Indian corn in the United States during 1906 are
given in the following table:
Acreage, 96,737,581
Yield per acre, 30.3 bushels
Production, 2,927,416,091 „
Value per bushel, 39.9 cents
Total value, 1,166,626,479 dollars
=Indian corn= is universally employed as food throughout all parts
of the country, but more especially in the South, where the daily
dietary is rarely complete without one or more meals in which Indian
corn is served in some form or other. Although it is grown much more
extensively in the North than in the South, it is not so generally used
as human food. Indian corn grows in all kinds of soil and produces,
under favorable conditions, large yields in all parts of the country.
It is the most important agricultural crop of many states, namely,
Indiana, Illinois, Iowa, Missouri, and Kansas. It is planted in the
late winter and spring in different parts of the country. The planting
season varies from January in Florida to June in Maine and Minnesota
and the earlier varieties will mature in 120 days.
=Maize= is a crop which requires an abundance of rainfall and a high
temperature during the growing season. Maize is planted in rows about
three and one-half feet apart and in hills of about the same distance
apart, or it may be drilled between the rows so that one stalk grows
a distance of about from nine inches to a foot from its fellows. It
requires constant cultivation during the early period of its growth and
a careful preparation of the seed bed. Good farmers give from four to
seven cultivations to the growing crop. The field must be kept free of
weeds and in good tilth to secure the best results.
Many hundreds of analyses of the maize kernel have been made, but
a combination of them all in the following data may be regarded as
typical of the Indian corn grown in this country.
Weight of 100 kernels, 38 grams
Moisture, 10.75 percent
Ether extract, 4.25 „
Protein, 10.00 „
Fiber, 1.75 „
Ash, 1.50 „
Starch and sugar, etc., 71.75 „
The consideration of the above data shows that Indian corn is a ration
in which the protein is rather low. In other words, the ratio of
protein to the carbohydrates and fat is rather large. It is a food
product which is particularly well suited to furnish heat and energy
and support a high degree of muscular exertion. For this reason it is a
food product which is particularly well adapted to men engaged in hard
manual labor.
=Varieties.=--There are many distinct varieties of Indian corn.
Sturtevant has published a description of several hundred. These
varieties are classified under various subspecies. The polymorphic
species, _Zea mays_, according to Sturtevant, can be divided into a
number of groups which, on account of their well defined and persistent
characters, may be considered as presenting specific claims and may
properly receive specific nomenclature. The grouping adopted is founded
upon the internal structure of the kernel for cultivated varieties, and
the presence of a husk to the kernel in the assumed aboriginal form.
Hence Sturtevant offers the names _Zea tunicata_ for the husk-kernel
forms, _Zea everta_ for the popcorn, _Zea indurata_ for the flint
corns, _Zea indentata_ for the dent corns, _Zea amylacea_ for the soft
corns, and _Zea saccharata_ for the sweet corns.
[Illustration: FIG. 24.--SECTION OF RAW POPCORN. × 150.--(_Courtesy of
Bureau of Chemistry._) Shows cells with the small angular starch grains
closely packed together within them.]
Argument in favor of the specific claims for these groups is based
primarily on the convenience thus attained; secondarily, on the absence
or rarity of intermediate or connecting forms, so far as present data
extend, and also on the antiquity of the separation. It seems almost
certain that in the order of evolution (excluding from consideration
the puzzling sweet corn group) progress has been from the pops, through
the flints and the dents, to the softs. Certainly the soft corns in
some of their varieties present a kernel that is larger, softer, and
less fitted to the struggle with natural conditions than is the kernel
from any of the other groups. Yet soft corns are the prevailing form in
the mummy burials of Peru and of our Southwestern states. The popcorn,
on the contrary, has stronger regerminative powers than have the other
groups, is better fitted to contend against natural vicissitudes, and
is the kind that has been reported as found growing wild in Mexico
under the name of Coyote corn, _Zea canina_ Watts.
Some of these subdivisions may not be accepted by botanists, but they
are convenient for purposes of description. The principal field
varieties which are grown are the flint corn, _Zea indurata_, and the
dent corn, _Zea indentata_.
POPCORN.
This variety of maize is used very largely in the United States as
a delicacy, and with sugar and cream as a dessert. It is a hard,
small-grained variety which has the property, when heated, of exploding
with a very great enlargement of the starch grain, producing a soft and
very delicate edible material which is highly prized.
[Illustration: FIG. 25.--SECTION OF POPCORN IN FIRST STAGE OF POPPING,
SHOWING PARTIALLY EXPANDED STARCH GRAINS AND RUPTURED CELL WALLS. ×
150.--(_Courtesy of Bureau of Chemistry._)]
In the raw popcorn the starch grains are packed together very closely
within the cells. When popping begins there is an expanding of the
starch grains, producing a cavity nearly circular in form in each
grain. This causes a rupturing of the cell walls, though fragments
are plainly visible in the early stages. In the fully expanded or
popped kernel the starch grains have expanded until each is about
half or two-thirds as large as the original cells of the endosperm.
The cell walls in this stage are practically obliterated as far as
detecting in a section is concerned. The exploding of the starch
grains is influenced by the water content of the kernel. It must not
be too wet nor too dry; about 10 or 12 percent is the proper content
of moisture. These changes are beautifully shown in the accompanying
microphotographs, Figs. 24, 25, and 26, by Mr. Howard, of the Bureau of
Chemistry.
