The Chemistry of Food and Nutrition

by A. W. Duncan

A delicately balanced, fine-grained, high-toned mind and body responds to every tender influence, and is painfully jarred by that which is coarse. To such, fruits and delicately flavoured and easily digested foods are doubtless best and conducive to purity and clearness of thought. A coarse-grained, badly poised, roughly working body and spirit, is non-responsive except to loud or coarse impulses; and such a one's appetite is gratified, not by simple but by coarsely seasoned foods.

A person who is accustomed to a stimulating dietary of flesh-foods, especially if well-seasoned, finds a simple diet unsatisfying. Should such persons dine off simple vegetarian food, there is a tendency to over-eating. The less stimulating food fails to rouse the digestive organs and to appease the appetite; although an ample supply of nourishment be consumed. This is the reason why so many imagine that it is necessary to eat a larger quantity of food if it be vegetable. Should a distressing fulness and flatulence result from their over-feeding, they lay the blame to the vegetarian dietary instead of to themselves. Most persons, on changing to a vegetarian dietary, commence by imitating flesh dishes in appearance and flavour and even in the names. There is the additional inducement that the food may be attractive and palatable to friends who lack sympathy with the aesthetic and humane principles of the diet. After a while many of them incline to simpler flavoured foods. They revert to the unperverted taste of childhood, for children love sweets, fruits, and mild-flavoured foods rather than savouries. One who loves savouries, as a rule, cares much less for fruits. By compounding and cooking, a very great variety of foods can be prepared, but the differences in taste are much less than is usually, supposed. The effect of seasoning instead of increasing the range, diminishes it, by dulling the finer perception of flavours. The predominating seasoning also obscures everything else. The mixture of foods produces a conglomeration of tastes in which any particular or distinct flavours are obscured, resulting in a general sameness. It is often stated that as an ordinary flesh-eater has the choice of a greater range of foods and flavours than a vegetarian, he can obtain more enjoyment, and that the latter is disagreeably restricted. Certainly he has the choice, but does he avail himself of it to any considerable extent? No one cares to take all the different kinds of food, whether of animal or vegetable that are possible. Of edible animals but a very few kinds are eaten. A person who particularly relishes and partakes largely of flesh-foods will reject as insipid and unsatisfying many mild-flavoured foods at one end of the scale. The vegetarian may abstain from foods at the opposite end of the scale, not always from humane reasons, but because they are unpleasant. Thus there may be little to choose between the mere range of flavours that give enjoyment to each class of persons. The sense of taste is in its character and range lower than the sense of sight and hearing. The cultivation of the taste for savouries seems to blunt the taste for fruits and the delicate foods. The grass and herbs on which the herbivora subsist, seems to our imagination of little flavour and monotonous; but they eat with every sign of enjoyment, deliberately munching their food as though to get its full flavour. In all probability they find a considerable range of flavours in the great varieties of grasses commonly found together in a pasture.

Our elaborate cooking customs entail a vast amount of labour. They necessitate the cost, trouble and dirt from having fires in great excess of that required for warmth: the extra time in preparing, mixing and attending to food which has to be cooked: and the large number of greasy and soiled utensils which have to be cleaned. Cooked savoury food is generally much nicer eaten hot, and this necessitates fires and attention just previous to the meal. We have already said that soft cooked food discourages mastication and leads to defective teeth. Our elaborate cookery is mainly due to our custom of eating so largely of flesh, whilst the eating of flesh would receive a great impetus on the discovery of the art of cooking. Flesh can only be eaten with relish and with safety when cooked. Such a large proportion of it is infected with parasites, or is otherwise diseased, that it would he dangerous to eat it raw, even were it palatable in such a state. In those countries where man eats flesh in a raw or semi-cooked form, parasitic diseases are common. There is not the least doubt that our habit of eating so much cooked food is responsible for much over-eating, hasty eating, dyspepsia and illness. In regard to the making of bread, porridge, and many other comparatively simple prepared foods, the advantages of cooking seem overwhelmingly great. With our present imperfect knowledge and conflicting opinions, it is impossible to arrive at any satisfactory conclusion, and the whole question requires careful and impartial investigation. Experiments have been made with animals, chiefly pigs, with cooked and uncooked clover, hay, corn, meal, etc. (U.S. Department of Agriculture). It was found that the food was more or less diminished in digestibility by cooking. At least 13 separate series of experiments with pigs in different part of the country have been reported. In 10 of these trials there has been a positive loss from cooking the food. The amount of food required to produce in the animal a pound gain in weight was larger when the food had been cooked than when it was given raw. In some cases, the increased quantity of food required after cooking was considerable.

Those who live on uncooked food contend that a smaller quantity of nourishment is required. As uncooked food requires more mastication and is eaten more slowly, there is a better flow of saliva and time is given for the digestive organs to be gradually brought into complete action, and finally for the appeasing of the appetite. In the case of the members of the fruitarian family, whose food was uncooked, and of whom we have previously written, the quantity of nutriment taken was much less than that thought necessary, even after making full allowance for their small stature and weight.

