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Titles included in this collection are listed in the volumes published by the Cornell University Press in the series The Literature of the Agricultural Sciences, 1991-1996, Wallace C. Olsen, series editor. FOODS THEIR ORIGIN, COMPOSITION, AND MANUFACTURE FOODS THEIR ORIGIN, COMPOSITION AND MANUFACTURE BY WILLIAM TIBBLES LL.D.; M.D. {Hon. Causd) Chicago, L.R.C.P. Edin., M.R.C.S. Eng., L.S.A. Lond. MEDICAL OFFICER OF HEALTH, FELLOW OF THE ROYAL INSTITUTE OF PUBLIC HEALTH, ETC. AUTHOR OF " FOOD AND HYGIENE," " THE THEORY OF IONS," ETC. LONDON BAJ-LLlfeRE, TINDALL AND COX HENRIETTA STREET, COVENT GARDEN 1912 [All rights reserved] PREFACE The literature of the chemistry of foods is ever increasing, but it is scattered throughout many books, journals, magazines, the bulletins of Governmental departments, works on the special branches of food anal37sis, physiological chemistry, and metabolism. In writing the following pages the author had in view the ever- increasing demand for knowledge of this subject by the members of the medical profession, chemists, and others. The chemistry of foods is closely bound up with the chemistry of the living organism ; to apply the former to the science of dietetics, it is necessary to know the chemistry of living tissues ; without a knowledge of the chemistry of the human frame, it is impossible to appreciate the difference in the value of various foods to the body. The author has therefore thought it necessary to give an outline of constructive chemistry based on the theory of ions, and also an outline of the chemistry of constituents of the living organism, or what is commonly called " physiological chemistry." It is believed that a careful study of these two branches of science, especicdly by medical men, is essential to a thorough understanding of the subject of foods and feeding, and without such knowledge the student will fail to grasp the fuller meaning of the science of dietetics. The great importance of dietetics from a national point of view, as well as from the side of medical science, cannot be too often impressed upon the pubhc. Science alone can establish its necessity. The supply of pure food is a means of establishing the health of the people and the betterment of the human race. The constancy of the Government of progressive countries in their attention to this subject is praiseworthy. Philanthropists cannot better forward the cause of humanity than by the study and application of the science. One of the greatest medical journals says : "A more accurate knowledge of the value of foods in heat units would lead vi PREFACE to a greater precision in the directions given for their administration, and to a more reasonable system of dietetic management, whether in health or disease." The heat value of most foods is given herein. But the remarks of that journal apply with equal cogency to a knowledge of the proportions of protein, fat, carbohydrates, and the mineral salts. A consideration of these substances forms the chief bulk of the following pages. The author acknowledges his great indebtedness to the published works of Wiley, the late Professor Atwater and his band of co- workers, Robert Hutchison, Bell, Allen, Thorpe, Konig, and many others whose names are scattered throughout the pages hereof. The journals of chemistry, analysis, phjrsiology, public health, and medicine, have been laid under contribution, besides numerous works on the special departments of food manufacture. To collect the material, bring into line the information from many sources, to draw from opposing parties the pith of their knowledge and apply it to the subject in hand, in order to render the matter as far as possible complete, has been a work of pleasure and source of delight. W. T. Nottingham, April, 1912. CONTENTS PART I CHEMICAL CONSTITUENTS OF ANIUAL AND VEGETABLE FOODS CHAPTER PAGES I. The Chemical Constituents of Animal and Vegetable Foods - - 1-23 II. The Classification and Characters of the Proximate Principles of Foods - - 24-70 PART II UATEBIA ALIUENTABIA FROm THE ANIUAL EINQDOffl III. The Mammalia : Beef ; Mutton ; Venison ; Pork ; Hare, etc. .... 71-84 IV. Meat : General Considerations ; Choice of Meat ; Post-Mortem Changes ; Preservation of Meat ; Diseased Meat - 85-110 V. The Composition of Meat : Organs, Tissues and Joints ; the Digestibility and Absorption of Meat i 11-136 VI. Soup, Beef-Tea, Beef-Juice, Meat Extracts, etc. 137-155 VII. The Aves : The Classification and Particulars of Birds ordinarily consumed ; their Composition and Place in the Diet ; Eggs of Fowls and Other Birds — their Composition, Preservation, etc. ; Egg Sub- stitutes ... 156-182 VIII. The Pisces : Classification of Fresh and Marine ' Fishes ; Fish as Food ; Composition of Many Species. Mollusca, Crustacea, Echinodermata, Reptilia AND BaTRACHIA - r 183-235 IX. Milk : Its Composition ; Legal Limits of Variation ; Testing the Milk ; Milk of Diseased Cows ; Changes produced by Bacteria - 236-271 X. Milk -Preparations ... 272-294 XI. Cheese : Manufacture ; Ripening ; Composition 295-323 XII, Butter and Butter Substitutes 324-352 XIII. Food Oils ... . 353-367 iriii CONTENTS PART III UATEBIA ALIMENTABIA FBOH THE VEGETABLE EIMGDOU CHAPTER PAGES XIV. The Cereai^ : Wheat and Wheat Flour 370-398 XV. Bread : Its History, Manufacture, Varieties, and Composition 399-437 XVI. Breakfast Foods; Infants' and Invalids' Foods 438-450 XVII. Baking-Powders 451-459 XVIII. Rye, Oats, Barley, Rice, Maize, Millet, and their Products 460-489 XIX. Roots and Tubers 490-525 XX. Dried Legumes or Pulses 526-540 XXI. Green Vegetables 541-566 XXII. Fungi ; Lichenes ; Ajlgje 567-588 XXIII. Fruit : Classification and Composition of Varieties 589-661 XXIV. The Preservation of Fruit - - 662-681 XXV. Nuts : Their Composition and Value 682-696 PART IV CONDIMEirrS AKD SPICES XXVI. Sugar, Glucose, Honey, etc. XXVII. Confectionery XXVIII. Vinegar XXIX. Condiments and Spices 697-732 733-746 747-755 756-778 PART V BEVEBAGES XXX. Tea, Coffee, Cocoa, etc. XXXI. Malt Liquors XXXII. Spirits XXXIII. Wines XXXIV. Non-Alcoholic and Low Alcoholic Beverages 779-819 820-850 851-879 880-919 920-935 INDEX - 937-950 FOODS THEIR ORIGIN, MANUFACTURE, AND COMPOSITION PART I CHAPTER I THE CHEMICAL CONSTITUENTS OF ANIMAL AND VEGETABLE FOODS ■"OOD is necessary to all organisms for their development and rowth, to supply them with heat and energy, to make good the jsses resulting from the wear and tear of their mechanism, and to :eep them in a state of efficiency. The elements of all our animal and vegetable foods are derived rom the inorganic earth, air, and water. It is obvious that animals ould not live upon inorganic substances or derive nutriment from (lem, important as such inorganic materials are for many vital rocesses. The essential parts of animal structures are derived rom previously organized materials. Most of these organic com- ounds arise in the vegetable kingdom as comparatively simple ibstances, and become elaborated into more complex bodies in le vegetable or animal organism. Therefore it may be said that le constituents of human food, the elements of the human body, re derived from the denizens of the earth, air, and water. The body of a man weighing 154 pounds consists of the following proximate >nstituents, which are estimated ^ to be in the proportion stated : Composition of the Human Body. Water Albumin, globulin, myosin Calcium phosphate Fat Ossein and collagen Creatin, creatinin, etc, Cartilagen Haemoglobin . . Calcium carbonate Neurin, lecithin, cholesterin, cerebrin Magnesium phosphate Inosite and glycogen . Sodium sulphate, phosphate, and carbonate Potassium sulphate, phosphate,' and chloride Silica Pounds. Ounces . . 109 .. 16 s 8 12 4 8 4 7-8 4 2 I 8 I 8 I 0-8 — 13 — 7 — 3 — 2'2 — 1"7 — O'l ' Bell's " Chemistry of Foods," p. 5. 2 FOODS: ORIGIN, MANUFACTURE. AND COMPOSITION The materials which compose the structures of man's body are derived from his food, and are in turn composed of elementary inorganic substances to which they can be reduced. The most important of these elements are carbon, hydrogen, oxygen, and nitrogen, which form |8 of the entire weight of the body, and enter into the construction of every cell. There are other elements which, even though they form but a small proportion of the weight of the body, are of prime importance to the proper construction of various special parts of the body — e.g., iron for the blood, and phosphorus for the brain and nerves. A few remarks on these elements will not be out of place. Carbon occurs free in Nature as graphite, charcoal, £ind diamond. It forms a very important part of the earth's crust, being a con- stituent of all the natural carbonates, such as limestone, chalk, and dolomite. It also exists on the surface of the earth as the carbon dioxide of the atmosphere. It is the basis of all organized matter, and leads up to life through a variety of combinations with hydrogen, oxygen, and nitrogen. Hydrogen occurs in a free state in very small quantities upon the earth, but it is found chiefly in the form of water. It is also abundant in combination with carbon as methane, sulphur as sulphuretted hydrogen, and chlorine as hydrochloric acid. All known acids and aknost all organic compounds contain it. It is taken up by plants in the form of water and ammonia. Animals, by using the plants as food, appropriate the compwunds containing hydrogen, and assimilate them to their own body. Hydrogen ultimately leaves the body in the form of water and ammonia or such compounds as are speedily reduced to this form. Oxygen occurs free in the atmosphere, and, in combination with other elements, is the most