[Illustration: FIG. 26.--SECTION OF FULLY POPPED POPCORN. ×
150.--(_Courtesy of Bureau of Chemistry._) The fully expanded starch
grains are nearly half as large as the original cells in which they
were contained.]
SWEET CORN.
This is a variety of maize which develops a high sugar content and
is eaten while the starch is yet soft, in other words, in an unripe
state. It is a food product of immense importance in the United States,
although almost unknown in Europe. The content of sugar varies from
5 to 8 percent in the fresh, soft kernel. The sugar which is present
in the kernel rapidly disappears after the husking or removal from
the stalk. In order to secure the maximum sweetness the corn should
be cooked and eaten as soon as possible after removal from the stalk.
Where it is not possible to do this it should be placed in cold storage
after removal from the stalk and remain unhusked until it is ready for
cooking. Green corn is universally eaten hot. It is usually cooked by
boiling in water, although it may also be roasted before the fire. It
has a high food value, and the composition of the grains of fresh,
soft, green corn is shown in the following table:
_Composition of Fresh Green Indian Corn_:
Moisture, 73.00 percent
Starch, 13.50 „
Sugars, 6.00 „
Protein, 5.00 „
Crude fiber, 1.20 „
Ash, .70 „
Fat, .60 „
=Maize Proteins.=--The proteins of maize are composed principally of
two zeins. The two forms are differentiated by their behavior toward
alcohol. The first form constitutes the zein soluble in alcohol and
the second the zein insoluble in alcohol. There are two other proteins
in maize existing in small quantities which have been named myosin and
vitellin, respectively. There is also a third unnamed variety and small
quantities of albumin.
=Variation in Maize, under Different Climatic Conditions.=--It
is possible that most of the varieties and subvarieties of maize
are simply the existing standard varieties modified by changing
environments. There are certain conditions of climate, soil, and
distribution of rainfall which tend to produce a large, starchy, soft
grain, while other conditions tend to produce a small, hard grain
richer in protein. The variations of importance are those of the
carbohydrates and the protein, which are complementary, since as the
protein rises the carbohydrates fall in relative proportion. There
is also a marked variation in the carbohydrates, due to variety and
climatic conditions combined. It is, for instance, the increase of the
sugar at the expense of the starch that produces the body known as
sweet maize eaten in the green state, as already described. Even in
the sweet variety the relative proportion of sugar varies in different
localities and under different conditions of growth.
=Early Varieties.=--There are certain varieties of maize which are
of especial value on account of their early maturation. This is a
property extremely valuable in the sweet variety of maize or that
eaten in the green state, since it is important to get these varieties
into the market as early as possible and to continue them as long as
possible. This is secured by planting the early variety at as early
date as possible and planting later maturing varieties at intervals
thereafter. By the selection of varieties of different periods of
maturing it is possible in the climate of Washington to offer green
corn from neighboring fields on the market from July until the advent
of a killing frost which is usually the last of October or first of
November. This gives a period of nearly four months during which the
green corn may be delivered to the local market. Further south the
period of supply is longer.
=Canned Corn.=--Immense quantities of green corn are grown for the
purpose of canning in order to supply the market during the closed
season. The canning industry for green corn is located chiefly in the
north. In the eastern states the industry is of great importance, from
Maryland to Maine. The northern-grown corns are often preferred as
they are supposed to be sweeter and more palatable. In the central
western states, northern Indiana, Michigan, Wisconsin, northern
Illinois, and Iowa are the principal centers of the canning industry,
although it is practised to a greater or less extent in almost all
parts of the country.
=Adulterations of Canned Corn.=--Unfortunately in the canning process
of corn additions have been made to the product which are of an
objectionable nature. Chief among these is the use of bleaching agents
such as sulfur in the form of burnt sulfur or of sulfite or bisulfite
of soda or potash. These bleaching agents impart to the corn a white
color which some consumers prefer, but at the expense of introducing
a substance which must be regarded as deleterious to health. Still
more objectionable is the practice of using saccharin instead of sugar
as a sweetening agent. Saccharin is a coal tar product which has an
intense, sweet taste, very persistent, and when used alone becomes
disagreeable. A very small quantity of it is sufficient to impart
a very sweet taste to the canned corn at a much less expense than
could be secured by using the pure sugar. This form of adulteration
is extremely reprehensible both because it deceives the consumer and
adds a substance which by most hygienists is regarded as prejudicial
to health. The bleaching agent and the artificial sweetener are wholly
unnecessary. The manufacturers of sweet corn are expected to use the
best and freshest and sweetest materials and cannot be excused for
tampering with them in any way which either produces deception or
injury to health.
Sugar added to make an ordinary corn taste like sweet corn is to be
regarded as an adulteration unless its use is noted on the label.
Maize starch is also often added to sweet corn at the time of canning
and this practice can only be regarded as an adulteration.
=Detection of Adulterations in Sweet Corn.=--_Test for Sulfurous
Acid._--To about 25 grams of the sample (with the addition of water, if
necessary) placed in a 200-c.c. Erlenmeyer flask, add some pure zinc
and several cubic centimeters of hydrochloric acid. In the presence
of sulfites, hydrogen sulfid will be generated and may be tested
for with lead paper. Traces of metallic sulfids are occasionally
present in vegetables, and by the above test will indicate sulfites.
Hence positive results obtained by this method should be verified
by the distillation method.[24] It is always advisable to make the
quantitative determination of sulfites, owing to the danger that the
test may be due to traces of sulfids. A trace is not to be considered
sufficient as indicating either a bleaching agent or a preservative.
[24] U. S. Dept. Agr. Bureau of Chemistry, Circular No. 28, pp. 11-12.
