Food.

Food. Although the word 'food' is generally taken to indicate those solid matters, such as bread, meat, &c., which are consumed by a person for the nourishment of his body, yet it is convenient to use the term with a much wider significance. Under the term food we are forced to speak of all matters ingested for nutritive purposes, irrespective of their physical conditions, and to include beverages of various kinds, and even the air we breathe. There is the following very simple reason for this somewhat extended definition of the word. Water is the basis of all beverages, and no ordinary solid food is without some water, while on the other hand most beverages, wine, beer, tea, &c., contain solid matter dissolved in water. Air, as every one knows, is a vital and ever-pressing necessity, and its action within the body is eminently nutritive. The tissues of the body consume its oxygen as well as the nutritive parts of beef and mutton; and air we must therefore include within our extended definition.

The classification of food into solid food, beverages, and air would, however, be an unsatisfactory one. The chemist has been able to divide the food-stuffs, as we may call them, into classes, by sorting into groups substances which have similar chemical and physical properties. This arrangement has the advantage that members of the same class have nearly always similar properties as regards their nutritive functions.

THE VARIOUS KINDS OF FOOD-STUFFS.

The Nitrogenous Foods.—These all contain nitrogen, and, inasmuch as during life nitrogen is invariably, and under all circumstances, excreted by the body, it must be replenished by nitrogenous food-stuffs. The proteids (albuminoid substances) are found both in the animal and vegetable world. Among animal proteids are the white of egg, the vitellin of the yolk, myosin from muscle (flesh of meat), fibrin and albumen from blood, and gelatin from bones. In the vegetable world vegetable albumens and globulins are present, and in the grains and seeds of plants they are found in quantity. Nitrogenous extractives are found in the muscles (flesh) of animals, and are probably of great value, chiefly as stimulants. Beef-tea is an extract of these from the muscle of the ox, and they are found in rich animal soups.

The Carbohydrates.—These are food-stuffs containing carbon, oxygen, and hydrogen, but no nitrogen. Moreover, the oxygen and hydrogen are present in the proportions which form water. The vegetable world furnishes us with the most important carbohydrates. These are the various starches and dextrines. Then we have the sugars—cane-sugar, grape-sugar, sugar of milk or lactose, &c. The flesh and other eatable parts of animals are poor in carbohydrates; nevertheless the latter are found there. Glycogen or animal starch is widely distributed, although, except in the liver, it is present in small quantity.

Fats and Oils.—These substances, of a very high nutritive value, are found in both the animal and vegetable world. In vegetables they are especially abundant in seeds and fruits. In the animal world we find them in the tissues under the skin, and in many animals, such as whales, seals, &c., the blubber, as it is called, is present in enormous amount. The liver is generally found to contain a great deal of fat, as is also the tissue round the kidneys, and round other abdominal organs. The chief fatty matters present are olein, stearin, and palmitin.

Vegetable Acids.—The action of these substances as food-stuffs, though important, is not altogether understood; but their withdrawal from the food may lead to serious inconvenience. The most important vegetable acids are tartaric, oxalic, citric, acetic, and malic.

Inorganic Salts.—Of these the most important is common salt, or sodium chloride. It is present in small quantities in all foods, but in addition man requires as a rule a still larger quantity. It greatly assists digestion, and probably is necessary for the formation of the gastric juice. Whereas it can pass through the system if taken in large quantities, yet a certain amount is required by the body to establish within it those conditions under which alone life is possible. Thus, many of the proteids would suffer complete alteration were it possible to abstract all the salt from the body, and the blood would become at once a turbid fluid which would rapidly cease to flow. In addition to sodium chloride there are many other salts required, such as potassium chloride and the phosphates of calcium and magnesium, the latter for the formation of bone. Iron salts are required for the formation of the colouring matter of the blood.

Water.—This all-important substance is taken in its natural form as spring, river, well, or rain water. In all cases certain inorganic salts are held in solution, which vary in their nature and quantity with the soil with which the water has come in contact. Organic (both animal and vegetable) matter may be present, especially in river and shallow well water. In addition, water is present in almost every kind of solid food, as well as in liquid foods and beverages. Bread, meat, cheese, potatoes, all contain a large quantity of water, and such substances as flour and biscuits are rarely free from a trace of it. Its importance for the needs of the economy are at once apparent when we recollect the large amount daily excreted by the lungs, the kidneys, and the skin, all of which require replenishing.