widely distributed of them all. It forms nine-tenths by weight of water £Hid about half the weight of the rocks which form fiie earth's crust. It is the only element which enters the animal organism in a free state. Plants take it up principally in the form of water and carbon dioxide ; out of these they synthetize organic substances, which become the most important foodstuffs of man, and, being consumed by him, are utilized, and returned to the atmosphere in the form of water and carbon dioxide. A balance is thus held between the oxygen and carbonic acid of the atmosphere ; animeds give to the air the CO^ required by plants for synthetic processes, and plants yield the oxygen needed by animak and man for the purposes of oxidation. There is an antagonistic relation between the two gases which is beneficial to the entire organic world. Nitrogen in a free state forms four-fifths of the atmosphere. In combination it is found in ammonia, nitrates, and the nitrogenous constituents of animals and plants. The nitrates and nitrites exist in soils and water. They arise in part from the decomposition of previously-formed organic material, and partly from the action of nitric acid upon inorganic bases. Nitrite of ammonia is, to a small extent, formed in the atmosphere during thunderstorms, by the union of nitrogen with water — 2N + 2HjO = NH4N02. As a general rule, nitrogen can only enter into organic nature in CONSTITUENTS OF ANIMAL AND VEGETABLE FOODS 3 the form of compounds — e.g., ammonia, nitrites, and nitrates. These simple bodies are transformed by plants into proteins. Vegetable proteins are consumed by animals in their vegetable foods, and converted into the animal proteins of the blood and tissues. During the metabolism of the animal body such proteins become reduced to quarternary or ternary compounds of nitrogen, and leave the organism chiefly in the form of urea, creatin, and ammonia. Sulphur occurs in a free state in various parts of the world, but in such a form it is of no use to organic bodies. It exists in the soil in the form of sulphates of the alkalies and alkaline earths. As such it is absorbed by vegetable organisms, which utilize it in the construction of the protein molecule. It is in the form of protein only that animals can utilize sulphur, and, having utilized it for metabolic purposes, excrete it in the form of ethereal sulphates or as a constituent of bile, hair, and nails. The advantage or dis- advantage of the presence of inorganic sulphur in our food is un- known, but of its importance in the organic form there is no shadow of doubt. The amount of sulphur in various constituents of our food is not well known, but Richet* states that it exists in the following proportion in some of them : Sulphur in Dried Proteins. Per Cent. Egg-white .. i-8o Syntonin .. I-80 Albumin of wheat •• 1-55 Albumin of peas . . 0-40 Gluten . . 070 Phosphorus does not occur in a free state, nor could it be used by plants or animals in that form. It is, however, widely dis- tributed in combination with the alkalies and alkaline earths. Calcium phosphate is present in aU fertile soils. The presence of phosphates in the soil is essential to the growth of plants. In this form only is it taken up by plants, whence it passes into the animal kingdom and forms an important portion of the bones, brain, and nerves. There is, however, a difference in the form of the phos- phorus in these tissues. In the bones it exists as phosphate of calcium and other alkaline earths, which enter the body in an inorganic form, and together form 60 per cent, of the substance of the bones. On the other hand, the phosphorus of the important or vital cellular elements consists of nuclein and various phos- phorized fats or lipoids, such as lecithin, cerebrin, and cholesterin, which are constituents of practically every living cell. It enters the animal body in the form of nuclein, lecithin, phospho-camic icid and glycero-phosphoric acid, and also in the proteins of our ti^od ; and it leaves the body as phosphates — that is, in the inorganic nndition in which it originally entered the vegetable kingdom. 1 " Dictionary of Physiology." FOODS : ORIGIN, MANUFACTURE. AND COMPOSITION Organic phosphoras is therefore present in all the cellular elements of our food, and especially in the yolk of egg, sweetbread, fish roe, and the germ of cereals and legimies. The amount of phosphorus in various foods, reckoned as phosphoric acid, is shown in the following tables : PjOj PER Cent, in Fresh Foods.' Animal. Vegetable. Pork . . . . 0'i6o Carrot 0-036 Milk .. . . 0'220 Turnip 0-058 Beef . . . . 0-285 Cabbage 0-089 Eggs.. 0-337 Potato 0-140 White cheese 0-374 Chestnuts 0-200 Mutton . . 0-425 Barley 0-230 Gruyfire cheese I -3 SO Haricot beans . 0-924 P2O5 PER Cent, in Water-free Substance.* Wheat flour .. 0-3S7 Haricot flour 1-077 C^membert cheese . . I -102 Brie cheese . . 1-272 Cabbage . . 1-625 Lean beef 1-894 GruySre cheese 2-475 Yolk of egg . . 2-843 Iron, although one of the most widely distributed elements, occurs in the imcombined state only in .small quantities, and as such is of no use in organic nature. It occurs in the earth in com- bination with oxygen, and is taken up by plants as an inorganic oxide. There are two forms : ferric oxide, which is a weak base, unable to fix carbonic acid ; and ferrous oxide, which is a strong base, and forms neutral salts with all acids. Iron is of extreme v£due as a carrier of oxygen, and especijilly so in organic life. It is concerned in the production of chlorophyll ; without it the plant becomes pale and etiolated. As a part of vegetables it is con- sumed by animals, and utilized in the construction of hsematogens (iron-containing compounds of nucleo-albumin) and haemoglobin (the oxygen-carrier of the blood). Boussingault^ gives the following table showing the percentage of iron in various food materials : Iron in Fresh Substance. Per Cent. Per Cent. Blood of pig . 0-06340 Maize . 0-00360 Blood of ox • 0-03750 Veal . 0-00270 Oats . 0-013 10 Apples . 0-00200 Lentils . . . 0-00830 White fish . . . 0-00150 Haricots . . . 0-00740 Potatoes . . 0-00160 Egg . 0-00570 Milk 0-00180 Beef . 0-00480 Rice . 0-00150 Wheaten bread . . 0-00480 Carrots 0-00090 Spinach . . . 0-00450 Burgundy . . . 0-00190 Cabbage .. . 0-00390 Beer 0-00040 * Girard : Compt. Rend., 1896, cxxii. 1387. 2 Fleurent : Chemical News, 1906, ii. 16. 3 Compt. Rend., 1872, Ixxiv. 1356. CONSTITUENTS OF ANIMAL AND VEGETABLE FOODS Instructive as Boussingault's list may be, it canpot be acceptec without confirmation. The proportion given is considered by som( authorities to be too high. Bunge gives the following order o foods containing iron, the ash of spinach containing most, and mUl least : Spinach, 0-045 ; yoUc of egg, 0-04 ; beef, 0-02 ; apples, 002 lentils, strawberries, white beans, peas, 0-024 ; egg-white, 0-026 wheat, 0-026; potato, milk, 0-003 per cent. Stockmann^ estimates that the average adult diet contains 10 milligrammes of iron pei diem, and I pint of milk contains 2-2 milligrammes of iron. 100 grammes of oatmeal contain 3T milligrammes of iron. 300 grammes of fine bread contain i-S milligrammes of iron. 280 grammes of common bread contain i-i milligrammes of iron. 120 grammes of beefsteak contain 4-7 milligrammes of iron. Amongst animal foods, therefore, there is most iron in beef and yolk of egg, and least in milk. Oatmeal and lentils are, according to Stockmann, the vegetables which contain most iron, but spinach and apples contain a good deal, bread and potatoes some. The food is the chief and only natural source of iron in the animal world. Manganese is a constituent of various foodstuffs ; it occurs in considerable quantity in some plants and in animal tissues ; but its significance is not weU understood. Silicon exists in abundance in the soil, and, in combination with oxygen, is absorbed by plants. The Graminaceae are rich in sili- cates. Animals ingest them with their food ; a small portion is absorbed from the alimentary canal, and appears to be of importance for the growth of hair. Flaorine occurs in small quantities in most animals and vege- tables ; in the former it occurs especially in the bones and teeth. It is taken up by plants from the soil, where it occurs in combina- tion with calcium. Plants are never without it. Whether it is a necessity of animal existence is unknown, but, considering the small amount of iron in animal blood and its importance therein, it is impossible to say that fluorine is unnecessary. A recognizable quantity has been found in cow's milk, yolk of eggs, and brain. Bunge* says : " It is conceivable that milk, although rich in the important substances of nutrition, might yet be useless for the growth of the infant without the necessary trace of fluorine." Iodine is taken up from sea-water by marine plants. These in turn are consumed by fishes and Crustacea, where it forms a com- pound with other substances in the animal organism. It is only present in very small quantity in the ductless glands of the human body. Bourcet^ found that mature plants and fish contain the following amount of iodine : 1 Brit. Med. Jour., 1895, December 14. 2 " Physiological and Pathological Chemistry," p. 24. * Bull. Soc. de Chim. de Paris, (3) xxiii.. No. i. FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION Iodine in Plants : Milligrammes per Kilo. Solanaceae : Leguminosae : Potato o-ooo Beans Tomato 0-070 Kidney beans Egg-plant . . o-oio French beans Cucurbitacese : Green peas . . Gherkin O'OOO Polygonacese : Cucumber . . 