_Detection of Saccharin._[25]--Add from 25 to 40 c.c. of water to about
20 grams of the sample; macerate and strain through muslin; acidify
with 2 c.c. of sulfuric acid (1 to 3) and extract with ether. Separate
the ether layer, allow the ether to evaporate spontaneously, and take
up the residue with water. If saccharin be present its presence will
be indicated by the sweet taste imparted to the water. To confirm this
test add from one to two grams of sodium hydroxid, and place the dish
in an oil bath. Maintain the temperature of the oil at 250° C. for 20
minutes, when the saccharin will be converted into salicylic acid.
After cooling and acidifying with sulfuric acid, extract in the usual
way and test for salicylic acid. This test, of course, presupposes the
absence of salicylic acid in the original sample. If salicylic acid is
present in the original sample it must be removed before making the
test for saccharin.
[25] _Ibid._, Bul. 65, p. 51.
[Illustration: FIG. 27.--INDIAN CORN STARCH. × 200.--(_Bureau of
Chemistry._)]
=Starch of Indian Corn.=--Maize starch has characteristics which enable
it to be easily detected by the microscope. The granules of this
starch are of a more uniform size than those of wheat and vary from
20 to 30 microns in diameter. Occasionally very much smaller granules
occur which probably are more of the original size and which have
been arrested in growth by the ripening of the grain. The granules of
maize starch are more or less polyhedral in form with round angles.
The only common cereal starch which they can be mistaken for is rice,
but they are generally larger than the granules of rice. Under the
microscope with ordinary light they give only the faintest sign of
rings but show in most cases a well developed hilum, which is at times
star-shaped or like an irregular cross, while at other times it has
the appearance of a circular depression. The maize starch granular is
a type of the angular, as the wheat is of the sphere or spheroid form.
The characteristic appearance of maize starch kernels is shown in the
accompanying Fig. 27. Viewed with polarized light the starch grains
of Indian corn present deep, well marked crosses, which divide each
grain into four distinct parts as shown in Fig. 28. It is interesting
to note that the angularity of maize starch is greatly influenced by
the hardness of the kernels from which the grains are taken. The hard
varieties, such as popcorn, have very angular grains while those from
soft varieties have a great many almost spherical forms.
[Illustration: FIG. 28.--STARCH GRAINS OF INDIAN CORN, UNDER POLARIZED
LIGHT. × 200.--(_Courtesy of Bureau of Chemistry._)]
=Maize Flour= (_Corn Meal_).--Formerly the maize kernel was ground
between stones, bolted to remove the bran, and the maize flour or
corn meal thus produced used directly as a human food. Modern milling
operations have changed the method of producing maize flour so that not
only is the outer bran removed but also, to a large extent, the germ
itself, thus diminishing the quantity of fat in the prepared meal. This
is notably true of the maize flour which is prepared for exportation.
Leaving in the flour such a large quantity of fat tends to produce
rancidity during shipment. To avoid any change of a deleterious nature
which the flour may undergo during shipment, it is also frequently
kiln-dried before being sent to foreign shores and even when intended
for domestic consumption at points remote from the mill.
While this preparation of maize flour is doubtless important for
transportation purposes, it impairs the palatability and nutritive
value of the product. It is advisable to continue to have the maize
flour prepared in the old-fashioned way and sent directly into
consumption.
=Method of Preparation.=--One method of preparing the maize flour is as
follows: The grains are broken into large pieces and dried with steam
heat at a temperature of from 105° to 110° C. (221°-239° F.). The mass
while still hot passes into a mill composed of two stones which revolve
rapidly in opposite directions. The smaller portions of the meal,
which have been reduced to a kind of gum by the high temperature, are
separated by this process from the covering or the bran of the kernel.
A small mass of the starchy matter leaves the mill in the form of small
noodles, which are freed from any particles of bran by sifting. In this
manner a mass is obtained which is quite free from fiber and fat.
The composition of maize meal prepared by the above process is as
follows:
Moisture, 9.70 percent
Protein, 12.68 „
Ether extract, 1.19 „
Ash, .60 „
Fiber, .35 „
Starch, sugar, and dextrin, 71.48 „
This method of preparing maize meal is not used to any extent in this
country, but is said to be commonly employed in Germany.
=Composition of Maize Flour.=--The color of maize flour depends upon
the color of the corn from which it is produced,--it may be white or
yellow. The starch granules when heated in water to 62.5° C. swell up
and become deformed, except a few, usually the small ones, which resist
the action of water at that temperature. The starch granules of maize
flour under polarized light present a black cross, very marked and very
distinct when the field is obscured. When viewed under polarized light
with a selenite plate the starch grains of maize are colored red with a
green cross or reciprocally, and this coloration is very brilliant.
As has already been said, the composition of Indian corn meal made by
the old-fashioned method of grinding and removing only the bran is
practically that of the whole grain itself.
The composition of degerminated maize meal (Indian corn flour) is shown
by the following average data:
Moisture, 12.57 percent
Protein, 7.13 „
Ether extract, 1.33 „
Ash, .61 „
Fiber, .87 „
Starch and sugar, 78.36 „
Calories calculated on the moist meal, 3,837
The above data show that the refined Indian corn meal has lost more
than three-fourths of its fat, a large portion of its mineral matter,
and also a very considerable proportion of its protein, due to the
separation of the bran which is extremely rich in protein and the germ
which is rich both in oil and protein. A mere glance at the data shows
that this refined Indian corn meal is much less nutritious than the
natural meal in so far as its content of tissue-forming bodies and its
faculty to furnish heat and energy are concerned. In other words, the
calories are very much lower than in the natural corn meal. This is
another reason for urging our people to return to the consumption of
the old-fashioned material.