Air.—From the atmosphere we breathe oxygen is obtained, without which the other classes of food-stuffs would avail us little. Their destination is, in fact, to meet with this oxygen, and suffer changes called 'oxidation changes' within the tissues of the body.

SOURCES OF THE FOOD-STUFFS.—The Carcasses of Animals.—From the carcasses of animals we obtain meat and bones and fat, all of which have an important nutritive value. Cartilage, gristle, and yellow elastic tissue (pax-wax) are of almost no utility. Meat consists of from 70 to 80 per cent. of water, and the rest of proteids, extractives, fats, salts, and indigestible substances. The proteids of meat form about 20 per cent. of the whole; they are easily digestible, more so perhaps than are the vegetable proteids. Amongst the proteid fibres of the meat a certain amount of fat is generally lodged, and here and there it is collected in larger masses. The percentage quantity varies immensely, but even in lean meat there is on an average 2 per cent. of fat present. The extractives of meat are valuable stimulants of digestion, and the salts, chiefly chlorides and phosphates, are very abundant. The flesh of domesticated animals, such as oxen, sheep, and pigs, is especially rich in fat. The same may be said of fowls, ducks, and geese. The flesh of wild animals and birds contains less fat, and very little is ever present in the flesh of fish. The flesh of animals is almost invariably eaten after cooking. In this case the proteids are coagulated, the fibrous tissue of the meat is softened and rendered more digestible, and the savoury qualities of the meat are developed.

Meat may be cooked directly after killing, and in this case it is tender and very palatable. If the animal be kept for even a few hours the meat becomes hard owing to death coagulation; cooked at this stage it is tough and indigestible; it requires to be kept until it softens again. If kept for some time meat putrefies and becomes high. Game is generally eaten in this condition, and it is readily digested, and admirable in flavour. It is, however, apt to disagree with many people, and even fatal consequences may follow its consumption. High meat is putrid meat; the proteids have in part decomposed, but the remainder is partly in the very digestible form of a peptone proteid. The meat contains microscopic organisms termed Bacteria (q.v.), and is full of their excretions (see PTOMAINES). These ptomaines are in all probability the cause of both the intestinal troubles and the actual poisoning which may follow the consumption of high meat, although at present we are not in a position to say why, under ordinary circumstances, it may be as a rule consumed with such impunity. Their poisonous action seems not to be destroyed by thorough cooking. The same may be said of the fatal consequences which sometimes follow eating fish, lobsters, crabs, and shell-fish which are not as fresh as they should be. In other cases, from as yet unknown causes, mussels, oysters, and other shell-fish produce bad dyspepsia, nettle-rash, and even graver symptoms, although they are eaten perfectly fresh. Many fish, especially during the breeding season, are quite unpalatable or even poisonous, apart from putrefactive changes. These fish are for the most part inhabitants of the tropical seas.

Idiosyncrasy plays a very important part in our selection of animal foods. Many are unable to eat veal, pork, high game, and certain kinds of fish. One medical man known to the writer can eat eggs à la coque, but vomited at the smell of a poached egg. Another can only eat freshly killed meat; if it has been hung a day or two, although he cannot distinguish the difference by means of the palate, yet he suffers afterwards from violent diarrhoea.

Diseased meat is always to be avoided, and it is probable that many affections as yet unrecognised are derived from eating the flesh of animals not in perfect health. There is, however, a great difference of opinion on this subject: many authorities at the present day trace even cases of poisoning to the eating of the flesh of animals suffering from black-quarter, smallpox, foot-and-mouth disease, cattle-plague, and anthrax; while it is certain on the other hand that the flesh is frequently eaten without any traceable ill consequences. No ill effects have been proved to follow the consumption of the flesh of pigs suffering from typhus and scarlet fevers. Nevertheless it cannot but be a sound principle to follow, that the flesh of healthy animals should alone be eaten; it is well to err on the safe side. Moreover, no one questions the fact that the flesh of the pig affected with trichina spiralis must be avoided. The parasites are not at all readily killed by cooking, and very dangerous febrile symptoms are produced by the action of the young trichinae which wander into the tissues. Tapeworm is also produced by the consumption of the flesh of the pig and ox, although if the flesh be thoroughly cooked the danger is greatly diminished.