0'0I2 Sorrel. . Pumpkin 0-017 Umbellifera : Melon o-o6o Carrot Crucif erae : Parsley Radish o-i8o Chervil Radish (long) o-i6o Cichorieae : Turnip 0-240 Endive Chenopodiaceae : Chicory Beetroot 0-140 Lettuce Spinach 0-021 Iodine I^ Fish : Milligrammes per Kilc Smoked herring 1-7 to 2-0 Periwinkle Mussels ■ 1-9 Carp . . Portuguese oysters • 1-3 Mullet . . Salmon • 1-4 Shrimps Gurnard . 1-2 Herring roe . . Cod (soft) . 1-2 Herring soft roe Roach .. . 1-2 Sardines Bream . . . 1-2 Pike . . Ling . . . 1-2 Whiting Coalfish . 0-9 Mackerel Eel . 0-8 Ray and skate Sole . . . 0-8 Gudgeon 0-140 0-013 0-320 0-084 0-047 O'OOO 0-000 0-140 0-000 o-ooo 0-096 0-75 0-6 0-6 0-7 0-8 0-6 0-6 0-3 0-3 0-3 0-2 0-I2 Arsenic occurs in the earth as orpiment or sulphide of arsenic. It is found in minute traces in animals and vegetables, but it has not until recently been considered essential to their well-being. Gabriel Bertrand,* however, as the result of numerous experiments, arrived at the conclusion that arsenic, instead of being a con- stituent of a few tissues only, is a constant element of the living cell, like carbon, sulphur, and phosphorus. He found arsenic constantly present in the eggs of all fowls, in quantities varying from TTFir to y^g- milligramme per egg, according to the part examined ; two-thirds of the total amount is in the yolk, the remaining third in the white, shell, and lining membrane. Copper occurs in the earth in a metallic form, and enters into the composition of many vegetable and animal tissues. The quantity is always small, and it is unknown whether its presence has any special significance. It appears to be always present in the liver, and is excreted in the urine by the kidneys. The amount found ia vegetables by Galippa and in animal tissues by Lehmann is as follows •} ' Bull, de la Soc. Chim. de Paris, 1904, xxix., No. 15. * Chemical News, 1893, ii- 286. CONSTITUENTS OF ANIMAL AND VEGETABLE FOODS 7 Copper in Vegetable Tissues. I kilo of grain contained 5 to lo milligrammes, flour contained 8 milligrammes, bread contained i to 4 milligrammes, potatoes contained 2 milligrammes, grean beans contained 2-2 milligrammes, beans from Soissons contained 11 milligrammes, lentils contained 6-8 milligrammes, cocoa contained 11 to 29 milligrammes, chocolate contained 5-2 milligrammes. Copper in Animal Tissues. 1 kilo of beef contained i milligramme. human liver contained 3 to 1 5 milligrammes, sheep's liver contained 18 milligrammes, calf's liver contained 48 milligrammes, ox liver contained 5 1 milligrammes, dog's liver contained 10 to 20 milligrammes, cat's liver contained 10 to 20 milligrammes, sheep's kidney contained 3-8 to 8 milligrammes, ox kidney contained 3-8 to 8 milligrammes. Salts of copper are used in the artificial colouring of vegetables, fruit, and sweets. Mayrhofer found from 76 to 151 milligrammes of copper salts in i kilo of preserved fruit, and 25 milligrammes in peas and vegetables. Tschirch found as much as 270 milligrammes of copper salts per kilo in carelessly stained vegetables. Lehmann is of opinion that 25 milligrammes per kilo is quite sufficient to fix the chlorophyll of vegetables, and Tschirch considers the chloro- phyll is thus fixed as a copper phyUocyanate. The regular con- sumption of small quantities of copper with the food appears to be harmless. The proportion of copper in the urine is not increased thereby, as it is retained by the liver. Chlorine does not occur in Nature in an uncombined form, but it is very abundant in the 'form of chlorides of the metals and alka- line earths. The commonest form is chloride of sodium and potas- sium, and as such chlorine enters and leaves the animal body, exercising an influence upon metabolism, but taking no part in the formation of cellular elements. The alkalies and alkaline earths — sodium, potassium, calcium, and magnesium — occur freely as inorganic salts. As such they enter into plants, and are consumed by animals. Though present in vegetable and animal organisms to a considerable extent, only a small amount is combined with organic matter, and that very loosely. But their presence is necessary for keeping in solution the proteins of the blood, milk, and various other secretions. PotaMium and Sodium. — Potassium is necessary for the develop- ment of ceUs, especially those of the blood and muscles. Sodium is required to keep certain proteins in solution, and to make the secretions of a proper composition. It has been shown that when young animals are deprived of potash salts they do not develop muscle properly. Scurvy has been attributed to the absence of 8 FOODS: ORIGIN. MANUFACTURE, AND COMPOSITION potassium salts, and this idea receives support from the beneficial effects of fresh vegetables and fruit upon the course of the disease. Possibly the chief use of potassium in the human organism is that of an acid-carrier ; at any rate, the organic acids combined with it undergo oxidation in the system, becoming transformed into alkaline carbonates, which render the blood and urine alkaline. Potassium salts are chiefly found in vegetable foods, sodium salts in animal foods. This is shown in the following table : Potassium and Sodium in 1,000 Parts of Dried Substance. According to Increa.se of Potassium. K2O. NaaO. According to Increase of Sodium. NaaO. Rice I-O 0-03 Rice 0-03 Bullock's blood . 2-0 19-00 Apples 0-07 Oats, wheat, rye Beans 0-I3 barley 5 to 6 ( 3-1 too-4 Peas . . 0-17 Dog's milk . . S to 6 2 to 3 Rye, oats, wheat, Human milk S to 6 I to 2 barley o-i to 0-4 Apples II-O I-O Potatoes 0-3 to 0-6 Peas 12-0 0-2 Hay . . 0-3 to I "5 Milk of herbivora . 9 to 17 T to 10 Human milk , , 10 to 2-0 Beef 1 9-0 3.0 Dog's milk . 2-0 to 3-0 Beans 2I-0 O-I Milk of herbivora . . i-otoio-o Strawberries 22.0 0-2 Beef . . 3"0 Potatoes . . 20 to 28 C )-3 to 0'6 Bullock's blood . . 19-0 Ratio of S ODIUM a ND Potassium In blood the Na : K : I : 0-07 „ egg-albumin . . ,, 0-70 „ yolk of egg . . ,, I'OO „ milk of camivora ,, 0-8 to 1-6 herbivora . 0-8 to 6-0 women _, I '0 to 4-0 „ beef ,_ 4-0 „ wheat . . ,, I2-0 to 23-0 „ barley ,, I4"0 to 2I-0 „ oats ,, 150 to 2r-o „ rice ,, 24-0 ..rye ,, 9"o to 57-0 „ potatoes ,, 3i"0 to 42-0 .. peas ,, 44"o to 50-0 „ strawberries . . 71-0 „ apples lOO-O „ beans . . ,, II0< ) Sodium enters the human system chiefly as chloride of sodium and as common salt in the form of a condiment. Calcinm and Magnesium are important constituents of food- stuffs, and essential for the growth of young animals. The ordinary foods contain enough lime for animal needs, and even more than is necessary for the adult. One of the chief sources of lime is hard water, but milk contains more lime than, there is in lime-water. CONSTITUENTS OF ANIMAL AND VEGETABLE FOODS 9 According to Bunge, lime-water contains 1-3 grammes per litre, whereas milk contains 1-5 grammes per litre. Eggs come next to milk in the proportion of lime, and a less but still important ainount occurs in cereals, especially rice, spinach, asparagus, and radishes. Magnesium is a less important constituent of foodstuffs, and enters very little into the animal organism. According to Richet,^ most foods contain about the same proportion of magnesium as of calcium ; but milk contains less, meat rather more, and bread has five times as much magnesium as calcium. The elements of the various foodstuffs, however, do not by any means all exist therein in the crude and inorganic condition. Though comparatively few in number, the fifteen or twenty ele- ments found in food enter into almost numberless combinations, with carbon as the centre of attraction to the other elements. Nearly all the combinations or compounds which occur in the food of man are formed primarily in the vegetable kingdom, and mankind consumes the vegetables, or animals which have been nourished by them. Animals therefore are all dependent — ^her- bivora directly, camivora indirectly — upon plant life for the chief elements of their sustenance, viz., proteins, carbohydrates, and fats. It will not, therefore, be out of place to give some idea of the constructive process in the evolution of organic from inorganic matter. Although the whole scheme is not clear to us, and we cannot see what is going on in Nature's laboratory, we may by comparison judge of the unknown from known facts. Carbohydrates form the bulk of all our vegetable foods, whereas proteins predominate in the animal foods, and the fats form a variable proportion in both kinds. These bodies all take their rise from a few simple combinations of ions dissociated by the solar rays from carbon dioxide and water. The equation COj-l-HaO^ CH2O + O2 represents in gross the primary synthetic process which occurs in the leaves of plants. CH^O is methylic aldehyde. Now, a very strong characteristic possessed by all aldehydes is the ten- dency to pol5anerization. A poljmier consisting of two molecules of CHgO linked together is C2H4O2, or glycollic aldehyde ; and so on through the entire group of materials known as "carbohydrates." The credit of having first suggested that organic synthesis was begun in plants by the formation of formaldehyde or methyl- aldehyde from carbonic acid and hydrogen peroxide is due to Baeyer.^ This suggestion, however, was not accepted, because both formaldehyde and hydrogen peroxide are fatal to protoplasm. But the hypothesis has since received confirmation from the experi- ments of other observers, notably Usher, Priiestley, and Euler. The former showed that the chlorophyll of plants is capable of transforming carbon dioxide and water — i.e., true carbonic acid (CH2O3) — ^into formaldehyde and hydrogen peroxide ; that in Nature these substances are utilized while in their nascent condition in 1 " Dictionary of Physiology." * Ber. d. Deutsch. Chem. Ges., 1870, iii. 63. lo FOODS: ORIGIN. MANUFACTURE, AND COMPOSITION synthetic work. They further showed that the vital mechanism of the plant is protected from the injurious action of hydrogen peroxide by a catalase or enzyme, which transforms it into oxygen and water, while the formaldehyde is polymerized and transformed into sugar by the Uving protoplasm.