=The Adulteration of Indian Corn Meal.=--Owing to the cheapness of
Indian corn in so far as is known there is no adulteration practiced.
The refined Indian corn flour itself is sometimes used as an
adulteration for buckwheat flour, wheat flour, and other cereal flours,
but has not itself been subjected to adulteration.
=Corn Bread= (_Indian Corn Bread_).--Corn bread is a very common diet
among all classes of people in the southern states and also to a
considerable extent in the north.
Owing to the lack of agglutinating powers of the nitrogenous
constituents of Indian corn flour, corn bread cannot be aerated or
raised, as is the case with wheat bread. It is often eaten in an
unleavened state. It may be partially leavened by the usual agent,
namely, yeast or a chemical baking powder. Two varieties of bread are
very commonly used, namely, that made of white flour or meal and that
made of yellow. There is apparently no difference in the nutritive
values of these two kinds. Some consumers prefer the white loaf and
some the yellow.
=Composition of Indian Corn Bread.=--The composition of bread depends
upon whether the whole grain flour is used from which only the coarse
bran has been removed by bolting or whether the decorticated and
degerminated meal is used. In the first case bread is made richer in
fat and protein and in the second case richer in starch. In the bread
will also be found the materials used in its preparation, namely,
salt, lard or other fats, milk, yeast, or baking powder residues. The
best bread is made from the freshly ground flour of the whole grain
from which only the outer covering, namely, the coarse bran has been
removed. As offered at many of our hotels and some private houses,
corn bread has been so manipulated as to lose a large part of its
palatability, without any compensating improvement of its nutritive
properties.
OATS (GENUS _Avena_).
This cereal is an important food product, being used very largely in
Europe, especially in Scotland, and also very extensively in this
country as human food. The chief use of oats is for cattle food,
especially for horses. It is extraordinarily rich in its nutritive
constituents and, therefore, is prized highly as a food in the building
and restoration of nitrogen tissues, such as the muscles. The variety
in common cultivation is _Avena sativa_ L.
Oats are grown in almost every part of the United States, but chiefly
in the northern and western portions. In the southern states the crop
is planted in the late autumn or early winter. In the northern states
it is chiefly a spring crop, being sown early in the spring as soon as
the ground is in fair condition. The oat crop is one which requires a
rather abundant and well-distributed rainfall. A spring drought is very
detrimental to the growth of oats, much more so than wheat or rye. It
is a crop which is well suited to be grown under irrigation.
There are many varieties of oats in cultivation, but in general
characteristics they all correspond to one description. The husk
adheres firmly to the grain, and when threshed the grain of a common
variety of oat carries the first layer of husk or chaff with it. Oats,
as bought in the market, therefore, consist not only of the kernel or
grain but also of this outer, chaffy envelope. The magnitude of the
crop in the United States is very great, but only an inconsiderable
proportion of the whole is used for human food, and this chiefly in
some form of oatmeal. The statistics of the crop grown in the United
States during 1906 are given in the following table:
Acreage, 30,958,768
Yield per acre, bushels, 31.2
Total yield, bushels, 964,904,522
Price per bushel, cents, 31.7
Total value at farm, $306,292,978
=Ratio of Kernel to Hull.=--Numerous examinations of unhulled oats show
that the average percentage of kernel to hull for 100 parts is as 73 to
27. In the oats grown in the western states the proportion of kernel is
relatively higher and in the southern states lower.
In the analytical process if the hull or chaff is ground with the
grain the proportion of fiber or crude cellulose is very considerably
higher than in the class of cereals ground without the chaff. The
mean composition of unhulled kernels of oats of American growth is
represented by the following table:
Weight of 100 unhulled grains, 2.92 grams
Moisture, 10.06 percent
Protein, 12.15 „
Ether extract, 4.33 „
Crude fiber, 12.07 „
Ash, 3.46 „
Starch and sugar, 57.93 „
A study of the above data shows that the flour of unhulled oats is rich
in fat, fiber, and ash. The large percentage of fiber and ash is due to
a great degree to the composition of the hulls or chaff. The fat or
oil comes chiefly from the germ.
=Composition of Hulled Oats.=--Inasmuch as the chaff is always
separated from the oat flour when the latter is to be used for human
food, the composition of the oat in the hulled state is of greater
importance to the present purpose than in the unhulled condition.
The means of 179 analyses show the hulled oats to have the following
compositions:
Moisture, 6.93 percent
Protein, 14.31 „
Ether extract, 8.14 „
Crude fiber, 1.38 „
Ash, 2.15 „
Starch and sugar, 67.09 „
The removal of the hulls, as is seen, and the partially dried condition
of the grain in the above analysis increases the percentage of other
ingredients. The protein and fat are especially large in quantity.
Oatmeals may be regarded as the richest of the cereal flours, both in
protein and in oil.
=The Protein of Oat Kernels.=--There are three principal products in
the oat kernels characterized by their different degrees of solubility,
namely, protein soluble in alcohol, protein soluble in dilute salt
solution, and protein soluble in alkali. The protein soluble in alcohol
constitutes about 1.25 percent of the whole grain, the protein soluble
in dilute salt solution about 1.5 percent, and the protein soluble in
alkali the remainder, viz., 11.25 percent. The protein of oats has very
little agglutinating power and, therefore, oat flour is not suitable
for making bread, or rather it is very little used for that purpose.
