Scientific American Supplement, No. 275, April 9, 1881. Various
offers a particular interest; the center, No. 9, is the softest part; it contains the least gluten and the most starch; it is the part which first pulverizes under the stone, and gives, after the first bolting, the fine flour. As this flour is poorest in gluten, it makes a dough with little consistency, and incapable of making an open bread, well raised. The first layer, No. 8, which surrounds the center, produces small white middlings, harder and richer in gluten than the center; it bakes very well, and weighs 20 lb. in 100, and it is these 20 parts in 100 which, when mixed with the 50 parts in the center, form the finest quality flour, used for making white bread.
The layer No. 7, which surrounds the preceding one, is still harder and richer in gluten; unfortunately in the reduction it becomes mixed with some hundredth parts of the bran, which render it unsuitable for making bread of the finest quality; it produces in the regrinding lower grade and dark flours, together weighing 7 per cent. The external layer, naturally adhering to the membrane, No. 6, becomes mixed in the grinding with bran, to the extent of about 20 per cent., which renders it unsuitable even for making brown bread; it serves to form the regrindings and the offals destined for the nourishment of animals; this layer is, however, the hardest, and contains the largest quantity of gluten, and it is by consequence the most nutritive. We now see the endosperm increasing from the center, formed of floury layers, which augment in richness in gluten, in proportion as they are removed from the center. Now, as the flours make more bread in proportion to the quantity of gluten they contain, and the gluten gives more bread in proportion to its being more developed, or having more consistence, it follows that the flour belonging to the parts of the berry nearest the envelopes or coverings should produce the greatest portion of bread, and this is what takes place in effect. The product of the different layers of the endosperm is given below, and it will be seen that the quantity of bread increases in a proportion relatively greater than that of the gluten, which proves once more that the gluten of the center or last formation has less consistence than that of the other layers of older formation.
The following are the results obtained from the same wheat:
On the whole, it is seen, according to the composition of the floury part of the grain, that the berry contains on an average 90 parts in 100 of flour fit for making bread of the first quality, and that the inevitable mixing in of a small quantity of bran reduces these 90 to 70 parts with the ordinary processes; but the loss is not alone there, for the foregoing table shows that the best portion of the grain is rejected from the food of man that brown or dark bread is made of flour of very good quality, and that the first quality bread is made from the portion of the endosperm containing the gluten in the smallest quantity and in the least developed form.
This is a consideration not to be passed over lightly; assuredly the gluten of the center contains as much azote as the gluten of the circumference, but it must not be admitted in a general way that the alimentary power of a body is in connection with the amount of azote it contains, and without entering into considerations which would carry us too wide of the subject, we shall simply state that if the flesh of young animals, as, for instance, the calf, has a debilitating action, while the developed flesh of full-grown animals–of a heifer, for example–has really nourishing properties, although the flesh of each animal contains the same quantity of azote, we must conclude that the proportion of elements is not everything, and that the azotic or nitrogenous elements are more nourishing in proportion as they are more developed. This is why the gluten of the layers nearest the bran is of quite a special interest from the point of view of alimentation and in the preparation of bread.
THE EMBRYO AND THE COATING OF THE EMBRYO
To be intelligible, I must commence by some very brief remarks on the tissues of vegetables. There are two sorts distinguished among plants; some seem of no importance in the phenomena of nutrition; others, on the contrary, tend to the assimilation of the organic or inorganic components which should nourish and develop all the parts of the plant. The latter have a striking analogy with ferments; their composition is almost similar, and their action is increased or diminished by the same causes.
These tissues, formed in a state of repose in vegetables as in grain, have special properties; thus the berry possesses a pericarp whose tissues should remain foreign to the phenomena of germination, and these tissues show no particularity worthy of remark, but the coating of the embryo, which should play an active part, possesses, on the contrary, properties that may be compared to those of ferments. With regard to these ferments, I must further remark that I have not been able, nor am I yet able, to express in formula my opinion of the nature of these bodies, but little known as yet; I have only made use of the language mostly employed, without wishing to touch on questions raised by the effects of the presence, and by the more complex effects of living bodies, which exercise analogous actions.
With these reservations I shall proceed to examine the tissues in the berry which help toward the germination.
THE EMBRYO (10, see woodcut) is composed of the root of the plant, with which we have nothing to do here. This root of the plant which is to grow is embedded in a mass of cells full of fatty bodies. These bodies present this remarkable particularity, that they contain among their elements sulphur and phosphorus. When you dehydrate by alcohol 100 grammes of the embryo of wheat, obtained by the same means as the membrane (a process indicated later on), this embryo, treated with ether, produces 20 grammes of oils composed elementarily of hydrogen, oxygen, carbon, azote, sulphur, and phosphorus. This analysis, made according to the means indicated by M. Fremy, shows that the fatty bodies of the embryo are composed like those of the germ of an egg, like those of the brain and of the nervous system of animals. It is necessary for us to stop an instant at this fact: in the first place, because it proves that vegetables are designed to form the phosphoric as well as the nitrogenous and ternary aliments, and finally, because it indicates how important it is to mix the embryo and its dependents with the bread in the most complete manner possible, seeing that a large portion of these phosphoric bodies always become decomposed during the baking.
COATING OF THE EMBRYO.–This membrane (6), which is only an expansion of the embryo, surrounds the endosperm; it is composed of beautiful irregular cubic cells, diminishing according as they come nearer to the embryo. These cells are composed, first, of the insoluble cellular tissue; second, of phosphate of chalk and fatty phosphoric bodies; third, of soluble cerealine. In order to study the composition and the nature of this tissue, it must be completely isolated, and this result is obtained in the following manner.
The wheat should be damped with water containing 10 parts in 100 of alcoholized caustic soda; at the expiration of one hour the envelopes of the pericarp, and of the testa Nos. 2, 3, 4, 5, should be separated by friction in a coarse cloth, having been reduced by the action of the alkali to a pulpy state; each berry should then be opened separately to remove the portion of the envelope held in the fold of the crease, and then all the berries divided in two are put into three parts of water charged with one-hundredth of caustic potash. This liquid dissolves the gluten, divides the starch, and at the expiration of twenty-four hours the parts of the berries are kneaded between the fingers, collected in pure water, and washed until the water issues clear; these membranes with their embryos, which are often detached by this operation, are cast into water acidulated with one-hundredth of hydrochloric acid, and at the end of several hours they should be completely washed. The product obtained consists of beautiful white membranes, insoluble in alkalies and diluted acids, which show under the microscope beautiful cells joined in a tissue following the embryo, with which it has indeed a striking analogy in its properties and composition. This membrane, exhausted by the alcohol and ether, gives, by an elementary analysis, hydrogen, oxygen, carbon, and azote. Unfortunately, under the action of the tests this membrane has been killed, and it no longer possesses the special properties of active tissues. Among these properties three may be especially mentioned:
1st. Its resistance to water charged with a mineral salt, such as sea salt for instance
2d. Its action through its presence.
3d. Its action as a ferment.
The action of saltwater is explained as follows: When the berry is plunged into pure water it will be observed that the water penetrates in the course of a few hours to the very center of the endosperm, but if water charged or saturated