* It is not necessary that the carbonic acid utilized in synthetic processes should be taken directly from the air : it may be derived from the organic ajcids or salts absorbed by the rootlets. Stutzer^ found that tartaric and citric acids, in the form of tartrate and citrate of lime, furnish carbon to pljints which are grown in the air. These acids are oxidized to carbonic acid, which, being assimilated and polymerized, produce carbohydrates. Water-plants derive carbon in the same way from dilute solutions of oxalates. Acetates and succinates also furnish carbon in the same way to plants, but not so efiectively as oxalates and tartrates. Stutzer concluded that tartaric and oxaUc acids, which contain carboxyl, cannot be directly assimilated by plants, but that the alcohol group of tartaric and other acids affords direct nourish- ment to them. Schmoeger^ gives an account of his experiments on carbon assimilation, and considers that oxalates and tartrates only nourish the plants by furnishing carbonic acid. Monosaccharides. — Polymerization and condensation form the keynote of the synthesis which is constanly going on in plants, and producing the organized compounds known as " carbohydrates." Three molecules of methyUc aldehyde linked together form the Trioses (CjHjOj) — e.g., glycerose ; four molecules form the Tetroses (C4Hg04) — e.g., er3^tiu-ose ; five molecules form the Pentoses (CjHiqOj) — e.g., arabinose and xylose ; six molecules form the Hexoses or Glucoses (CgHijOj) — dextrose, levulose, galactose, etc. These are monosaccharides, and technically are aU aldehydes or ketones of polyhydric alcohols. Those formed from aldehydes are called Aldoses — e.g., dextrose ; those formed from ketones are called Ketoses — e.g., levulose ; the difference is shown by their synthetical formulae : Dextrose : CH2(OH).CH(OH).CH(OH).CH(OH).CH(OH).CHO. Levulose : CH2(OH).CH{OH).CH{OH).CH(OH).CO.CH2(OH). The monosaccharides are transformed into the corresponding alcohols by the action of nascent hydrogen — i.e., H ions — dextrose, levulose, galactose, becoming respectively sorbite, mannite, and dulcite. The same sugars may again be derived from the corre- sponding alcohols by oxidation of the latter — that is, by the action upon them of hydroxyl, or OH ions.* As a matter of fact, it is usually stated that the sugars are all derived from the hexatomk alcohol mannite (CJiifi^). Disaccharides. — ^Monosaccharides are condensed in such a manner that two molecules are joined together to form a disaccharide molecule. The two monosaccharide molecules are not the same in all cases, but sometimes of two different kinds. During con- ' Proc. Roy. Soc, 1906, bcxvii. 369, Ixxviii. 318. 2 Ber. der Deulsch. Chetn. Ges., 1876, 1395. ' Ibid., 1877, 753-758. * Hammarsten's " Physiological Chemistry," p. 85. CONSTITUENTS OF ANIMAL AND VEGETABLE FOODS ii densation one molecule loses an atom of hydrogen, and the other an atom of hydroxyl, forming a molecule of water — thus : (CgHiaOe,— H) + (CsHijOe-OH) = C12H22O11 + H2O. Dextrose. Dextrose. Maltose. (CfiHiaOfi-OH) + (CgHiaOs— H) = CiaHgaOu + H2O. Dextrose. Levulose. Cane-sugar. (CeHiaOg-H) + (CgHiaOe— OH) = CiaHaaOu + H^O. Dextrose. Galactose. Lactose. Polysaccharides. — The carbohydrates undergo still further con- densation, examples being found in all plant structures. In this manner the polysaccharides, or Amyloses, are formed — that is, by linking together three or more molecules of the hexoses or glucoses in the sugar-cane fashion. The amyloses therefore must be regarded as anhydrides of the glucoses. Starch is formed in the leaves of plants from sugar. Arthur Meyer thinks that it may also be formed from mannite ;^ and there is no reason for denying this, especially as sugar may be derived from mannite. Starch is stored in many parts of vegetable organisms. When it is wanted for the use of the plant, it is converted into monosaccharides by amylase, an enzyme whose existence in the leaves was discovered by Leon Brasse, and confirmed by Schimper. This hydrolysis of amyloses also occurs under the action of diastase and other enzymes, and dilute acids and alkalies. Still further combinations of the hexoses occur, to form Glucosides, wherein the molecules are joined together in regular ether fashion — that is, one molecule drops an atom of hydrogen, the other hydroxyl, whereby a molecule of water is lost. Hydrocarbons. — Carbon is probably the most plastic of all the elements, and is admitted to be the basis of organized matter and of life. By its combinations with hydrogen it forms the series known as the " hydrocarbons," the simplest member of the series being methane (CH^). It consists of a single atom of carbon, each valency of which is joined to a single atom of hydrogen, thus : H I H— C— H. I ■ H It is believed by some authorities that the whole organic world is constructed out of methane, by repeatedly removing one or more of the atoms of hydrogen and replacing or substituting something else for it. We know, at any rate, that the assimilation of carbon is the characteristic feature of all living bodies. That the existence of an asymmetrical carbon atom is the nucleus around which the other elements congregate in the growth and development of all organisms is also the accepted belief of many scientists. 1 Ceniralb. fiir Agrik. Chem., xv. 7. 12 FOODS: ORIGIN, MANUFACTURE, AND COMPOSITION The asymmetric carbon atom is one which has each of its four valencies saturated by a different element or radical, as in the following examples : CH3 CH3 I I H— C— OH H— C— OH I I COOH CH2.COOH Structural formula of sarcolactic or Structural formula of hydroxy- ethylidene lactic acid (CaHeO,). butyric acid (C^HbO,). Carbon usually presents four valencies, which must be saturated by union with other elements or atoms of carbon. The valency is the power of an atom to combine with other atoms or combinations of atoms. The capacity of carbon for self -saturation or union with other atoms of carbon is truly marvellous. It is probably owing to this capacity that its compounds exist in such endless variety. By its complex combinations with hydrogen, nitrogen, and oxygen, it occupies an important position in the constructive processes which lead up to the vitalization of matter. An element of such remarkable power displays its plasticity in the exhibition of af&nity for various elements. In its combina- tions with hydrogen it may show a greater affinity for some other element ; or some ion which is more strongly charged with electricity has the power of displacing some of the hydrogen and occupjring its place. Thus hydroxyl, or OH ions, are capable of displacing hydrogen from a carbon compoimd or hydrocarbon, because they carry a greater charge of electricity and are electro-negative. Hydroxyl ions may also rob the hydrocarbon of hydrogen, uniting with it to form a molecule of water, and thereby leave the rest of the molecule with one or more free valencies, which demand satis- faction by union with another substance — e.g., CH4-i-OH= H2O-1-CH3, etc. Thus we have CH3, CHjj, and CH, derived from CH4, forming respectively monovalent, divalent, and trivalent ions, as shown by the formulae — I CH2 = H— C— H. Methylene. The question arises as to whether these bodies, the unsaturated compounds of carbon atoms, exist in a free state. They probably do not, except temporarily during a chemical action ; but they are important ions separated or dissociated from more complicated compounds. By reason of their unsatisfied affinities they could not remain free ; when no other element is at hand which will satisfy their demand, they unite together to form the hydrocarbons, and thus we have a series : Methane, CH4 ; methyl, CH3 ; methylene, CHj ; methine, CH Ethane, CaH. = CH3.CH3. Propane, CsHg = CH3.CH2.CH3. Butane, C4H10 ='CH3.CHij.CH2.CH3. Pentane,'C6Hi2 = CHj.CHa.CHo.CH-.CH,. Hexane, CgHi4 =lCH3.CH2.CH2.CH2.CH2.CHs. CaHg + OH clnl + 2OH C3H8 + 3OH '-'4^10 + 4OH CONSTITUENTS OF ANIMAL AND VEGETABLE FOODS 13 Alcohols. — ^An instance of the oxidation of hydrocarbons by hydroxyl ions is seen in the alcohol group ; one hydroxyl ion, by means of its more powerful electrical charge, is able to displace and occupy the position of an atom of hydrogen in the hydrocarbon molecule — thus : H + CaHgO, or C2H5(OH), ethyl alcohol. H2 + C2Hg02, ethylene alcohol or glycol. 3H + CgHgOs, triatomic alcohol or glycerine. 