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 | „ |
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.
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 |
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:
| Name of Flour. | Mois- ture. | Pro- teids N × 6.25. | Pro- teids N × 5.70. | Moist Gluten. | Dry Gluten. | Oil. | Ash. | Starch N × 6.25. [26] | Starch N × 5.70. [26] | Crude Fiber. | Calo- ries. |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Perct. | Perct. | Perct. | Perct. | Perct. | Perct. | Perct. | Perct. | Perct. | Perct. | ||
| Patent flour, | 12.77 | 10.55 | 9.62 | 25.97 | 9.99 | 1.02 | 0.44 | 74.76 | 76.14 | 0.21 | 3,858.0 |
| Bakers’ and family flour, | 11.69 | 12.28 | 11.20 | 34.70 | 13.07 | 1.30 | 0.57 | 73.87 | 74.98 | 0.22 | 3,929.6 |
| Common market flour, | 12.28 | 10.18 | 9.28 | 24.55 | 9.21 | 1.30 | 0.61 | 75.63 | 76.53 | 0.28 | 3,882.5 |
| Miscellaneous flour, | 12.73 | 10.45 | 9.52 | 26.80 | 10.22 | 1.08 | 0.49 | 75.23 | 76.15 | 0.25 | 3,846.3 |
| Self-raising flour, | 11.45 | 9.75 | 8.89 | 26.97 | 9.65 | 0.70 | 4.45 | 73.66 | 74.51 | 0.21 | 3,719.3 |
| Gluten flour, | 12.99 | 13.30 | 12.13 | 39.68 | 14.84 | 1.05 | 0.55 | 72.11 | 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.
Separation of Gluten.
—The character of a wheat flour, as has already been intimated, is measured largely by the quantity of gluten which it may contain. The separation of gluten may be accomplished by any one, even without a chemical training, by a little practice. It is, therefore, one of the tests for the value of a wheat flour which can be easily and generally applied. The principle of separation of the gluten rests upon the fact that when wheat flour is moistened and kneaded into a sticky mass it may be washed with pure water with constant kneading until nearly all the starch has been removed from the mass. Meanwhile only that portion of the protein is removed which is soluble in the water and the gluten which is formed by the process of kneading remains as a sticky mass. When this moist mass is kneaded and rolled until all the moisture is taken out of it that can be removed in this way, it may be weighed and the proportion of moist gluten in the sample determined. It may then be placed in an oven and dried, and then the proportion of dry gluten secured. The following method is one which is easily applied. Place 10 grams of the sample in a porcelain dish and moisten with from 6 to 7 cubic centimeters of water, knead, and allow to stand for an hour. Work into a ball, being careful that none of the material adheres to the dish. Holding the mass in the hand knead it in a slow stream of cold water until the starch and all soluble matter are washed out. Place the ball of gluten thus formed in cold water and allow to stand for one hour; remove from water, press as dry as possible between the hands, roll into a ball, and weigh in a flat-bottomed dish. After weighing, place the ball of moist gluten in the drying oven for twenty hours; cool and weigh.
Fig. 34.—Kedzie’s Farinometer Showing the Parts.—(Bulletin 13, U. S. Dept. of Agriculture.)
Gluten Tester.
—A simple test for determining the approximate percentage of gluten in flour may be used, based upon the principle that the viscosity of dough is a measure of its practical gluten content. The name applied to a gluten tester is farinometer.
A convenient form of farinometer devised by Kedzie is shown in the accompanying figure. It is patterned somewhat upon the plan of Jago’s viscometer. The instrument is shown in parts in [Fig. 34]. The instrument as in use is exhibited in [Fig. 35]. Parts shown in [Fig. 34] are as follows: No. 1 is the stand or support of the parts. No. 2 is the cap of No. 1, and discloses the half-inch opening (half closed by the slide) through which the dough is forced by the pressure of the rod No. 4. The slide by which this opening is closed is plainly shown; also the socket for holding No. 3. No. 3 is a brass tube 3 inches high and 1 inch internal diameter, with a small knob to fit into the notched opening in the side of the socket seen in No. 2, to hold No. 3 firmly in place. No. 4 is a steel rod 15⁄16 inch in diameter and 12 inches long, with a thin brass cap 1 inch in diameter, beveled slightly so that the front edge fills the barrel of No. 3 without friction, and is yet dough-tight. Near the top the rod is marked into inch spaces.
