The Commercial Products of the Vegetable Kingdom Part 32

I have heretofore adverted to the great care employed in the drying of grain in various foreign countries, and to which the preservation of it for a great number of years is to be ascribed.

The operation is not conducted in the hurried manner which is here thought to be so essential, but is continued long enough to effect the intended object. Thorough ventilation, as well as the proper degree of drying, and which is equally important, is thus secured.

It is said that in Russia the sheaves of wheat, carried into the huts, are suspended upon poles and dried by the heat of the oven.

The grain shrinks very much during this process, but it is supposed to be less liable to the attacks of insects, and preserves its nutritive qualities for many years. During the winter, it is sent to market.--("The Czar, his Court and People." By John S. Maxwell, p.

272.)

With all the necessary attention which may be paid to the proper drying of our breadstuffs intended for export, another point is of equal importance, viz., the s.h.i.+pment in vessels rendered as impervious as possible to the influence of atmospheric moisture. For however carefully and thoroughly the drying, especially of wheat flour or maize meal, may have been performed, it will be nearly useless if the s.h.i.+pment is afterwards made in the barrels commonly employed.[29] And it is very certain that the transport and s.h.i.+pment of grain in bulk, as usually conducted, are attended with great loss. This difficulty might be removed at a trifling expense by adopting the plan suggested in the preceding report, and to which I would again respectfully call the attention of those who are engaged in this branch of trade.

I might here adduce a ma.s.s of testimony showing the importance of the matters just referred to, but will only advert to the following statements, which although made in allusion princ.i.p.ally to maize, are equally applicable to our other breadstuffs. Maize meal, if kept too long, "is liable to become rancid, and it is then more or less unfit for use. In the s.h.i.+pments made to the West Indies, the meal is commonly kiln-dried, to obviate as much as possible this tendency to rancidity." "When ground very fine, maize meal suffers a change by exposure to the air. It is oxygenated. It is upon the same principle that the juice of an apple, after a little exposure to the air, is oxygenated, and changes its character and taste. If the flour could be bolted _in vacuo_, it would not be changed." "Intelligent writers speak of the necessity of preparing corn for exportation by kiln-drying as indispensable. Without that process, corn is very liable to become heated and musty, so as to be unfit for food for either man or beast. The kiln-dried maize meal from the Brandywine Mills, &c., made from the yellow corn, has almost monopolized the West India trade. This process is indispensable, if we export maize to Europe. James Candy says that from fifty years experience he has learned the necessity of this process with corn intended for exportation." "I have often found the corn from our country when it reached its destination, ruined by heating on the voyage. It had become musty and of little or no value. Kiln-drying is absolutely necessary to preserve it for exportation. We must learn and practice the best mode of kiln-drying it.[30]"

_The nutritious value of the "whole meal" of Wheat, as compared with that of the fine flour_.--The question whether what is called the whole meal of wheat, or that which is obtained by the mixture of the bran, contains more nutritious matter than the fine flour, is one of great importance. In my former report, I adverted to the statement made in regard to it by Professor J.F.W. Johnston, and which seemed to be almost conclusive in favor of the value of the whole meal. During the past year, however (1849), M. Eug. Peligot, an eminent French chemist, in an elaborate article "On the Composition of Wheat," to which more particular reference will be made hereafter, combats the opinion that the bran is an alimentary substance. He observes that "the difficulty of keeping the bran in flour intended for the manufacture of bread of good quality appears to result much less from the presence of the cellulose (one of the const.i.tuents of woody matter) contained in wheat than that of the fatty matter.

This is found in the bran in a quant.i.ty at least triple of that which remains in the flour, and the bolting separates it from the ground wheat not less usefully than the cellulose itself."[31] M.

Millon objects entirely to the views of M. Peligot on this point, and states some facts which are especially worthy of consideration. He a.s.serts that, according to the views of the last named chemist, the separation at most of one part of fatty matter sacrifices fifteen, twenty, and even twenty-five per cent.

of substances which are of the highest nutritive value. This abstracts from wheat, for the whole amount raised in France, the enormous sum of about two hundred millions of pounds annually.

It seems that in France the question whether the bolting of flour is advantageous has always been decided in the most arbitrary manner.