2H2 + C4H10O4, butyl alcohol. CgHj4 + 60H = 3H2 + CgHi406, hexyl alcohol or mannite. Ethers. — In the polymerization of aldehydes, such as was shown under the heading of carbohydrates, two or more molecules become linked together after each has dropped an atom of hydrogen or hydroxyl. This is the usual manner of the formation of ethers from alcohol — that is, one molecule of alcohol loses an atom of hydrogen, the other hydroxyl, and the radicals become linked together in true ether fashion. This mode of the formation of new molecules in living bodies is an important one, much used in cellular processes, and is clearly seen in the construction of fatty and other bodies. Acids. — ^The hydroxyl ion is a very potent provocative of change, and takes an active share in the chemical processes of the cells of plants and animals. It can react upon alcohol, and by dehydro- genizing it or oxidizing it reduce it to an aldehyde or ketone — e.g. : CeHuOs + 2OH = CgHiaOe + zHgO. Mannite. Dextrose. In the same way a primary alcohol — e.g., ethyl alcohol — ^would be reduced to an aldehyde — ethyl aldehyde : C2HgO + 20H = 2H20 + C2H4O. If a secondary alcohol be the subject of its action, the result is a ketone — e.g., secondary propyl alcohol is converted into dimethyl ketone : CjHgO + 2OH = 2H2O + CjHgO. When stiU further acted upon by hydroxyl ions, the aldehydes and ketones are oxidized and transformed into acids. Methyl aldehyde, CH2O + 2OH = HgO + CH2O2 (formic acid). Ethyl aldehyde, C2H40 + 2OH = H2O + C2H4O2 (acetic acid). Propyl aldehyde, CsHgO + 2OH = U^O + CsHgOg (propionic acid). Butyl aldehyde, C4H8O + 2OH = H2O + C4H8O2 (butyric acid). There are monobasic, dibasic acids, etc. Monobasic acids all have only one carboxyl (COOH) in the structure of their molecule. Those formed from the hydrocarbons of the paraffin series are termed fatty acids, because some of the members of the series combine with glycerine to form fat. The foregoing are examples of their derivation from aldehydes. The adjoining table (p. 14) shows the relation of hydrocarbon, alcohol, and fatty acid to each other. Fundamental dibasic acids have two carboxyl groups in their chain, and they are formed from fundamental monobasic acids by the two basic molecules dropping their hydroxyls and becoming 14 FOODS : ORIGIN. MANUFACTURE, AND COMPOSITION ^ tn W K ^ a m -^ O H •w ^J Q < ft- U U ffi H o o O d ■>> U o o 'o Id O CO X to W O 00 U O w o B «i ;S P o tio'O-P C/3 M X "o -_-2'2"2'2 S-- §■3 3.0 01 o a i " "1 * p o'b o x.S H.a.S'S s'c g c o X S <5 13 p >>3 (J-O -Ur I ,^ ^ >!? ^t^ »^ ," ^ »^' P Jh .*^ 1^ CO >-; -s O 00 X m 00 ■^ 2 o o « 14 >.— ^ >. S^ - o o 9 Jo Is ■3 " '>^ W 00-^ iH ^.(jOo J3o 2 o >, — « V u O V B » " o O « s §- 9 !&: sM is « .. B «,- g « 5 B S C « o O « KO!z;Q <4' " S rTLOa ■§-Slu:2- •Htfo'2- WOE-"0>=> o X o •o" 9 O " «? s •r ca •T' o « .a B cS u^io rt J" pJHSftfcS 'Violi -Sis -O «- 3-0 O W O "o •a o O O CO X o I o I- cd X O "> n U W ^- 0-1 I I I I o -r. •3 « -. "O ►« cd a) o U O « « « cd S § §§§s|| CJ CJ O'O^'O Ji J Ji Sis stances. 32 FOODS : ORIGIN, MANUFACTURE. AND COMPOSITION Xanihin, C5H4N4O2 (=2, 6-oxypurin) : It is found in muscle, liver, spleen, pancreas, thjmius, and brain. It is amorphous, or forms granular masses of crystals or thin rhombic plates. It is very insoluble in water, only i part dissolving in 14,000 parts at 16° C; and only i in 1,300 of boiling water. It is readily dissolved by alkaline solutions. Hypoxanthin, or sarkin, C5H4N4O ( = 6-oxypurin) : This sub- stance occurs in the same situations as xanthin, also in bone- marrow, and an extremely small quantity in milk} It occurs in normal urine, but there are considerable quantities in the blood and urine of leukaemic patients. It forms colourless crystalline needles, scarcely soluble at all in cold water, but i part dissolves in 80 of boiling water ; it dissolves in acid or alkaline solutions. Adenine, C5H5N5 ( = 6-amino-purin) : It occurs in aU nucleated cells, especially in tiiymus. It is found in leukaemic urine, and may be obtained in large quantity from tea-leaves.^ It crystallizes in long needles ; is very soluble in warm water, dilute acids, and alkalies ; but cold water only dissolves i in 1,086 parts. It is more soluble in ammonia solution than guanine, but less so than hjT)o- xanthin. GtMnine, C5H5N5O { = 2-amino-6-oxjrpurin), occurs in aU those organs which are rich in cells — e.g., spleen, pancreas, liver, and thymus — ^but only a small amount is obtainable from muscle. It is a colourless and amorphous powder, insoluble in water, alcohol, and ether ; it is easily dissolved by acids and alkalies, but dissolves with difftculty in ammonia. Epiguanine and episarkine are found only in urine. Carnine (C,HgN40g) is a substance found in meat extracts ; it is transformed into hypoxanthin by oxidation. It is a white crystal- line mass, soluble in warm water. The Guanadine Bases — creatin and creatinin — should be men- tioned here. Creatin (C4H9N3O2), or methyl-guanidine-acetic acid, is a deriva- tive of the xanthin or purin bodies, and is found in conjunction with them. It occurs in considerable quantity in the muscles of aU vertebrate animals, but most of all in birds. It crystcillizes in hard colourless monoclinic prisms, and i part is soluble in 74 of water. It is converted into creatinin .(C4H,NjO), the einhydride of creatin. Creatinin is more soluble than creatin, i part being soluble in 11 parts of water, and is more soluble in warm water. It occurs in mamma- lian muscle, the flesh of certain fishes, cind to a slight extent in milk. The guanadine bases are complicated compounds. Gueinadine (CH5N3) is a crystalline substance which may be looked upon as urea (CH4N2O) in which the oxygen has been replaced by an imido-group (NH). On heating creatin with soda, methylamine and ammonia are evolved, Methylamine is important in the synthesis of creatin and sarcosin. 1 Hammarsten's " Physiological Chemistry," p. 135. ' 76 W. PROXIMATE PRINCIPLES OF THE FOODSTUFFS 33 Heteroxanthin {C^^fi^, monomethyl-xanthin (CgHgN^Og), and dime thyl-xan thin, or paraxanthin (C^HgNjOg), are derived from the theobromin, caffein, and theophyllin, which occur in various foods. They form the chief mass of the purin bases of the urine.' Heteroxanthin has a formula identical with that of monomethyl- xanthin, but is said to have a different molecular constitution. Monomethyl-xanthin is the purin body which passes into the urine after feeding with cocoa or coffee {i.e., theobromin or caffein). It forms shining needles, which dissolve with difficulty in cold water, but more readily in solution of ammonia or other alkalies. It does not give the xanthin reaction. Purin Bodies in Food. — ^The quantity of purin bodies in various foods, estimated by Walker Hall, is as follows : The Purin Bodies in F OOD. Food. Per Cent. Grammes per Kilo. Grains per Found. (a) Animal : Pork (neck) •056 •56 3-97 Tripe •057 'i7 4-00 Codfish 058 •58 4-07 Plaice •079 .79 5-56 Mutton •096 •96 6-75 Rabbit •097 •97 6^8i Halibut ■102 I -02 7-14 Beef-ribs •113 1-13 7-96 Ham (fat) •115 i-iS 8^o8 Veal (loin) •116 i-i6 8^I4 Salmon •116 i-i6 8-15 Pork (luin) ■121 I -2 1 8-49 Turkey •126 1^26 8-82 Chicken •129 1-29 9^o6 Beef (sirloin) •130 I -30 9^13 Beefsteak •206 2^o6 14-45 Liver •27s 2-75 19-26 Sweetbread I -006 iO'o6 70-43 (6) Vegetable : Potatoes •002 •02 -14 Onions •009 •09 •66 Asparagus •021 •21 1-50 Peameal . . •039 •39 2^54 Oatmeal . . •053 •53 3^45 Haricot beans •063 •63 4-16 (c) Beverages : Lager-beer •012 •12 1-09 Pale ale •014 •14 1-27 Porter •015 •IS i^3S Practically no purin bodies are contained in milk, butter, cheese, eggs, wheaten bread (white), macaroni, rice, sago, tapioca, cabbage, cauliflower, lettuce, sugar, fruit, sherry, port, volnay, and claret. The Pyrrimidine Bases. — Several bodies known by this name are also derived from nucleic acids ; they are — * Hammarsten's "Physiological Chemistry," p. 135, 34 FOODS: ORIGIN, MANUFACTURE, AND COMPOSITION Uracil, C4H4N2O2 ( = 2, 6-di-oxy-pyrrimidine) : It is derived from thymo-nucleic acid, and from the nucleic acids of spleen, pancreas, yeast, and herring testicles. It forms rosettes of needle-shaped crystals ; readily soluble in hot water, not very soluble in cold water, and almost insoluble in alcohol and ether. Thymin, CsHgNaOj (Srmethyl-uracil) : This results from the splitting of thymo-nucleic acid, and crystallizes in stellar form or dendric leaves. Cystosin, C4H5N3O ( = 6-amino-di-oxy-pyn-imidine) : It is the result of splitting up the nucleic acids of the spleen, pancreas, yeast, etc. It crystallizes in thin leaves which look like mother-of-pearl, and dissolves in water with difficulty. 8. The Derivatives of Protein. — These consist of metaproteins, proteoses, peptones, and polypeptides. These are usually regarded as the products of protein digestion or hydrolysis only ; but seeing that they frequently occur among the constituents of vegetables, it would be impossible to say that some of them are not in course of being transformed into proteins of a higher grade. Metaproteins are the most complex; they consist of acid- albumin and aUcali-albumin, and were formerly called " albumin- ates." But the latter is considered to be an objectionable term, because metaproteins are obtained from both albumins and globulins, and the suffix ate implies a salt. They are insoluble in pure water and neutral solutions containing no salt ; they are soluble in acid or alkaline solutions or weak salines. They are not coagulated by heat ; but, like globulins, they are precipitated by neutral salts — e.g., sodium chloride and magnesium or ammonium sulphate in excess. (a) Acid-albumin, or syntonin, is precipitated from its solution by neutralization even in the presence of alkaline phosphates. (6) Alkali- albumin is also precipitated by neutralization. Alkali-albumin contains less sulphur than acid-albumii).* A very insoluble alkali- albumin (Lieberkuhn's jelly) is formed by adding strong potash to the white of egg. Legumin, or vegetable casein, is simply alkali- albumin formed from native globulins by reagents of the analyst.* Conglatiii is the legimiin from almonds and lupins. Proteoses are less complex than metaproteins ; they include albumoses, globuloses, gelatose, vitellose, caseinose, myosinose, etc., according to their origin. In plants they are called " phyto- albumoses" — e.g., in gluten. They are most commonly proteins which have undergone some chemical change, usually as the result of enzymic action, as in the process of digestion. They give the biuret reaction — i.e., rose-red colour with KHO and CUSO4. They are not coagulated by heat, but most of them are precipitated by saturation with sulphate of ammonia and other neutral salts, also by tannic acid and nitric acid. They are classified as — {a) Proio-proteose or albumose : Soluble in pure water ; precipi- tated from solution by MgSO^, CaS04, and (NH4)gS04. o-Phyto- albumose in wheat flour and papaw juice is a proto-albumose. 