Meat Extracts.—Justus von Liebig, the great German chemist, was the first to attempt to make these on the commercial scale. He described a method in 1847, and this not proving satisfactory, another one in 1865. He stated that the only practicable plan on a manufacturing scale, was to treat the chopped flesh with eight to ten times its weight of water, which was to be raised to 180° F. In another passage he says it is to be boiled for half-an-hour. After straining from all the undissolved meat fibre, etc., and carefully cleansing from all fat, the decoction is to be evaporated to a soft extract; such a preparation is practically free from albumin, gelatin and fat; all the nutritive principles except the saline matter having been extracted. Liebig states that 34 pounds of meat are required to produce 1 pound of extract. In 1872, he wrote "neither tea nor extract of meat are nutritive in the ordinary sense," and he went on to speak of their medicinal properties. Druit, in 1861, in describing the effect of a liquid preparation of meat, states that it exerted a rapid and stimulating action on the brain, and he proposed it as an auxiliary and partial substitute for brandy, in all case of great exhaustion or weakness attended with cerebral depression or despondency. In like manner, a feast of animal food in savages, whose customary diet was almost exclusively vegetable, has been described by travellers as producing great excitement and stimulation similar to that of intoxicating spirits. Similar effects have been observed from a copious employment of Liebig's extract. Voit asserts, from the results of his experiments, that extract of meat is practically useless as a food, and other authorities are quite of the same opinion, although they may value it as a stimulant and drug. _The Extra Pharmacopæia_, 1901, states that "Liebig's Extract or Lemco consists of creatin, creatinin, globulin and urea, with organic potash and other salts. It has been much over-estimated as a food either for invalids or healthy persons; still it is often valuable as a flavouring to add to soups, beef-tea, etc., and it is a nerve food allied to tea." Meat extracts stimulate the action of the heart and the digestive processes, but as in the case of other stimulants there is a succeeding period of depression. The British Medical Journal says that the widespread belief in the universal suitability of concentrated beef-tea is frequently responsible for increasing the patient's discomfort, and is even capable in conditions of kidney inefficiency, of producing positive harm. Some of the meat bases, the leucomaines, have been found to possess marked poisonous effects on the body. The manfacturers of meat extracts continue to mislead the public by absurdly false statements of the value of their products. They assert that their extracts contain the nutritive matter of 30, 40 or 50 times their weight of fresh meat, or that one or two meat-lozenges are sufficient for a meal. One company, asserts by direct statement, or imply by pictorial advertisement, that the nutritive matter in an ox can be concentrated into the bulk of a bottle of extract; and another company that a tea-cup full is equivalent in food value to an ox. Professor Halliburton writes: "Instead of an ox in a tea-cup, the ox's urine in a tea-cup would be much nearer the fact, for the meat extract consists largely of products on the way to urea, which more nearly resemble in constitution the urine than they do the flesh of the ox." Professor Robert Bartholow has also stated that the chemical composition of beef-tea closely resembles urine, and is more an excrementitious substance than a food. Those whose business it is to make a pure meat-broth, for the purpose of preparing therefrom a nutrient for experimenting with bacteria, cannot fail to recognise its similarity both in odour and colour to urine. Little consideration is needful to show the untruthfulness and the absurdity of the statements made by manufacturers as to the food value of these extracts. Fresh lean beef contains about 25 per cent. of solid nutriment and 75 per cent. of water. If lean beef be desiccated, one pound will be reduced to four ounces of perfectly dry substance; this will consist of about 80 per cent. of proteid matter and nearly 20 per cent. of fat including a little saline matter and the extractives. This is as far as it is possible to concentrate the beef. If it were possible to remove, without interfering with the nutritious constituents, the membraneous matter, the creatin, creatinine and purin bodies, we should reduce it to a little less than four ounces. It is very remarkable that the most nutritious matter of the beef, the muscle substance or proteid and the fat, are rejected in making Liebig's extract, whilst the effete or waste products are retained. In Bovril and some other preparations, some meat fibre has been added with the object of imparting a definite food value. Hence in some advertisements, now withdrawn, it was alleged that the preparations were immensely superior in nutritive value to ordinary meat extracts. The Bovril Company extensively circulated the following:—"It is hard for ladies to realise that the beef tea they make at home from the choicest fresh beef contains absolutely no nourishment and is nothing more than a slight stimulant. It is so, however, and many a patient has been starved on beef tea, whether made from fresh beef or from the meat extracts that are sold to the public. From these Bovril differs so much that one ounce of its nutritious constituents contains more real and direct nourishment than fifty ounces of ordinary meat extract." If analyses of meat extracts are referred to, it will be seen that the principal part of Bovril is the meat bases and other things common to all such extracts, and which the Company in their circular so emphatically condemn. If the meat fibre, which is the principal, if not the sole difference, is the only nourishing constituent, it is difficult to see the advantage over ordinary beef, which can be procured at a very small proportionate cost. Concerning this added meat fibre, C.A. Mitchell, in "Flesh Foods," writes: "As this amounts to at most some 8 or 10 per cent., it is obvious that a large quantity of the substance would be required to obtain as much unaltered proteid as is contained in an egg. On the other hand, it has been pointed out that there is nothing to show that flesh powder suspended in meat extract is more digestible than ordinary flesh in the same fine state of division, whilst the amount of flesh bases, the principal stimulating agents, is correspondingly reduced." Concerning added albumin and meat fibre, A.H. Allen, in "Commercial Organic Analysis," vol. iv., writes: "The amount of these constituents present in such a quantity of meat extract as is usually, or could be, taken at a time, is too insignificant to give it any appreciable value as nutriment." Notwithstanding such statements by analysts and others, Bovril is advertised to contain "the entire nourishment of prime ox-beef." The great extent of the extract of meat trade is shown by a circular issued by the Lemco and Oxo Company. They give the number of their cattle killed since 1865 as 5,550,000; stock of cattle 160,000; employees in works, farms and branches, 3,200. This is only one out of many such companies. It is a sad thing that myriads of animals should be slaughtered with all the horrible and brutalising surroundings of the slaughter-house to such a purpose—the nutritious matter being nearly all wasted. Reliance on these extracts is responsible for much sickness and death. Instead of their preventing colds, influenza, and other complaints as is professed, they predispose to them by overloading the body with waste products, taxing the excretory organs and reducing the vitality. The following analyses of meat extracts are by Otto Hehner:—