=Oat Products.=--As has been intimated before, the principal oat
products, as far as food is concerned, are the various forms of oatmeal
commonly classed as breakfast foods. These products are prepared in
various forms of agglutination and physical texture but if made from
genuine oats, as there is little cause for doubt, they have essentially
the same composition and nutritive power. It is doubtful if there is
any preparation of oatmeal any more nutritious or palatable than the
plain oat grain properly cooked. The forms in which the oat products
are offered to the public are perhaps more convenient for use and in
some cases by reason of heating and preparation require less trouble,
but otherwise they apparently have no advantage over the simple product.
The mean composition of a number of oat flour products is shown in the
following table:
Moisture, 7.66 percent
Protein, 15.48 „
Ether extract, 7.46 „
Crude fiber, 1.20 „
Ash, 1.29 „
Starch and sugar, 67.61 „
In the dry substance:
Protein, 16.77 percent
Ether extract, 8.08 „
Crude fiber, 1.38 „
Ash, 1.94 „
Starch and sugar, 73.20 „
Calories, 4,875
It is evident from the above average analysis that the products
examined are made from the whole kernel without the removal of the germ
but with a very careful removal of the hull and bran. The composition
of these products compares very favorably with the typical composition
of the kernel itself. These data show the high nutritive value of these
oat products, both in respect of fat and protein.
[Illustration: FIG. 29.--OAT STARCH. × 200.--(_Courtesy of Bureau of
Chemistry._)]
=Adulterations.=--There are very few adulterations of oatmeal.
Fortunately the price of this cereal is such that the admixture of
other cereals would not be profitable. Doubtless such admixtures have
often been made but evidently, from the examination of the products
upon the open market, they are not very frequent. The characteristic
appearance of oat starch is shown in Fig. 29.
Oat starch grains average about 10 microns in diameter. There are
usually present some grains of somewhat oval shape, which assist in
identifying oat products when present. The starch granules also have
a tendency to agglutinate into masses of varying size, as shown in the
photograph.
=Detection of Adulterations.=--The adulteration of oatmeal with the
flour of other cereals can easily be detected by the use of the
microscope. Oat starch when highly magnified presents a peculiar
cellular structure of pentagonal character which might be compared
to the effect produced by grinding a large number of faces upon a
precious stone. This peculiar appearance is caused by the tendency of
the starch granules in oats to become compacted in large masses. The
appearance of the separate granules and also the compact aggregate
are shown in the figure on the preceding page. The large aggregated
masses are of different sizes, ranging from .02 to 1.2 millimeters in
length. These masses are usually broken up by grinding or pressure and,
therefore, are not found in very great abundance in the commercial
oatmeal. When separated into single granules these are found to be
irregular in outline, due to the compression to which they have been
subjected, more or less pentagonal in structure, and from .015 to .02
millimeter in diameter. The starch granules do not show any very marked
characteristics under polarized light and have neither lines nor hilum.
The above statements can easily be verified by any one who can operate
an ordinary microscope, but before attempting to detect adulteration a
careful examination of starch granules, prepared by the investigator
himself, should be made.
RICE (_Oryza sativa_).
Rice is one of the most important food cereals. It furnishes a large
part of the food of the inhabitants of China and Japan. It is a food
rich in starch and poor in protein, and furnishes, therefore, heat and
energy, and is well adapted for the nourishment of those engaged in
hard labor or who undergo extreme physical exertion. The cultivation of
rice is rapidly extending in the United States, especially in Louisiana
and Texas. The statistical data relating to the rice crop for 1906 are
as follows:
Acreage, 575,014 acres
Production, 17,854,768 bushels
Yield per acre, 31.1 „
Price per bushel, 90.3 cents
Total value, 16,121,298 dollars
The adulteration of rice is confined to coating it with talc,
paraffin, and glucose. The object of this treatment is to give a
better appearance to the grain and to protect it from the ravages of
insects. The use of indigestible substances such as talc and paraffin
is scarcely justifiable. The starch granules of rice have distinctive
properties which enable them to be readily recognized under the
microscope, as shown in Fig. 30.
The rice starch grains are polygonal in form and have sharp angles.
The grains vary in size from 2 to 10 microns, though the latter size
is seldom reached, the most of the grains being about 6 microns. The
hilum is seldom visible. The grains occur in the rice kernels mostly in
groups of a considerable number of the individual grains forming starch
masses of ovoid or angular form.
[Illustration: FIG. 30.--RICE STARCH. × 200.--(_Courtesy of Bureau of
Chemistry._)]
RYE.
This is the source of the principal supply of bread in many European
countries, but is not extensively used in the United States except
among our citizens of foreign birth. It is also extensively used for
making whisky. Rye belongs to the genus _Secale_. Only one species
(_Secale cereale_ L.) is commonly cultivated, but this species has
a great many different varieties or races. According to the time of
sowing there are two great classes of rye, namely, that planted in the
autumn or early winter and that planted in the early spring, generally
known respectively as winter and spring rye. This is one of the
hardiest of cereals, and grows well in all locations where wheat and
other common cereals flourish. The area planted in rye in the United
States in 1906 and the quantity harvested are given in the following
table:
Acreage, 2,001,904
Yield per acre, 16.7 bushels
Production, 33,374,833 „
Price per bushel, 58.9 cents
Total value, 19,671,243 dollars
=Composition of Rye.=--From a study of many hundreds of analyses of rye
of American origin the following table may be given as approximating
the composition of a typical American rye:
Weight of 100 kernels, 2.50 grams
Moisture, 10.50 percent
Ether extract, 1.50 „
Protein, 12.25 „
Fiber, 2.10 „
Starch and sugar, 71.75 „
Ash, 1.90 „
[Illustration: FIG. 31.--RYE STARCH. × 200.--(_Courtesy of Bureau of
Chemistry._)]
The percentage of moisture in American grown rye is usually less than
that of European origin. The American rye, also, has smaller kernels
as a rule than that of foreign growth. In the content of protein the
American samples of rye are fully equivalent to those of foreign
origin, and in their mean composition, except as noted above, do not
differ greatly from that of standard varieties collected abroad.