An ordinance of Louis XIV., issued in 1658, prohibited, under a very heavy penalty, the regrinding of the bran and its mixture with the flour; this, with the mode of grinding then in use, caused a loss of more than forty per cent.--(Comptes Rendus, February 19th, 1849.)

In large cities and elsewhere, there seems for some time to have been a growing prejudice against the use of brown bread; and it is said that now nearly all the peasantry of France bolt their flour.

The increase of this practice, according to M. Millon, threatens the nation with an annual loss of from two to three hundred millions of francs. If the bran was entirely valueless, there would be a loss of more than one million a day.

It is quite difficult to determine the precise amount of bran which may have been removed from wheat, for various samples contain such a different proportion of bran that in the one case a removal of ten per cent, leaves more bran in the flour than a bolting of five per cent. in another.

The following is an a.n.a.lysis of bran by M. Millon; the sample being a soft French wheat grown in 1848:--

Starch, dextrine and sugar 53.00 Sugar of liquorice 1.00 Gluten 14.90 Fatty matter 3.60 Woody matter 9.70 Salts .50 Water 13.90 Incrusting matter and aromatic principles (by difference) 3.40 ------ 100.

The conclusion to be drawn from this a.n.a.lysis is, that bran is an alimentary substance. If it contains six per cent. more of woody matter than the rough, flour, it has also more gluten, double that of fatty matter, besides two aromatic principles which have the perfume of honey, and both of which are wanting in the fine flour.

Thus by bolting, wheat is impoverished in its most valuable principles, merely to remove a few hundredths of woody matter.

The economical suggestion which springs from these views is, that the bran and coa.r.s.e flour should be reground and then mixed with the fine flour. Millon states that he has ascertained, by repeated experiments, that bread thus made is of superior quality, easily worked, and not subject to the inconvenience of bread manufactured from the rough flour, such as is made in some places, and especially in Belgium.

Opinions similar to those above noticed are entertained by Professor Daubeny. "The great importance attached to having bread perfectly white is a prejudice," he says, "which leads to the rejection of a very wholesome part of the food, and one which, although not digestible alone, is sufficiently so in that state of admixture with the flour in which nature has prepared it for our use." After quoting the remarks of Professor Johnston on the same side of the question, he adds, "that according to the experiments of Magendie, animals fed upon fine flour died in a few weeks, whilst they thrived upon the whole meal bread." Brown bread, therefore, should be adopted, not merely on a principle of economy, but also as providing more of those ingredients which are perhaps deficient in the finer parts of the flour.--("Gardeners' Chronicle," January 27th, 1849, p.

53.)

The remarks of Dr. Robertson may also be here introduced. "The advantage," he observes, "of using more or less of the coverings of the grain in the preparation of bread has often been urged on economical principles. There can be no doubt that a very large proportion of nutritive matter is contained in the bran and the pollard; and these are estimated to contain about one-fifth part of the entire weight of the wheat grain. It is, unquestionably, so far wasteful to remove these altogether from the flour; and in the case of the majority of people, this waste may be unnecessary, even on the score of digestibility."[32] This subject can also be rendered apparent to the eye. If we make a cross section of a grain of wheat, or rye, and place it under the microscope, we perceive very distinct layers in it as we examine from without inwards. The outer of them belong to the husk of the fruit and seed, and are separated as bran, in grinding. But the millstone does not separate so exactly as the eye may by means of the microscope, not even as accurately as the knife of the vegetable anatomist, and thus with the bran is removed also the whole outer layer of the cells of the nucleus, and even some of the subjacent layers. Thus the anatomical investigations of one of these corn grains at once explains why bread is so much the less nutritious the more carefully the bran has been separated from the meal.[33] There can therefore be little doubt that the removal of the bran is a serious injury to the flour; and I have presented the above array of evidence on this point in the hope of directing public attention to it here, as has been done in various foreign countries.

After this, it will easily be inferred that I am not disposed to look with much favor upon the plan proposed by Mr. Bentz for taking the outer coating or bran from wheat and other grains previously to grinding.[34] Independently of the considerations which have already been presented, it is far from being proved, as this gentlemen a.s.serts, that the mixture of the bran with the meal which results from the common mode of grinding is the chief cause of the _souring_ of the flour in hot climates. On the contrary, the bran is perhaps as little liable to undergo change as the fine flour, and then the moistening to which, as I am informed, the grain is subjected previously to the removal of the husk, is still further objectionable, and must be followed by a most carefully-conducted process of kiln-drying.