1 Ji&ljiburton's "Chemical Physiology," p. 128. * Ibid. PROXIMATE PRINCIPLES OF THE FOODSTUFFS 35 [h) Hetero-proteose or albumose : Differs from the former by being insoluble in pure water, but is soluble in 0'5 to 15 per cent, cold solution of sodium chloride ; precipitated by heat. p-Phyto- albumose in papaw juice is a hetero-albumose. (c) Deutero-proteose or albumose : Differs from both the foregoing in not being precipitated by MgS04. Soluble in hot and cold water. Precipitated by (NHJjSO^. Proto-proteose yields a considerable amount of tyrosin, indol, and a little leucin, but no glycocoll. Hetero-proteose yields abundance of leucin and glycocoll, but only a little tj^osin and indol. Peptones are still less complex than the former groups, and are the result of definite chemical changes usually due to enzymic action. They are hemi-peptone and anti-peptone. They are soluble in water, but are not precipitated by nitric acid, sulphate of ammonia, or other neutral salts. They are, however, precipitated by tannin and an excess of pure alcohol. Although they differ from proteoses, inasmuch as they cannot be salted out from a solution, they resemble those bodies in giving the biuret reaction. Hemi-peptone is split into amino-acids similar to those of the proteoses, and especially leucin and tyrosin, by the action of the pancreatic juice. Anti-peptone is no further reduced. Vegetable peptones occur as the result of the action of enzymes in the plant tissues. Such enzymes are separable from papaw, pine- apple, etc. True peptone, however, does not occur as such in vegetable tissues, but only phyto-alhumoses are formed — e.g., gliadin ; but the vegetable enzymes are capable of producing true peptones from animal proteins. Polypeptides are at present known chiefly as synthetic com- pounds prepared from amino-acids ; some, however, have been separated from the products of protein hydrolysis. The majority of those synthetized do not give the biuret reaction, although some of them do so. Some vegetable proteins are compounds of several. Gluten con- sists of glutin, glu tin-fibrin, gliadin, and mucedin, or vegetable mucin. The presence of gliadin (an albumose) appears to be neces- sary in wheat flour, as well as glutin-fibrin, to make good bread. The flours of barley, rye, and oats, only contain a trace of gliadin, and the seeds of Leguminosae none at all, whence it arises that they are incapable of being made into a light and porous bread. Carbohydrates. In the analysis of foods, the percentage of carbohydrates as stated in ordinary tables represents the total amount of starch, dextrin, gum, sugar, cellulose, fibre, etc. The calculation is very frequently " by difference " ; that is, after estimating the proportion of protein; fat, and ash, the remainder shows the total amount of carbohydrates in the substance analyzed. The determination oi fibre in vegetalile foods, when separately stated, consists of the amount of carbo- 36 FOODS: ORIGIN, MANUFACTURE, AND COMPOSITION hydrate which is not soluble in dilute acids or alkalies. The separation of the total carbohydrates into percentages of starch, dextrin, sugar, etc., requires more careful analysis, and the process is more elaborate when the kinds of sugar have to be stated. The carbohydrates consist of a homologous series of aldehyde or ketone alcohols of the general formula CwHMjOw, and having the following properties in common : (i) A sweet taste ; (2) they are optically active ; (3) they reduce alkaline metallic solutions ; (4) they yield characteristic crystalline compounds with phenyl- hydrazine. Those containing multiples of three carbon atoms are fermentable by yeast, and jdeld alcohol. Individual carbohydrates have special characteristics — e.g., when heated with strong acids they yield characteristic derivatives ; for instance, the pentoses jdeld furfurol, and the hexoses jdeld levulinic acid. They are classified by ToUens^ as monosaccharides, disaccharides, trisac- charides, and polysaccharides, according to the number of Cg groups in the molecule. I. Monosaccharides. This is the grape-sugar group, the glucoses or monoses. They are aldehydes or ketones of the alcohols, formed in various ways. The aldehydes are characterized by their well-known tendency to polymerize. Beginning with simple forms, we have CH^O, or meth- aldehyde, two molecules of which, being linked together, form C2H4O2, or glycollic aldehyde, a syrupy Uquid ; three molecules linked together form CgHgOj, or glycerose, an alcohoUc aldehyde derived from glycerine ; and so on through the series. Triaaes, C3HJO3 — e.g., glycerose. Tetroses, C4H8O4 — e.g., erythrose. Pentoses, C5H10O5 : arabinose, ribose, xylose, and rhamnose Hezoses, C5Hi20g — (o) Aldoses : glucose or dextrose, mannose, galac- tose, fructose, formose, gulose, ^-acrose, talose, rhamno-hexose (CHs.C^HiiOg). Each kind has a dexto -rotatory, levo-rotatory, and an inactive form of sugar. (6) Ketoses : levulose and sorbinose. Heptoses, C7Hj407 : mannoheptose, galaheptose, fructoheptose, gluco- heptose. Octoses, CgHigOg : mannoctose, glucoctose. Nonoses, CgHjgOg : mannonose, glucononose. The monosaccharides are converted into corresponding alcohols by nascent hydrogen, and, conversely, the alcohols are convertible into monosaccharides by the loss of hydrogen. It is the general opinion that all carbohydrates, except inosite, are derived from the hexatomic alcohol mannite — thus : CsHiiOg— H2=CeHiijOe. Mannite. Dextrose. All the sugars named above are known. * "Die Kpblenyhdrate," Breslau, 1888. PROXIMATE PRWCIPLES OP THE POODSTUFPS 37 2. DiSACCHARIDES. This is the cane-sugar group, or saccharoses (CiaHgaOj^), also called sucroses, bioses, or di-hexoses. The chief members of the group are — Saccharose (cane-sugar) . Maltose (malt-sugar). Lactose (milk-sugar). They are condensed glucoses or anhydrides, formed by two molecules of any of the grape-sugar group becoming joined together in ether fashion, with the loss of a molecule of water. They are capable of hydrolytic cleavage into two molecules of the same carbohydrates. 3. Teisaccharides. This is the raffinose group, formed by linking together three molecules of the monosaccharides, with loss of water. The chief representative is raffinose, or melitose, which occurs in manna and beetroot molasses. It is a combination of one molecule each of dextrose, levulose, and galactose, and can be hydrolyzed into the same. 4. Polysaccharides. These consist of more than three molecules of monosaccharides or hexoses, linked together and condensed. They include a great number of very complex substances whose chemical constitution is unknown, but which have the general formula niCgHi^O^). They are most of them amorphous, and devoid of sweet taste. Some are soluble in water ; others swell up, but are changed no further. They are split into monosaccharides or hexoses by hydrolytic cleavage. The principal forms are — (fl) The Starch Group, or Amylases: Starch. Inulin. Glycogen. (6) Vegetable Gums and Mucilages : Dextrin. Gums, (c) The Celluloses. The foregoing classification of carbohydrates is, however, incom- plete, and has been replaced by the following, which was constructed by C. O'Sullivan : Class I. — Saccharans : M(CgHiQ05). These are amorphous carbohydrate substances occurring /'Amylan, a and jS. in growing plants. They are soluble in water, in- I Dextran, o and /S. soluble in alcohol, and jdeld glucoses »(CgHi20g) by -j Galactan, o and /S. the action of acids, without any intermediate I Levulan, o and /S, change. I 7 and 5. 38 FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION Class II. — Saccharens : ^(CsHioOs). Insoluble in water and in alcohol ; they yield "(CiaHg^Oxi) starch, bodies — e.g., maltose, and cane-sugar — under the influ- J jn„iiij_' ence of enzymes or adids, and are finally converted by j Leyuiin, acids into n(CeHi206) bodies. |_Tunicin. Etc. A molecule of starch is supposed to consist of five amylin groups, each con- taining, according to different authorities (CigHjoOxo), or iofCi2^20*^lo). or (Ci2H2oOio)3- Class III. — Saccharins : «(C6Hio05). Amorphous bodies, soluble in water, insoluble in alcohol, tinder the influ- ence of enzymes they are converted into ^(CigHagOii) bodies ; under the influ- ' ence of acids they are first converted into m(Ci2H220ii) and afterwards into «(CgHi20g) bodies. («) Amylo-dextrin (i.) gives a blue colour with iodine. Amylo-dextrin (ii.) gives a red -violet colour with io- Dextrins or dine, amylins. \ Erythro-dextrin gives a red colour with iodine. Achroodextrin, o, /3, y, S, e, t, and ri, give no colour with iodine. Malto-dextrins or/ Compounds of maltose amyloins \ and dextrin. Glycogen. Dextrin-like products from inulin. Class IV. — Saccharons (Sugars). Saccharoses, «(Ci2H220ii). Thej' are sweet and crystalline bodies ; soluble in water and weak alcohol ; converted by acids and enzymes into n (CgHi20g) . (o) Sucrose (cane-sugar), maltose (amylon), lactose. (6) Raffinose (melitose), trehalose (my- cose), melizitose, synanthrose. 