=Protein of Rye.=--As is the case with other cereals more than one
nitrogenous constituent exists in the rye. Three of the principal
ones have been separated and named as follows: leucosin, gliadin,
and edestin. Other proteins belonging to the globulin, albumin, and
proteose family are also found in small proportions. The gliadin of
rye resembles in its chemical and physical properties the gliadin of
wheat. There is, however, in the rye no protein compound corresponding
to the glutenin of wheat, and, therefore, rye flour does not form a
gluten similar in quality to that of wheat, although it comes more
nearly doing so than any other cereal. The gliadin of rye is soluble in
alcohol, the leucosin of rye is soluble in water, and the edestin is
soluble in a salt solution.
In a typical sample of American rye there will be found about 5.16
percent of gliadin, 2.27 percent of edestin and proteose, 0.55 percent
of leucosin, and 3.14 percent of protein soluble in salt solution.
=Adulteration of Rye Flour.=--Rye flour is frequently adulterated
by the admixture of flours of other cereals. Real rye flour is
distinguished by the character of the starch granules, as shown in Fig.
31.
Rye starch grains are lenticular in form, and the largest grains are
of about 50 microns diameter. They average somewhat larger than wheat
starch grains and are characterized by many of the large grains having
a fissure in the form of a slit, cross, or star, which is rare in wheat
and barley. The rings and hilum are indistinctly seen in some of the
grains.
=Rye Bread.=--This bread may be made leavened or unleavened, since the
analogy in the property of its protein to that of wheat renders the
leavening of rye bread somewhat more easy of accomplishment than that
of the other cereals, with the exception of wheat.
Rye bread made of pure rye flour has a dark color, sometimes almost
black. It is often baked long in advance of the time of eating and
keeps well, is highly nutritious, and is the staple bread of many
European countries.
A partial rye flour bread is made by mixing rye flour with other
flours, such as wheat, barley, Indian corn, etc., and this is the kind
which is commonly used in this country and in many portions of Europe
where the light-colored breads are preferred to the dark.
The large consumption of bread made from rye and Indian corn indicates
that even if the supply of wheat should become limited there is no
reason to fear a famine of bread. It would be easy to substitute bread
made wholly or in part of Indian corn and rye for that made wholly of
wheat and thus to supply practically any demand for bread which the
increasing population of the earth may make.
WHEAT (GENUS _Triticum_).
In respect of human nutrition wheat is the most important of the
cereals. It is grown in the temperate regions of almost every country,
but does not flourish in tropical or subtropical countries.
In the United States the wheat is divided in respect of the period of
its growth into two great classes, namely, winter or fall planted wheat
and spring or spring planted wheat. Winter wheat is usually planted
from September to November and spring wheat from the last of March to
the last of April.
In this country wheat is not cultivated, that is, there is no
cultivation of the soil after seeding. The soil is, however, plowed and
harrowed before planting. In the winter wheat regions the harvesting
is in the month of June, though in the southern localities it comes
somewhat earlier and in the more northern localities may extend into
July. In the spring wheat regions the harvesting is from the last of
July to the middle or end of August. The statistics of wheat grown in
the United States during 1906 are as follows:
WINTER. SPRING.
Acreage, 29,599,961 17,705,868
Yield per acre (bushels), 16.7 13.7
Total yield (bushels), 492,888,004 242,372,966
Total value at farm, $336,435,081 $153,897,679
Price per bushel (cents), 68.3 63.5
All the different varieties of wheat which are now known are
cultivated. The simplest form, namely, the one grain wheat is the only
one which grows wild, and the origin of the other varieties of wheat is
unknown.
Botanists recognize three species, namely--Species 1, one grain wheat
(_Triticum monococcum_ Lam.); species 2, Polish wheat (_Triticum
polonicum_ L.); species 3, common wheat (_Triticum sativum_ Lam.). All
of these species are distinct, especially the third one, of which the
most valuable variety is the common wheat, _Triticum vulgare_ Vill.
The quality and properties of wheat depend more upon the environment
in which it is grown than upon the species to which it belongs. There
is perhaps no other field crop in which the environment, namely,
condition of the soil, temperature, precipitation, etc., makes a
greater difference than in wheat. In general, the environment and the
species together produce two kinds of wheat as far as milling and bread
making are concerned, namely, the soft or starchy wheat and the hard or
glutinous wheat. In the first variety there is a larger percentage of
starch in relation to the content or protein matter than in the second.