_Nutritious properties of various articles of food_.--There seems to be some difference of opinion in regard to the nutritious properties of various kinds of food. It is generally, however, agreed that those which contain the largest proportion of nitrogenous matters are the most nutritious. It is on this account that haricots, peas, and beans, form, in some sort, subst.i.tutes for animal food. Tubers, roots, and even the seeds of the cereal gra.s.ses, are but moderately nutritious. If we see herbivorous animals fattening upon such articles, it is because, from their peculiar organisation, they can consume them in large quant.i.ties. It is quite doubtful whether a man doing hard work could exist on bread exclusively. The instances which are given of countries where rice and potatoes form the sole articles of food of the inhabitants, are believed to be incomplete.

Boussingault states that in Alsace, for example, the peasantry always a.s.sociate their potato dish with a large quant.i.ty of sour or curdled milk; in Ireland with b.u.t.termilk. "The Indians of the Upper Andes do not by any means live on potatoes alone, as some travellers have said they do: at Quito, the daily food of the inhabitants is _lorco_, a compound of potatoes and a large quant.i.ty of cheese. Rice is often cited as one of the most nouris.h.i.+ng articles of diet. I am satisfied, however, after having lived in countries where rice is largely consumed, that it is anything but a substantial, or, for its bulk, nutritious article of sustenance."--("Rural Economy," Amer.

edition, p. 409.) These statements are further confirmed by the observations of M. Lequerri, who, during a long residence in India, paid particular attention to the manners and customs of the inhabitants of Pondicherry. "Their food," he states, "is almost entirely vegetable, and rice is the staple; the inferior castes only ever eat meat. But all eat _kari_ (curry), an article prepared with meat, fish, or vegetable, which is mixed with the rice, boiled in very little water. It is requisite to have seen the Indians at their meals to have any idea of the enormous quant.i.ty of rice which they will put into their stomachs. No European could cram so much at a time; and they very commonly allow that rice alone will not nourish them. They very generally still eat a quant.i.ty of bread."[35] In regard to the proportion of nutritious matter contained in grains of various kinds, it may be remarked that the tables which have been constructed as the results of various experiments are liable to an objection, which will be more particularly adverted to under another head. For example, two substances, by the process of ultimate a.n.a.lysis, may exhibit the same proportion of nitrogenous matter, and still differ very materially in their value as articles of food.

Much depends on the digestibility of the form in which this matter is presented to the digestive organs. A strong ill.u.s.tration is afforded in the case of hay, the proportion of nutritive matter of which, about 9.71, would certainly not represent its power of affording nourishment to the human system. It is in truth quite impossible to arrive at any other than approximate results from the operations of chemistry, as to the amount of nutriment contained in a given quant.i.ty or weight of any article of food.[36] It is perhaps not irrelevant to notice in this place some of the researches which have recently been made upon fermentation, and particularly its effects in the manufacture of bread. It appears that when this process is brought about by the addition of yeast or leaven to the paste or dough, the character of the ma.s.s is materially altered. A larger or smaller proportion of the flour is virtually lost.

According to Dr. William Gregory the loss amounts to the very large proportion of one-sixteenth part of the whole of the flour. He says, "To avoid this loss, bread is now raised by means of carbonate of soda, or ammonia and a diluted acid, which are added to the dough, and the effect is perfectly satisfactory. Equally good or better bread is obtained, and the quant.i.ty of flour which will yield fifteen hundred loaves by fermentation, furnishes sixteen hundred by the new method, the sugar and fibrin (gluten) being saved."--("Outlines of Chemistry," p. 352.)

Another author, Dr. R.D. Thomson, states, as the results of his experiments upon bread produced by the action of hydrochloric acid upon carbonate of soda, "that in a sack of flour there was a difference in favor of the unfermented bread to the amount of thirty pounds thirteen ounces, or in round numbers, a sack of flour would produce one hundred and seven loaves of unfermented bread, and only one hundred loaves of fermented bread of the game weight. Hence it appears that in the sack of flour by the common process of baking, seven loaves, or six-and-a-half per cent, of the flour are driven into the air and lost."--("Experimental Researches on the Food of Animals," &c., p. 183.)

The only objection to the general introduction of this process seems to be the degree of care and accuracy required in properly adjusting the respective qualities and quant.i.ties of acid and alkali, and which could seldom be attained even by those who are largely engaged in the manufacture of bread.

I cannot leave this subject without adverting to a practice which has prevailed in England and France, and perhaps also in this country, of steeping wheat before sowing it in solutions of a.r.s.enic, sulphate of copper, and other poisonous preparations.

The result has been that injurious effects have often followed, both to those who are employed in sowing such grain, and to those who have used the bread manufactured from it. The great importance of the subject led to the appointment of a commission at Rouen, in France, in December, 1842, having for its object to determine the best process of preventing the s.m.u.t in wheat, and to ascertain whether other means less dangerous than those above noticed were productive of equally good results. The labors of this commission extended over the years 1843-'44-'45, and the experiments were repeated two years following on the farm of Mr. Fauchet, one of the commission, at Boisquilaume, in the department of the Seine Inferieure.

The results arrived at by this commission are--1st. That it is not best to sow seed without steeping. 2nd. That it is best to make use of the sulphate of soda and lime process, inasmuch as it is more simple and economical, in no way injurious to the health, and yields the soundest and most productive wheat. 3rd. That the use of a.r.s.enic, sulphate of copper, verdigris, and other poisonous preparations, should be interdicted by the government.--("Gardeners'

Chronicle," January 6th, 1849, pp. 10 and 11.)

_Composition of wheat and wheat flour, and the various modes of determining their nutritive value_.--In my former report it was stated that the a.n.a.lyses of the various samples of wheat, the results of which were there given, had been chiefly directed to the determining the amount of rough _gluten_ which they contained. My reasons for adopting this plan, and the arguments in favor of its general accuracy, as compared with other modes of a.n.a.lysis, and especially that by which the ultimate composition is ascertained, were also detailed. A more full examination of this subject has served only to strengthen the opinion already expressed, that for the great purpose to be answered by these researches, the process which I have adopted is, to say the least, as free from objection as any other, and if carefully and uniformly carried out, will truly represent the relative values of the several samples of wheat flour.

As this is a matter of much consequence in a practical point of view, I trust I shall be excused for introducing some additional facts in regard to it.

The term _gluten_ was originally applied to the gray, viscid, tenacious, and elastic matter, which is obtained by subjecting wheat flour to the continuous action of a current of water. But it appears that this is a mixture of fibrine and caseine, with what is now called _glutine_, and a peculiar oily or fatty matter. Now these substances may be separated from each other, but the processes employed for this purpose are tedious, and to insure accuracy the various solvents must be entirely pure--a point which, especially in the case of alcohol and ether, is not ordinarily easy to be attained. This will be rendered still more evident by a reference to a French process, which will hereafter be noticed.

But were it much less difficult in every case accurately to separate the const.i.tuents of gluten, it would not, in my opinion, be of the least practical utility. It is to the peculiar mechanical property of this gluten that wheat flour owes its superior power of detaining the carbonic acid engendered by fermentation, and thus communicating to it the vesicular spongy structure so characteristic of good bread.[37] It may also be added, that the results of more than one hundred trials have satisfied me that a diminution or loss of elasticity in the gluten is the surest index of the amount of injury which the sample of flour has sustained. Whether, therefore, the sample contains a certain proportion of nitrogen, or whether it contains alb.u.men, fibrine, and caseine in sufficient quant.i.ty, it may still want the very condition which is essential to the manufacture of good bread. My objection, therefore, to the mere determination, however accurate, of the proportion of nitrogen contained in wheat flour, or of the various principles which form the gluten, is, that it does not represent the value of the various samples for the only use to which they are applied, viz., the making of bread. The remarks of Mulder, the celebrated Dutch chemist, upon the subject of manures, are so applicable to this point that I cannot refrain from quoting them. "It has," he says, "become almost a regular custom to determine the value of manures by the quant.i.ty of nitrogen they yield by ultimate a.n.a.lysis. This method is entirely erroneous; for it is based upon the false principle, that by putrefaction all nitrogeneous substances are immediately converted into ammonia, carbonic acid, and water! But these changes sometimes require a number of years. Morphine, for example, is prepared by allowing opium to putrefy; and the process for preparing leucin, a substance which contains 10.72 of nitrogen, is to bring cheese into putrefaction. Cheese, therefore, does not perhaps in a number of years resolve itself into carbonic acid, ammonia, and water, but produces a crystalline substance, which contains no ammonia. Hence the proportion of nitrogen yielded by manures is not a proper measure of their value, and therefore this mode of estimating that value ought to be discontinued."[38] We infer, therefore, that the proportion of nitrogen furnished by food of various kinds is not the true measure of their nutritious value, and cannot for practical purposes take the place of that process by which the amount of rough gluten is determined.

No better ill.u.s.tration can be given of the uncertainty which attends the inferences drawn from the ultimate composition, than the fact heretofore stated in regard to hay, the nutritive value of which is placed in the tables containing the results of these a.n.a.lyses, at a figure nearly the same as that of ordinary wheat flour.[39] In the paper on the "Composition of Wheat," by M. Peligot--(" Comptes Rendus," February 5th, 1849)--to which I have already referred, the author gives the results of the various a.n.a.lyses which he has made, and details the process he adopted.

Aware of the complex and difficult nature of the examination as conducted by him, he seems to doubt in regard to some of the results given in his tables In the fourteen samples which he a.n.a.lysed, the proportion of water ranges from 13.2 to 15.2, which is a rather higher average than is yielded by our American samples, especially those which have not been s.h.i.+pped across the Atlantic. Of the nitrogenous matter, soluble and insoluble, the proportions range from 9.90 per cent, to 21.50 per cent.; the former being from a sample of very soft and white French wheat; the latter from a very hard wheat with long grains, from Northern Africa, cultivated at Verrieres. Another sample from Egypt yielded 20.60 per cent, of these nitrogenous matters, both of which are very remarkable proportions.

In describing the process for ascertaining the amount of insoluble nitrogenous matters, this author adverts to their estimation either by the quant.i.ty of nitrogen gas furnished, or of ammonia formed, the last being preferred for substances, which, like wheat, contain only a few hundredths of nitrogen. The results which he obtained by this method were compared with those yielded by the direct extraction of the gluten by softening the farina under a small stream of water.

"These results," says he, "differ but little from each other when we operate upon wheat in good condition, although the gluten which we thus obtain holds some starch and fatty matter, while the starch which is carried away by the water contains also some gluten." The loss and gain, as I have already explained, and as has been proved by these and other comparisons, are nearly balanced, and the amount of rough gluten will therefore afford a fair exhibit of that of the insoluble nitrogenous matters in this grain.

The salts in the samples of wheat a.n.a.lysed by M. Peligot, were either wanting or were in small proportion; while the amount of fatty matter ranged from 1.00 to 1.80 and 1.90 per cent.

These results agree very well with those which I have obtained. But it is probable that the proportion is liable to great variation, inasmuch as it is inferred that the fatty matter originates from starch through its exposure to the general deoxidising influence which prevails in plants.[40] There are also many difficulties attending the accurate determination of this matter, and which are probably the cause of the higher proportion often given. It is properly remarked by M. Peligot that the ether employed in this process should be free from water, and that the flour ought also to be very dry. By neglecting these precautions, we separate not only the fatty matter, but also a certain amount of matters soluble in the water, which is furnished as well by the wheat as by the ether.

It would not, I think, be difficult to point out some incorrect views entertained by this chemist, and more especially those which relate to the fatty matter. Some of his processes for the separation of various substances, if not faulty, require so many conditions for success as to render the results, at least in other hands, exceedingly uncertain.

But the capital error which he has committed is that concerning the bran, already adverted to, which he considers injurious to the flour, chiefly in consequence of the large proportion of fatty matter which it contains.

In regard to the soluble nitrogenous matter usually called alb.u.men, from its resemblance to the animal substance of the same name, I have to remark that in my trials the proportion has been found to be considerably less than that often given in tables of the composition of wheat. In one sample it was found to be as low as 0.15 per cant., in another it did not rise above 0.20 per cent. The amount was usually so inconsiderable, that I did not think it worth while to r.e.t.a.r.d the progress of the work by following out processes which could add little to the utility of these investigations.

Although much time and labor have been expended upon the a.n.a.lyses of the ash of plants, I have but slight confidence in the results heretofore given. The difficulties which attend the obtaining the ash in a proper condition, and the fact that the products of all the organs and parts of the plants have been a.n.a.lysed together, must necessarily impair the accuracy of the experiments, and render the inferences drawn from them of uncertain value. Much, indeed I may say almost everything, still remains to be done in this department of agricultural chemistry.

_Weight of wheat as an index to its value_.--Much has been said in regard to the relative weights of the bushel of wheat of different varieties or under different modes of culture.

As ordinarily determined, this weight ranges from fifty-six to sixty-five or sixty-six pounds, being in a few cases set down somewhat higher. It is said also that the bushel of wheat weighs less in some years than it does in others, and that the difference often amounts to two, or three, or even four pounds. Though this may seem of comparatively little consequence for a few bushels, yet, for the aggegate of the wheat crop of the United States, or for a State, or even a county, it makes a great difference. Thus, were we to estimate the product of one year in the United States at one hundred and ten million bushels, weighing fifty-six pounds to the bushel, and another year at one hundred and eight million bushels, weighing sixty-two pounds, the difference in favor of the latter, though the least in quant.i.ty, would amount to five hundred and thirty-six million pounds in weight, or more than one million and a quarter of barrels of flour.--(Report of the American Commissioner of Patents for 1847, p. 117.)

It may be remarked, however, that it is not after all so easy to determine with accuracy the weight of a bushel of wheat, nor to decide upon the circ.u.mstances which have an influence in increasing the density of a grain of wheat. If the microscopical representations of wheat are to be relied on, it is probable that the increase in the density of wheat depends upon the increase in the proportion of gluten. I have found in several cases that, the proportion of water being the same, those samples of wheat which contain the largest proportion of gluten exhibit the highest specific gravity, or, in other words, will yield the greatest number of pounds to the bushel. But the weight of wheat will be influenced by the proportion of water which it contains; the drier the grain, the greater is its density; a fact which may account for the difference which has been observed in the weight of wheat in different seasons. If this is the cause, the calculation above given in reference to the United States is fallacious--but if the amount of gluten is _actually_, instead of _relatively_, increased by peculiarities in seasons, it is no doubt correct.

I have devised a series of experiments to test the accuracy of the statements made upon this point, but have not yet had leisure to complete them.

_General conditions from the a.n.a.lyses of wheat flour_.--The large number of a.n.a.lyses which I have made, and the uniformity of the processes pursued, enable me to draw some general conclusions which it may be useful to present in a connected form.

1. In the samples from the more northern wheat-growing States, there seems to be little difference in the proportion of nutritive matter that can be set down to the influence of climate. Thus, the yield of the wheat from Michigan, Wisconsin and Iowa, is scarcely inferior to that from New York, Indiana, and Illinois, although the two latter are somewhat farther south. Local causes, and more especially the peculiarities of culture and manufacture, have more influence, within these parallels of lat.i.tude, than the difference of mean temperature.

2. The samples from New Jersey, Lower Pennsylvania, the southern part of Ohio, Maryland (probably Delaware), Virginia, the Carolinas, and Georgia,[41] contain less water and more nutritive matter than those from the States previously enumerated. That the samples from Missouri, which is included within nearly the same parallels of lat.i.tude as Virginia, do not exhibit so high an average of nutritive matter as those from the latter State, must be ascribed princ.i.p.ally to a want of care in the management of the crop, and perhaps also in the manufacture of the flour. Virginia flour, for obvious reasons, maintains a high reputation for s.h.i.+pment.

3. The difference in the nutritive value of the various samples of wheat depends greatly upon the variety, and mode of culture, independently of climate. The correctness of the former statement is shown by the much larger proportions of gluten yielded by many of the samples of _hard_ wheat from abroad, the Oregon wheat in Virginia, and a variety of Illinois wheat, &c. And in regard to the effect of particular modes of culture, the various a.n.a.lyses of Boussingault may be referred to, and that in my table of a sample from Ulster county, New York.