Bones of animals are very important articles of food. In the interior of the shafts one finds the yellow marrow, consisting of fat of a very savoury taste. At the ends of the bones is situated the red marrow, which is practically devoid of fat, but is rich in nitrogenous extractives. The whole bone, too, is porous, and boiling is able to extract from its interior a rich supply of nitrogenous extractives. Hence bones are useful for making soups, which we may look upon as hot decoctions of salts and extractives, having a useful stimulating action, but not of any great nutritive value, unless thickened by the addition of pieces of meat or vegetables, which should be served up with the soup. The bone itself consists of a gelatin-yielding substance termed collagen, which is chemically united with earthy inorganic salts. This gelatin may be removed by prolonged boiling, and is used for making jellies, and for various other purposes.

Cereal Grains.—These are very important articles of food, and are largely used by mankind in nearly all parts of the globe. The most important cereal grains are those of wheat, oats, rye, barley, rice, and maize. They form very condensed articles of food, containing little water, and consisting of highly nutritive solid matter. They all contain an abundance of starch, together with smaller quantities of dextrine and sugar. Proteid matters are also present in no inconsiderable amount, consisting chiefly of insoluble substances, such as gluten-casein, gluten-fibrin, gliadin, together with some soluble albumen. The cereals are as a rule deficient in fat and salts.

Wheat-flour and Bread.—Wheat is rich in albuminous matter, containing about 12 per cent. It contains about 70 per cent. of starch, and very little fat. The grain is crushed and separated into flour and bran. With the loss of the bran the flour loses some fat, salts, and nitrogenous matter; on the other hand, bran is irritating to the digestive mucous membrane. Whole-meal bread is therefore more nourishing, but is apt to disagree.

If flour be mixed with water it forms a sticky dough or paste. This consists of gluten, a nitrogenous substance of a sticky nature, by which the granules of starch are held together. On heating this dough, with or without admixture of eggs, milk, &c., pastry, biscuits, &c. are made. Macaroni is made by forcing dough through small apertures during the application of heat. Bread is dough inflated with carbon dioxide, which gas may be generated in the dough itself, or may be driven into it by pressure. Yeast has the property of converting sugar into alcohol and carbon dioxide. If therefore yeast be mixed with dough which contains a little sugar, this ferments, and the carbon dioxide causes the dough to swell up. Baking powders are used for the same purpose; they consist of substances which yield carbon dioxide during the baking process. In Dauglish's process carbon dioxide is forced into the bread under pressure, and bread so prepared is termed 'aerated.' When flour is converted into bread much of the starch is converted into the more easily digested dextrine, and the albumens are coagulated and otherwise changed. It is rendered soft and open, readily permeable by the digestive juices. One hundred pounds of flour yield about 135 lb. of bread.

Oats and Oatmeal.—Oats have this advantage over wheat, that they contain more fat and more saline matter. They may be looked upon on this account as more valuable food, when the diet is limited to a few articles only. They are ground into oatmeal, from which porridge may be made. Oatmeal boiled with a large quantity of water, so as to form a drink, is highly spoken of by Parkes. It is capable of forming a much more sustaining drink than perhaps any other, and is much advocated for the use of labourers, especially for those engaged in harvesting or in other labour, where great exertion has to be made in a short space of time.

Barley, Maize, and Rye.—These are very nutritious, the maize containing about 6 per cent. of fat, in addition to albuminous and starchy matter. Rye and barley are apt to produce intestinal irritation.

Rice.—This grain is poor in nitrogen, and contains little fatty matter; so that those who subsist almost entirely upon it are obliged to supplement its deficiencies by admixture with fat, and with proteid matter either in the form of milk or legumes. It should not be cooked by any boiling process, inasmuch as during the process it loses much of its nutritive value, the albumens being in part dissolved away. It should be steamed in preference.