2. Glucoses, n[C^Hi " Ceylon," by Sir E, Tenneijt, 8o FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION The Carnivora. As a general rule the flesh of carnivorous animals is tough, coarse, and Ul-flavoured, therefore unsuitable for the food of man. It is only eaten by uncivilized people and by others in great need. But notable exceptions occur among the Plantigrada, which include the bears, badgers, raccoons, etc. The Badger (Meles vulgaris, family Melidce), although classed with the carnivora, only eats small animals and vegetables. The flesh, which is very fat, is eaten as pork, and makes good bacon. It lives in Central Europe, Asia as far as Japan, and America. The American variety is M. Idbradorica, and is also called the " ground- hog." The Baccoon {Procyon lotor) is another plantigrade animal which feeds on small animals and vegetables. There are several species whose flesh is palatable food, inhabiting the American continent from Canada to the tropics. The Aswail, or sloth-bear (Ursus labiatus), is another carnivorous and frugivorous animal whose flesh is highly esteemed for food. It belongs to the family of bears, and inhabits the mountains of India. The Bear supplies food to several nations of Europe, and its hams are considered excellent. The flesh of the brown or black bear is commonly eaten in Norway, Russia, and Poland, where it is salted and dried before being used. It is difficult of digestion. The polar bear was considered by Ross to be unwholesome, but the Esquimaux feed upon it without apparent in- convenience. The Indian tribes of the interior of Oregon also eat bears. The flesh of bears was eaten during the siege of Paris, and W£is considered to have the flavour of pork. Fork. The Hog family [Suidai) are omnivorous. The domestic pigs consist of varieties which have descended from the Wild-Boar (Sus scrofa), which formerly inhabited the forests of Britain, and is still to be found in most parts of the continent of Europe, the greater part of Asia, and the Barbary coast of Africa. Ordmary swine are now bred from the domesticated species in most parts of the civilized world. The breeds most used in Britain, according to Professor James Long,' are— (i) The Large White Pig, whose home is Yorkshire and Lancashire. It reaches an enormous size and great weight. (2) Middle Whites, a cross-breed between the " large " and " small " whites, bred in all parts of the country. {3) Small Whites, a fancy variety, of slow growth. Like the two former, it is of Yorkshire origin. (4) The Large Black Pig, bred chiefly in Cornwall, Devon, and Suffolk, is a pig of great size and weight. (5) The SmaU Black Pig, of Essex, Suffolk, and Dorset. (6) The Berkshire, also of a dead black to a plum colour. (7) The Tam- worth, of a bright sandy colour, usually described as ' ' red." It is of great length, one of the best pigs for the butcher, bred chiefly in the counties of Warwick and Stafford. Porkers do not usually exceed 100 to 120 pounds weight when killed, but bacon pigs attain a great size, increasing in weight at the rate of i or 2 pounds daily. * " The Book of the Pig," James Long, THE MAMMALIA Average Weight of Pigs at Smithfield. Breed. Age. Under 9 Months. 9 to 12 Months. Small White Middle White Large White Large B!ack Berkshire Tamworth lb. 206 287 369 3.34 313 290 lb. 243 372 428 467 414 413 The quality of pork, and especially of bacon, depends very much upon the feeding of the pigs. The Government of New South Wales paid considerable attention to the investigation of this matter, and the following conclusions were arrived at : During the cold season the flesh of pigs becomes " oily," but when the animals are kept warm and comfortable their flesh is firmer and the bacon of better quahty. The bacon is also " soft " when maize forms the principal food. Softness of the flesh also results from the too free use in feeding of oil-seeds, such as rape, linseed, or cottonseed, rice- meal, brewers' grains, and the waste from distilleries. It is recom- mended, therefore, that not more than one- third of the ration should consist of these foods, especially in the last stage of fattening. The too free use of roots, such as mangolds, turnips, potatoes, and green vegetables, causes the production of flesh which is devoid of good keeping qualities. The investigators recommend that the afore- mentioned foods should be used only during the growing stage, if at all, and that they be fattened or " finished off " in the last month or so with foods that will counteract the softness of the flesh, and make it more suitable for curing purposes, and that peameal and skim milk is the best ration for this purpose. Barle3^meal and milk is a favourite ration with many feeders, but the tendency of all grain foods to form soft flesh, according to the authorities quoted, should be counteracted by the addition of peameal. Native species or varieties of pigs having pecuUar forms occur in some countries — e.g., the babyrussa (Sus babyrussa), or homed hog, of the Indian Archipelago and continents of Asia and Africa. The wart-hogs of East and South Africa are also special genera of the Suida, having well-flavoured flesh which is eaten for food. The Peccary (genus Dicotyles) is a native pachydermatous animal of the American continent, nearly related to, and representing, the hog family of the Old World. Several species exist. The tajacu, or collared peccary, (Dicotyles torquatus), is considered good eating in South America, and the white-lipped peccary (D. labiatus) in Paraguay. The Hippopotamus, of which two species inhabit the eastern and central districts of Africa, and a third in Madagascar, may be considered essentially a magnified hog, although they are not true Suidte. The flesh is comparable 6 82 POODS : ORIGIN, MANUFACTURE, AND COMPOSITION to pork, and is eaten with great relish by the natives. When young the flesh is very delicate, but when old it is coarse and strong, and inferior to beef or pork. I The Rhinoceros, of which there are five species in Africa and Asia, is also nearly related to the hog family, and has flesh which is not despised as food. The Rodents : Hares, etc. The family of Rodentia includes numerous animals which are consumed for food and afford excellent sport to man. The Hares belong to the genus Leporiiee. The coramon hare {L. timidus), the Irish hare {£. hibernicus), the Scotch or Alpine hare (L. variabilis), which becomes white in winter, are the British species. About thirty species exist in Europe, Asia, and Africa. In Russia and Siberia some of the species are pure white. Hares are found in nearly all regions from the tropic of Capricorn to the Arctic regions. The common English hare is not indigenous to Ireland or the Highlands of Scotland, where they are replaced by the species mentioned above. The American hare (£. americanus) is littie larger than a rabbit. In South America hares are replaced by cavies. The Babbit (L. cuniculus) is nearly related to the hare, and has almost the same habitat. It is believed that its original home was on the shores of the Mediterranean, whence it spread over Europe at a comparatively recent period after the extermination of its natural enemies. It is not indigenous to Australia, but, having been introduced by man in 1864, it has spread over that continent so as to become a pest. The flesh of the rabbit is white and juicy, loose in texture, without a well-defined flavour, although delicate and easy of digestion. That of the hare is dark and dry in com- parison, and less digestible, and the animal should be hung to improve the flavour and render the flesh more easy of mastication and digestion. The Saninel (family Sciurida). There are the true squirrel {Sciurus), ground-squirrel {Tamias), and flying-squirrel (Pterotnys). The British species (S. vulgaris) feeds upon nuts, acorns, and other seeds, which they stoi« for winter use. Squirrels have a tender flesh which resembles that of the barn- door fowl. It is a favourite dish in Norway and Sweden, iand is eaten by the natives in America, and sometimes by those of England. It is said to make excellent pies, the flesh being dense, gelatinous, but highly agreeable and nutritious. The Marmot, genus Arctomys, family Scturida, is eaten in the Tyrol, Savoy, the Pyrenees, and also in Asia and America. There are several species'. The Alpine marmot is as big as a rabbt. A . monax is the American ground-hog, or woodchuck. The Jerboa (family Dipodida) are little animals of the size of a rat, in Northern Africa, Syria, Siberia, etc. There are several species, but Dipus agypticus is the most common. Its flesh is considered by the Arabs one of the greatest dainties. The alagtaga (D. jaculus) is larger than the common jerboa, and is called by the Arabs the "lamb of the Israelities." Ottier authorities con- sider it the coney of the Scriptures. The Beaver (genus Castor). The common beaver (C. fiber) was formerly common in the North of Europe and America ; it is stul common in America, THE MAMMALIA 83 where it forms colonies. Chiefly valuable for its fur, this animal is much prized as food by the Indian and Canadian hunters, who roast it in the skin after singeing off the hair. The animal is a vegetarian. The Rat, genus Mws, is nearly ubiquitous, although it is not intentionally introduced by man. The brown rat {M. decumanus), commonly called the " Norway rat," was originally a native of China. The black or house rat (M. ratius) was also originally a native of Asia, but spread over Europe some centuries earlier than the former. Where the brown rat is now common the black rat was formerly abundant. Rats and mice (other species of Mus) are considered delicate morsels in Asia, Africa, AustraUa, and New Zealand. To the Chinese and Esquimaux the mouse is a real bonne bottche. The flesh of rats tastes somewhat like that of poultry. They are cooked in various ways. The Bandicoot (M. giganieus) is the largest known rat. It has delicate flesh, resembling pork, which is a favourite article of diet among the natives of India and Ceylon, where they are abundant, and the aborigines of Australia. The Hedgehog, genus Erinaceus, family Erinaceidee, belongs to the order of Insectivorae. They