Some of the "Liebig's Extract of Meat" so called, contains yeast extract; some even, is almost entirely, if not altogether made from yeast. The latter can be manufactured at a very low cost from brewers' and distillers' waste products, and there is a strong incentive for unscrupulous dealers to substitute it secretly. Artificial meat extracts prepared from yeast have the appearance and taste of meat extracts, but some, at least, have a considerably sharper flavour. In one method of manufacture common salt is added, and this renders it unfit for use in more than very small quantities as a flavouring. J. Graff has made analyses of ten yeast extracts, and contrasted them with meat extracts (see Analyst 1904, page 194), and says, "It will be seen that the chemical composition of yeast extract does not greatly differ from that of meat extract." Yeast extracts contain purin bodies, and are probably equally as injurious as meat extracts. Such strong and rank flavours (the odour is suggestive to us of putrefaction) should be discouraged by those who would cultivate a refined taste in food.

Flesh Bases and Waste Products.—As the result of destructive metamorphosis or the wearing out of the body, there remain certain waste products which have to be expelled as soon as is possible. Their retention and accumulation would soon produce death. A part is expelled by the lungs as carbon-dioxide, or as it is generally though less correctly termed, carbonic acid. Upon the breaking down of the complex proteid and other nitrogenous matter, the nitrogen is left in comparatively simple combinations. These effete nitrogen compounds are commonly termed flesh bases or nitrogenous extractives. They exist in small quantity in flesh meat, but are concentrated and conserved in the making of beef-tea or beef-extract. The spleen, lymphatic and other glands, and especially the liver, break these down into still simpler compounds, so that the kidneys may readily separate them from the blood, that they may pass out of the body. By far the largest part of this waste nitrogen is expelled from the bodies of men and many other mammals in the form of urea. Pure urea is an odourless transparent crystalline substance, of cooling saline taste like nitre. It is soluble in an equal volume of water, and is expelled from the body with great ease. In the herbivora the nitrogenous waste takes the form of another body called hippuric acid. The nearly solid light-coloured urinary excretion of birds and serpents consists of urates; this is uric acid in combination with alkalies. In man, in addition to the urea excreted, there is also a little hippuric and uric acid or compounds of these. Uric acid is a transparent colourless crystalline body almost insoluble in water but soluble as urates in the presence of alkalies. As deposited from urine it is of a dull red sand-like appearance, as it has a great affinity for any colouring matter that is present.

It is only possible to make a brief reference to the chief organic bases. The xanthine bases are closely related to uric acid. Some of these occur in small quantity in the urine and animal tissues, others, such as caffeine, occur in plants. Creatine is a constant constituent of muscle substance. In fowl's flesh there is said to be 0.32 per cent., in cod-fish 0.17 per cent., and in beef 0.07 per cent. Creatinine is produced from creatine with great facility; it exists in urine. Both creatine and creatinine are readily soluble in water. A series of bases, closely allied to creatinine have been isolated from the flesh of large animals by A. Gautier; they are known as Gautier's flesh bases. When administered to animals, these act more or less powerfully on the nerve centres, inducing sleep and in some cases causing vomiting and purging in a manner similar to the alkaloids of snake venom, but less powerfully than the ptomaines. These bases are formed during life as a result of normal vital processes and are termed leucomaines.

Another class of bases of an alkaloidal nature, are termed ptomaines; these differ from the leucomaines, being produced by putrefactive or bacterial agency from dead flesh. The poisoning which has occasionally resulted from the eating of sausages, pork-pies, tinned meats, etc., is due to their having contained ptomaines.