Taking the wheat as a whole its average composition is shown in the
following table:
Weight of 100 kernels, 3.85 grams
Moisture, 10.60 percent
Protein, 12.25 „
Ether extract, 1.75 „
Crude fiber, 2.40 „
Ash, 1.75 „
Carbohydrates other than crude fiber, 71.25 „
Dry gluten, 10.25 „
Moist gluten, 26.50 „
In regard to protein American wheat, as a rule, is quite equal to
that of foreign origin. This is an important characteristic when it
is remembered that both the milling and food value of a wheat depend
largely upon the nitrogenous matter which is present. It must not be
forgotten, however, that merely a good percentage of protein is not of
itself a sure indication of the milling value of a wheat. The ratio
of gluten to the other protein constituents in a wheat is not always
constant, but it is the gluten content of a flour on which the bread
making qualities chiefly depend.
=Gluten.=--The principal part of the protein in wheat is known as
gluten. Gluten as such does not exist in the wheat but is formed when
the pulverized wheat, that is, the wheat flour, is mixed with water
by the union of two elements in the wheat, namely, gliadin, which is
soluble in dilute alcohol and forms nearly half of the whole protein
matter of the wheat kernel, and glutenin, a compound insoluble in
water, dilute salt solutions, and dilute alcohol and which is quite as
abundant as gliadin in the wheat kernel. In fact, the gliadin and the
glutenin together make the whole of the protein, except a little over
one per cent.
There are three other forms of protein, as pointed out by Osborne,
in the wheat kernel, making altogether nearly 1¹⁄₂ percent of total
protein content. The average quantity of these compounds in the protein
of wheat is as follows.
Constituents:
Globulin, 0.70 percent
Albumin, 0.40 „
Proteose, 0.30 „
Gliadin, 4.25 „
Glutenin, 4.35 „
-----
10.00
=Starch in the Wheat Kernel.=--The most abundant constituent of the
wheat kernel is the starch. The appearance of wheat starch is shown in
the figure. Wheat starch grains ordinarily show the rings and hilum in
a few cases only under the most favorable conditions, though there are
sometimes cases where the striations are quite distinct. The granules
of starch vary greatly in size, being from 5 to 10 microns in diameter.
There are, in fact, two kinds of granules in wheat starch, one having
the appearance under the microscope of irregularly rounded particles
in sections like a circular disk, and the other of elongated particles
with a distinct hilum, as shown in Fig. 32. The appearance of the
granules under polarized light is shown in Fig. 33.
Wheat starch is not very commonly used for commercial purposes but is
highly prized for some things, especially in the sizing of textile
fabrics. The germ in wheat is particularly rich in oil and the bran or
outside covering in protein. The common idea that the bran is composed
mostly of silicious matter is wholly erroneous. On the contrary the
bran is a highly nutritious food, and the objection to it for human
food is mostly of a mechanical nature.
=Adulterations.=--Wheat grains are never adulterated but they may
sometimes contain dirt and foreign seeds, due to the growth of some
body in connection with the wheat itself.
=Standards.=--Wheat, commercially, is sold under three standards,
namely, one, two, three. The difference is an arbitrary one and not
founded upon any chemical data but wholly upon the physical appearance,
degree of moisture, and freedom from extraneous admixtures.
=Wheat Products.=--The principal product of wheat is flour. The
milling process for wheat is highly interesting both from a chemical
and technical point of view, but cannot be described in full in this
manual. The old-fashioned milling of wheat, namely, pressing between
stones and separation of the flour by bolting has been almost entirely
superseded by the modern milling with metal rollers.
[Illustration: FIG. 32.--WHEAT STARCH. × 200.--(_Courtesy of Bureau of
Chemistry._)]
Altogether nearly a hundred different products are made incident or
final to the milling of wheat. Only those products, however, which are
used for human food interest us at the present time.
=Chief Varieties of Flour.=--The highest grade of wheat flour is known
usually by the term “patent”; a lower grade is known as “bakers’ flour”
and a third as low grade flour. A barrel of flour weighs 196 pounds
and requires about 258 pounds of wheat for its manufacture. The whole
product from the 258.35 pounds of wheat is shown in the appended table.
In general it may be said that about 75 percent of the weight of the
wheat is obtained as merchantable flour of some kind, about 60 to 70
percent being good grade or straight flour. About 24 percent of the
weight of the wheat is obtained as cattle food and about 1 percent is
lost during the process of manufacture.
PRODUCT. POUNDS. PERCENTAGE.
Patent flour, 149.37 57.82
Bakers’ flour, 29.13 11.28
Low grade flour, 17.50 6.77
------ ------
Total flour, 196.00 75.87
Bran, 45.56 17.64
Shorts, 9.80 3.79
Screenings, 4.99 1.93
Waste, 2.00 0.77
------ ------
Total weight, 258.35 100.00
[Illustration: FIG. 33.--WHEAT STARCH UNDER POLARIZED LIGHT. ×
200.--(_Courtesy of Bureau of Chemistry_).]
=Special Names of Flour.=--In addition to the classification above
mentioned other names are used in many commercial senses for flour.
These additional names are “family,” “red dog,” “blended,” gluten, etc.
Many flours are also named after the name of the mill or locality or
bear simply fanciful names.
_Graham Flour._--This term was originally applied to the coarse,
unbolted flour which was made by grinding the whole wheat. The name,
therefore, should be applied to all flour made from well grained
wheat, ground, and unbolted. Most of the flours however, which are
sold nowadays as graham flours are produced by a more or less perfect
bolting process. From the above it is seen that true graham flour will
contain practically the same constituents as the wheat kernel itself
and in the same proportion and have the same composition as wheat.
_Entire Wheat Flour._--This name would naturally carry the idea of
a flour corresponding to the graham flour above mentioned. It is,
however, a misnamed trade-mark for a flour produced in a special manner
which consists in the removal of the outer or purely branny covering
of the grain. “Entire wheat” flour, therefore, contains all the
ingredients of wheat grains, save those which are found in the outer
branny covering.
_Gluten Flour._--This is a name applied to a flour which is produced
by removing the greater part of the starch from ordinary flour. It is
especially recommended for the use of diabetic patients. Unfortunately,
the name is very commonly applied to flours made from wheat containing
a little higher percentage of protein than the ordinary and sometimes
even to an ordinary wheat flour. Its use with such a product is purely
fraudulent.
_Mixed Flour._--The act of Congress of June 13, 1898, defines mixed
flour and imposes a tax upon the manufacture, sale, importation, and
exportation of that article. The maximum tax laid upon mixed flour is 4
cents on a barrel of 196 pounds. The total number of barrels of mixed
flour returned for taxation for the fiscal year ending June 30, 1905,
was 362; half barrels, 59,443; quarter barrels, 6,265; eighth barrels,
24,974. The total quantity of mixed flour returned for taxation during
the year is 5,495,937 pounds. The above data show that the amount of
mixed flour offered for sale is a very small part of the total flour
manufactured in the United States. It may be that there is a great
deal of flour mixed and sold in violation of the law since it is
quite impossible in the inspection of the stores to supervise all the
transactions of business deals in flour; especially is it believed that
rye flour and buckwheat flour are often adulterated by mixing with
them the flour of other cereals. This adulteration is not one which is
at all injurious to health but is simply practiced for the purpose of
making a rye or buckwheat flour look whiter or because the added flours
are cheaper than the real rye or buckwheat.
=Properties Affecting the Commercial Value of Flour.=--Aside from its
nutritive properties wheat flour has a commercial value depending
upon its color and texture and upon the gluten which it contains. The
character of gluten also varies largely in different varieties of wheat
and in wheat grown in different localities. A chemical examination
will not always tell the bread making properties of a flour, and the
character of the bread itself depends often quite as much upon the
skill of the baker as upon the flour which is used.
In cases where loaves are sold by weight, a flour with a high
percentage of tenacious gluten is often preferred, since it permits of
the forming of loaves containing a maximum percentage of water. With a
flour rich in gluten it is not difficult to make a palatable loaf which
does not bear any evidence of an excess of water, containing as much
as 40 percent of moisture. The baking of bread is an art which is most
successfully practiced by professionals, and the American method of
home bread making does not always lead to the happiest results.
The ideal flour for bread making is one which contains a sufficient
quantity of gluten to make a porous and spongy loaf, but not one which
permits an excessive quantity of moisture to be incorporated in the
loaf itself.
=Average Composition of Different Varieties of Flour.=--Analyses of a
great number of samples of different varieties of flours lead to the
following data, which may be accepted as a very close approximation
of the average variety of different grades of flour offered upon the
American market:
-------------------------+--------+--------+--------+--------+
| | PRO- | PRO- | |
| | TEIDS | TEIDS | |
| MOIS- | N × | N × | MOIST |
NAME OF FLOUR. | TURE. | 6.25. | 5.70. | GLUTEN.|
-------------------------+--------+--------+--------+--------+
|_Perct._|_Perct._|_Perct._|_Perct._|
Patent flour, | 12.77 | 10.55 | 9.62 | 25.97 |
Bakers’ and family flour,| 11.69 | 12.28 | 11.20 | 34.70 |
Common market flour, | 12.28 | 10.18 | 9.28 | 24.55 |
Miscellaneous flour, | 12.73 | 10.45 | 9.52 | 26.80 |
Self-raising flour, | 11.45 | 9.75 | 8.89 | 26.97 |
Gluten flour, | 12.99 | 13.30 | 12.13 | 39.68 |
-------------------------+--------+--------+--------+--------+
-------------------------+--------+--------+--------+--------+
| | | | STARCH |
| | | | N × |
| DRY | | | 6.25. |
NAME OF FLOUR. | GLUTEN.| OIL. | ASH. | [26] |
-------------------------+--------+--------+--------+--------+
|_Perct._|_Perct._|_Perct._|_Perct._|
Patent flour, | 9.99 | 1.02 | 0.44 | 74.76 |
Bakers’ and family flour,| 13.07 | 1.30 | 0.57 | 73.87 |
Common market flour, | 9.21 | 1.30 | 0.61 | 75.63 |
Miscellaneous flour, | 10.22 | 1.08 | 0.49 | 75.23 |
Self-raising flour, | 9.65 | 0.70 | 4.45 | 73.66 |
Gluten flour, | 14.84 | 1.05 | 0.55 | 72.11 |
-------------------------+--------+--------+--------+--------+
-------------------------+--------+--------+-------
| STARCH | |
| N × | |
| 5.70. | CRUDE | CALO-
NAME OF FLOUR. | [26] | FIBER. | RIES.
-------------------------+--------+--------+-------
|_Perct._|_Perct._|
Patent flour, | 76.14 | 0.21 |3,858.0
Bakers’ and family flour,| 74.98 | 0.22 |3,929.6
Common market flour, | 76.53 | 0.28 |3,882.5
Miscellaneous flour, | 76.15 | 0.25 |3,846.3
Self-raising flour, | 74.51 | 0.21 |3,719.3
Gluten flour, | 73.28 | 0.32 |3,891.1
-------------------------+--------+--------+-------
[26] In the first of these columns the starch is calculated by
difference, assuming the protein to be the quantity of nitrogen
present multiplied by 6.25, and in the second column the figure is
obtained in the same way, using 5.70 as the protein factor.