live in Europe (E. europcBus), parts of Africa, Asia, and the Malay Archipelago. There are various species. Their flesh, is sometimes eaten in England, Spain, and Germany. It is considered a princely dish in Barbary. The Porcupine (Hystrix), family Hystricidee, of the natural order Rodentia, was formerly considered a delicacy in Europe, and is mentioned in old cookery-books. It is now occasionally eaten. There are various species in Europe, Africa, and America. Amongst the Edentata, the Armadillo is esteemed good food, roasted in its shell, in Central and Southern America, and the Aard-Vaik, or earth-pig, in South Africa. The Marsupials, including the kangaroo, kangaroo-rat, opossum, and wombat, are eaten in AustraUa and New Guinea, where they are indigenous, and represent the ruminant omnivora of the Old World. Kangaroo (Macropus giganteus) has excellent flesh which eats like venison, and was formerly an important article of food among the natives. Soup made from the tail is far superior to ox-tail soup. It is imported into England preserved in tins. The Wallaby (Halmaturus ualabatus) is eaten in the same way. The Wombat (Phascolomys wombat) has red, coarse flesh, which is fat and resembles pork, and is said to be preferable to that of all other Australian quadrupeds. The Kangaroo-rat, or bettong (Hypsiprywmus), is a separate species, about the size of a hare. It makes highly nourishing and stimulating soup. Although there is an animal called the Opossum in Australia, the true opossum (Didelphys virginiana) only exists in America. Its flesh is said to be pleasant and nutritious. Amongst Oceanic Mammalia, the Porpoise (Phocana communis), genus Cetacea, which lives almost entirely on fish, is welcomed by sailors as fresh food, boiled, roasted, or fried. It was formerly a delicacy in Europe, and is mentioned in old cookery-books. The Greenlamder still esteems it a dainty. Its habitat is the north Atlantic Ocean. The Whale is eaten by the natives " of various countries. Its flesh is said to be tender and palatable as veal, and endeavours have been made to introduce canned whale into the fashion- able restaurants of Europe and America. The flesh is consumed especially upon the shores of Northern Europe, Asia, and America, Western Australia, and New Zealand. The blubber is used as food by the Esquimaux. The Narwhal, or sea-unicom, is eaten in Greenland. The Dogong {Halicore 84 FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION dugong), a. herbivorous mammal of the order Sirenia, and an inhabitant of the Indian Ocean, has flesh which is tender and considered to be not unlike beef. The Walms is eaten by the Esquimaux, and appreciated by Arctic explorers. The Seal is a very important article of food to the Greenlanders and Esquimaux. It is also eaten in Labrador and Kamschatka. Its flesh is coarse and oily. It was formerly served on great occasions at feasts in England. Seals consumed during the siege of Paris were said to taste like lamb. The Uanatee, sea- woman or sea-cow (Manatus of the order Sirenia), which lives on the American and African coasts, is similar to the dugong. Its flesh is whitish, having a flavour between veal and pork, and is said to be excellent eating. CHAPTER IV MEAT : GENERAL CONSIDERATIONS Meat consists of fat and lean, bone and gristle. But the skin, bones, tendon, nerves, etc., of an animal are spoken of collectively as refuse. They are not valueless, but uneatable. Bone, for instance; contains a considerable amount of nutriment, which may be obtained by making soup. These materials, therefore, are only " waste " when they are not converted into food. The total amount varies up to 25 or 30 per cent. Lean meat is practically muscular tissue, but meat is never so lean as to contain no fat. The fat is in various parts of the flesh — in the subcutaneous tissues, between the muscular planes, about the tendons, etc. Besides visible fat, there is always more or less invisible fat present in particles interspersed with the muscular fibres, and apparently indistinguishable from them. First-class meat cannot be obtained from animals that are " poor " in flesh. A reasonable amount of fat must be present to give juiciness and flavour to the meat, and, within reasonable limits, the fatter the animal the better is the meat. The amount of fat in meat varies with the age and condition of the animal. It may be as low as 3 per cent, and invisible, or it. may be as much as 25 per cent, in fat beef or mutton, and from 50 to 90 per cent, in fat pork. The presence of a large amount of fat, however, is not necessary to the wholesomeness of the meat. It is far more important that the animal should be in good health. " Never kill an animal which is losing flesh " is a maxim of importance. When an animal is failing in flesh, the fibres shrink in volume and contain corre- spondingly less water, and the meat is correspondingly drier and tougher. On the other hand, when an animal is gaining flesh the opposite condition obtains, and the meat is of better quality. It is therefore better to kill an animal while in medium flesh, but still gaining, rather than when it is at a standstill or losing flesh. The distribution of the fat is an important guide to the age of the animal. In young animals the fat is interspersed among the muscular fibres, and gives the flesh that marbled appearance which is always a desirable quality of butcher's meat. In old animals the fat is chiefly collected in masses or layers external to the muscles — in the subcutaneous tissues and around the internal organs. In pork the fat is everjnvhere abundant, more or less fatty infiltration or degeneration occurring in the muscular fibres. The abundance 85 86 FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION of fat and the saturation of the muscular fibres by it, even during cooking, is a cause of the relative indigestibility of pork. In con- trariety of this, the flesh of rabbits, chicken, pheasant, etc., contams very little fat ; and this characteristic, together with the shortness of the muscular fibres, renders their flesh more easy of digestion. Although the quality of meat depends so much upon the health and condition or plumpness of the animal, the " breed " must also be taken into account. The best quality of meat cannot be ob- tained from poorly-bred stock. The admixture of fat and lean, or marbling of the meat, " is never got from scrub or native animals, neither do the 'gaudy' feUows, with roUs of fat on their ribs, furnish the ideal quality of meat. There seems to be a connection between the smooth, even, and deeply fleshed animal and nicely marbled meat which is not easily explamed, but the two usually go together. Fine bones, soft luxuriant hair, and mellow flesh, are always desirable in an animal to be used for meat, as they are the indications of small waste and good quality of meat." '■ The age at which animals are killed naturally influences the quahty of the meat, and especially its flavour and texture. The flesh of old animals, however fat it may be, is likely to be more tough than that of young ones. The flesh of young ones, on the other hand, is very watery, and has not attained the flavour natural to the species. For this reason an old animal in good condition affords a better quality of meat than a young one in poor condition or imperfectly developed. A calf should not be killed for veal under six weeks of age, and, when nourished by its mother, is probably best at about ten weeks old. The fat in tLe carcase should then be abundant, white, and brittle. If killed too young, the flesh is not wholesome. It wants firmness, which can only be obtained by the development of muscular fibre. It also lacks those animal juices on which flavour and an important part of the nutri- tive qualities depend. Cattle are fit for beef at eighteen or twenty months old, if properly fed, but even this flesh lacks the flavour of good beef. The best beef is obtained from animals at two and a half to three and a half years old, although the animal may be killed for food at any age if it is in good condition. Small-breed oxen are in their best condition at three years ; large oxen are in their prime at four to five years of age. Cow-beef cannot be eaten too young. Lambs are killed when two to three months old, and any time after. Sheep are usually at their best for providing mutton at about a year old, and in their prime for eating at one and a half to two years of age. Wedder-mutton, the flesh of the castrated animal, is said to be in perfection at three years of age. Ewe-mutton is best eaten young, not more than two years old, but many come into the market at a more advanced age. Pigs are killed at any age after six weeks, and make good pork up to twelve months old. ' Twentieth Report, Bureau of Animal Industry, U.S. Department ol Agriculture, p. 339. MEAT : GENERAL CONSIDERATIONS 87 Choice of Meat. — Mutton is more digestible than beef. When young, well conditioned, and not eaten too soon after killing, its fibres appear to possess that degree of consistence which permits of easy mastication and is most congenial to the stomach. Beef is not quite so easily digested. Its texture is a little firmer, and its muscular fibres longer, but it is equally nutritive. The tender- ness and flavour of meat depend upon the sex, age, breeding, and feeding, of the animal, the length of time since it was killed, and the mode of cooking it. Sex greatly influences the quality of the flesh, that of the female being more delicate and finely grained than that of the entire male — ^ram, bull, or buck — ^which, during the time the sexual organs are functional, may be so coarse and rank as to render it almost uneatable. