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 asserts, 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, substitutes for animal food. Tubers, roots, and even the seeds of the cereal grasses, 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 quantities. 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 associate their potato dish with a large quantity of sour or curdled milk; in Ireland with buttermilk. "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 quantity of cheese. Rice is often cited as one of the most nourishing 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 quantity 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 quantity 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 analysis, 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 illustration 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 quantity 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 mass 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 quantity 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 quantities 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 arsenic, 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 smut 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 arsenic, 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 analyses 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 analysis, 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.