In using the farinometer two points are considered:
1. The water-absorbing power of a flour, or the percentage of water it will take up to form a dough of a certain consistency.
2. The viscosity of such dough, or its resistance to change of form under a uniform force; e. g., the length of time in seconds required to force a cylinder of dough 1 inch high through a hole one-half inch in diameter under the pressure of a vertical steel rod 13 inches long and weighing 21⁄2 pounds avoirdupois.
Fig. 35.—Kedzie’s Farinometer in Use.—(Bulletin 13, U. S. Dept. of Agriculture.)
Bleaching of Flour.
—At the present time flour is extensively bleached for the purpose of making an inferior article resemble a superior one. By this means a greater percentage of the flour produced can be rated as of first quality. Ozone and oxids of nitrogen developed by electrical discharges are the principal bleaching agents employed. Bleached flour should bear a label indicating to the purchaser the character of the manipulation to which it has been subjected.
Adulterations of Flour.
—The adulteration of wheat flour is not practiced to any extent in this country. The most common adulteration arises from grinding with wheat foreign seeds and other foreign matter, rust, smut, etc., which may be present in the grain. Other adulterations are the mixture with wheat flour of the starch or flour of maize and other cereals. The adulteration with any form of terra alba or white powdered earthy substance is exceedingly rare. Although some attempts have been made to introduce such adulterations in this country they have not reached any commercial success. The adulterations, with the exception of those with white earthy powders, are most readily ascertained by microscopic examination for foreign matters and other varieties of starch than grow naturally in the wheat.
Standard.
—The United States standard for flour is as follows:
Flour is the fine, sound product made by bolting wheat meal and contains not more than thirteen and one-half (13.5) percent of moisture, not less than one and twenty-five hundredths (1.25) percent of nitrogen, not more than one (1.0) percent of ash, and not more than fifty hundredths (0.50) percent of fiber.
Graham flour is unbolted wheat meal.
Whole wheat flour, entire wheat flour, improperly so called, is fine wheat meal from which a part of the bran has been removed.
Gluten flour is the product made from flour by the removal of starch, and contains not less than five and six-tenths (5.6) percent of nitrogen and not more than ten (10) percent of moisture.
Age of Flour.
—The freshly ground flour is most highly esteemed by many consumers on account of palatability and freedom from all danger of mold and ferments. Older flours are likely to lose flavor, become moldy and infested with weavil and other insect pests. The last-named evils are avoided by the use of wheat containing no fungus, none of the eggs of the weavil, nor of other insects, and enclosing the freshly ground flour in packages not accessible to infection. Even then it is advisable to consume the flour as soon as convenient after the milling process. Many manufacturers and experts contend that flour is improved by keeping for a certain length of time, and this contention is based on the assumption that the flour assumes a lighter color and improves in flavor on keeping. There is of course a certain limit to improvements of this kind.
Substitutes for Flour.
—Wholesome ingredients are used in part instead of flour in bread making, and when that fact is clearly made known the admixture of these substances with flour is not considered an adulteration. Bread which is made of an admixture of Indian corn meal with flour or rye flour with flour or other cereal products is well liked by many people. Potatoes are also used very often in bread making. Acorns, buckwheat, and other farinacious and oily substances are also employed. The admixture of inert substances with flour merely to increase the bulk and weight of the loaf, even if notified, cannot be regarded as other than an adulteration.
In times of famine such admixtures are sometimes made in order to increase the size and weight of the loaf. Such substances are known in times of famine as “hunger bread.” Finely ground straw, bark, the hulls of nuts, etc., are often used for this purpose. These bodies practically have no nutritive value and serve no useful purpose except to deceive the eater respecting the quantity of bread he consumes.