The Legumes or Pulses.—These include the peas, beans, and lentils. They are distinguished by containing large quantities of nitrogenous matter, and accordingly their chief utility is to supplement the deficiencies of starchy and fatty food. They are eaten with rice in India, and in England they form a favourite dish—'beans and bacon'—equivalent to the 'baked beans' of New England. The Mexicans, however, are the greatest consumers of beans (frijoles) in the world, although this vegetable is nearly equally popular throughout Central America; and the garbanzo, or chick-pea, fills the place of the potato in Spain. Lentil soup is a valuable food. The pulses are not readily boiled, and are not digested very easily.

Vegetable Roots.—Vegetable roots and tubers yield abundant food to man, of a highly nutritive quality, and containing as a rule a large quantity of starchy matter. The potato is one of the most important tubers. As it contains little nitrogenous and fatty matters, these must be added when the diet consists largely of potatoes. This tuber should be steamed rather than boiled; it is very digestible, especially when not too young. Since 1845, the year of the great potato disease, the plant has deteriorated, and, some maintain, is a less nutritive food than it had previously been. Arrow-root, which consists almost entirely of starch, and is largely adulterated with other forms of starch, cannot be considered in any other light than that of a single food-stuff, and in consequence it must always be used as an addition to other foods. The same remark applies to Tapioca (q.v.), and to sago, although this latter is obtained not from a root, but is cut away from the centre of the stems of several kinds of palm-trees. Other roots are the Jerusalem artichoke, containing sugar and nitrogenous matter, and turnips, carrots, and parsnips, containing starch, sugar, and a small quantity of nitrogenous matter. Beet-roots, mangold-wurzels, and radishes are all succulent roots, containing both starch and sugar.

Vegetables.—The most important vegetables are members of the cabbage tribe, amongst which may be mentioned the common cabbage, the red cabbage, cauliflower, Brussels sprouts, various kales, and broccolis. These have not a very high nutritive value, but they supply the economy with useful salts, and are in consequence very highly antiscorbutic. Much the same may be said for the lettuce, onion, mustard, cress, endive, &c.

Fruits.—These are of value chiefly on account of the sugar and vegetable acids they contain. The sugar is in a form which is readily absorbed; and, on account of the large quantity of vegetable acids, they have a very important antiscorbutic action.

Nuts., such as cocoa-nuts, walnuts, Brazil-nuts, are rich in oily and nitrogenous matter. They are not easily digested, however.

Beverages.—Water is the main constituent of every beverage. Most beverages contain solid matter, either in solution or in a state of suspension. We may divide beverages into nutritive and stimulating, the most useful ones combining both these properties. Perhaps the most important nutritive beverage is milk. It contains all the necessary food-stuffs, as is shown by the fact that the newly-born child can thrive on it alone. Its percentage composition is nitrogenous matter, 4 per cent.; fat, 4; milk-sugar, 5·2; salts, 8; water, 86 per cent. The composition varies in different breeds of cows. The Alderney cow yields a milk that is very rich in fat, while the milk of the long-horned cow is rich in casein. It varies too with the pasturage, and may even acquire poisonous properties. The peculiar taste of the milk from cows fed on turnips is well known to every one. The milk of the ass may frequently be taken by persons who are unable to digest cow's milk. Cream consists of the fat of milk, and is obtained by allowing freshly drawn milk to stand for some hours. The lighter cream floats to the surface, and may be removed. The name 'skimmed milk' is applied to the residue after removal of the cream. Butter-milk contains less fat than does skimmed milk. It is, however, of important nutritive value, as it contains much nitrogenous matter, salts, and sugar.

Tea, Coffee, and Cocoa are restorative beverages having a stimulating action. They have little nutritive value unless taken with milk and sugar. Tea contains an astringent substance—tannin, which causes the rough taste experienced when it is drunk without milk. The addition of a few drops of the latter substance prevents its astringency, by precipitating the tannin as an insoluble albuminous tannate. It should be made by pouring boiling water over the leaves; if the leaves are boiled in water they lose their aroma, and much astringency is developed. On account of its astringency tea slightly impedes digestion and lessens the action of the bowels. Theine is the active principle. Coffee has, roughly speaking, the same composition as tea. Its active principle is caffeine, and it contains a tannic compound and a characteristic volatile oil. As a beverage it is stimulating; but it retards digestion and the action of the bowels. Like tea, it is said to prevent tissue waste, and it increases the action of the skin. Cocoa is much more nutritive than either tea or coffee, as it contains starch and a large quantity of fat and proteid matter. Chocolate is prepared by adding sugar and flavouring matter to the cocoa. See also KOLA.

Alcoholic Beverages.—Alcohol is an article of food of some nutritive value, though perfect health is compatible with total abstinence (see ALCOHOL). Alcohol is undoubtedly oxidised within the body, although if taken in any quantity the excess is eliminated. Taken in reasonable quantity it stimulates the action of the heart, and probably raises slightly the temperature of the body; but it retards to some slight extent the action of the gastric juice. It is also a mental stimulant, producing exhilaration. In many alcoholic beverages a large quantity of saccharine matter is present, and these may in consequence hold a place as possessing high nutritive qualities. Such are beer and porter. Bitter principles, when present, as in beer, are gastric stimulants, and probably assist digestion by increasing the secretion of the gastric juice.

The Economics of Food.—In temperate climates when a pastoral people turn their attention to agriculture they become to a great extent vegetable feeders. Their diet no longer consists chiefly of the flesh and milk of animals, but in addition includes the use of a large proportion of grains, pulses, and other vegetable food-stuffs. The agricultural race in time displaces the pastoral one, for several reasons. In the first place, the very fact that the art of agriculture has been acquired indicates a greater mental development, certain to exercise its full weight in the struggle for existence. In addition, however, there is another and an equally potent reason. Vegetable matter is, and must always be, more economical as a food-stuff than animal matter. A given area of soil must always yield food-stuffs of a more nutritive value if that soil has been used to cultivate vegetables such as corn, oats, &c., to be eaten directly by man, than if it be used for the maintenance of any animal kept for the subsequent nutrition of man. The reason is very simple. A vegetable has a certain nutritive value—i.e. it will yield when eaten so much muscular energy, &c. If eaten by man it will directly administer to the energy of his body, and his muscles and brain will be nourished by it. If it be given to an ox part will no doubt go to the nourishment of the ox, and then, if the ox be eaten, to the nourishment of the man. The greater part, however, will be consumed by the ox to obtain materials for its own energy. Every step it takes, the perpetual movement of its jaws in chewing, the whisking of its tail to chase away a fly, these are all deductions to be made out of the nutritive value of its food, and the residuum alone, and that a comparatively small one, is what is obtained when the ox is consumed. So truly is this understood by practical men that they try to minimise these deductions to the greatest possible extent. They prevent as much movement as possible on the part of the animals to be used as food, penning up the poultry, and placing the pig, naturally an active and intelligent animal, within the confines of a sty. In order that the animal may be compelled by a process of exclusion to devote itself entirely to feeding and to furthering the development of fat, it is rendered asexual by an operation which is in a high degree painful. Nevertheless, these deductions are only minimised in some degree, and it will ever be impossible to get rid of them altogether. It follows, therefore, from what we have said that, at any rate in a thickly populated country, it is an economy to go straight to the vegetable world for food rather than to consume the flesh of animals. The high price of meat is an indication of what has just been alluded to. There is a loss in converting vegetable into animal produce, and the value of the latter rises in proportion to that loss. Life may be very cheaply sustained on vegetable produce, such as bread, oatmeal, peameal, &c. The cost of animal food is two or three times as great in the case of milk, cheese, and butter, and about twelve times as much in the case of beef, veal, ham, &c. According to Frankland, if an average man were to confine himself to one article of diet he would require, to support life from day to day, 5'068 lb. of potatoes; 1'156 lb. of Cheshire cheese; 1'335 lb. of peameal; 1'341 lb. of ground rice; 2'345 lb. of bread; 3'532 lb. of lean beef; 4'300 lb. of lean veal; 6'369 lb. of whiting; 8'745 lb. of white of egg; 2'209 lb. of hard-boiled egg; 9'865 lb. of carrots; 12'020 lb. of cabbage; 6'93 lb. of butter; 555 lb. of beef fat; 6$\backslash frac\{1\}\{2\}$ bottles of stout. It is not, of course, supposed that healthy existence can be maintained on one or two food-stuffs alone; the diet should be varied as well as plentiful, and in order to be economical it must be drawn largely from the vegetable world.

The various countries of the world differ very widely in regard to their power of producing within their own borders food and to spare for all their inhabitants. The United States is the most conspicuous example of a country which raises in superabundance the essential food-stuffs required by its own people, and has of many kinds a large surplus available for export. Few European countries save Russia are self-sufficing in this way. Great Britain is the most notable example of a country which is very largely dependent on foreign countries for the food of its people, and to an ever-increasing extent. At the beginning of the 19th century, according to Mulhall, the grain imports into the United Kingdom did not exceed 4 million bushels annually; in 1851-60 they had risen to 78 millions; in 1871-80, to 229 millions. Mean- while the home production of grain had fallen, being in the decade 1871-80 about 345 million bushels. In the years 1880 to 1888 the imports of wheat alone varied from 90 million to 112 million bushels, while the production in 1888 was only 72 million bushels. The total food imports, including wheat, meat, butter, cheese, sugar, tea, coffee, rice, and eggs, increased from 2271 thousand tons to 5506 thousand. Great Britain imports about 37 per cent. of the meat consumed, 58 per cent. of the cheese and butter, and 61 per cent. of the wheat required. It may be said that Great Britain obtains nearly one-half of its food-supplies from abroad. These food imports are mainly from the United States, Russia, Germany (Denmark); after these, from Canada, India, and Australia. The imports of Indian wheat have greatly increased of late. In 1867 the total value of imports of live animals, meat, butter, cheese, eggs, wheat, flour, grain, hops, sugar, fruits, nuts, and vegetables was £78,611,416, or £2, 11s. 9d. per head of population; in 1883 it was £157,520,797, or £4, 8s. 6d. per head. In 1895 the total wheat production of Great Britain and Ireland was but 38,700 bushels, while the total imports of wheat amounted to close on 160,000,000 bushels.

While Britain has been becoming more dependent on foreign countries, the United States has largely increased its export. In 1821-40 the United States exported on an average 6 million bushels of wheat yearly; in 1851-60, 29 millions; in 1871-80, 147 millions; and since then between 280 and 300 millions. The grain exports from the United States to Great Britain alone in 1883-94 varied from 43 millions of cwts. to 75 millions, with a value of from £20,000,000 to £30,400,000.

A circumstance that has enormously affected the imports from the United States into Britain is the extraordinary reduction in the cost of ocean transit between New York and Liverpool. Thus, while in 1880 each bushel of grain had to pay 9½d. for the transit, in 1886 one penny carried it all the way; and the cost of carrying a ton of flour fell in these years from 25s. to 7s. 6d.

However great be the advantage to Great Britain in having access thus freely to the best markets of the world, there is one aspect of the consequent dependence upon foreign countries which tends to cause misgivings. What could a country depend on for nearly one-half of its food-supplies on foreign countries do in time of a war with a great state, even if it were not one of those on which it was directly dependent? Assuming that the navy could prevent anything in the way of a complete blockade of the shores of Great Britain, still privateers might seriously hinder the access of necessary food: food cargoes might have to be transferred from British to foreign bottoms, and the consequence might be a swift rise to famine prices. The issues of a great war are, of course, incalculable; but it has been pointed out that it would be well for Britain to minimise the disadvantage, in view of such possibilities, by developing as far as possible the food-raising and food-exporting resources of her own colonies, while diligently striving by improved agricultural methods to make every acre at home raise as much more food for man and beast as is possible.

See the articles DIET, DIGESTION, COOKERY, NUTRITION, and the books there quoted, as also the separate articles in this work on ALCOHOL, BEER, BREAD, CHOCOLATE, COCOA, COFFEE, WINE, &c.; for the subject of adulteration of food, see ADULTERATION; and on food generally such works as Pavy, Food and Dietetics (1875); works on Food by Hassall (1876), Blyth (1881), Letheby (1882), Thompson (1886), Bruen (1887), Yeo (1890), Burnet (1891), Roberts (1891), and A. W. Buckland (1893).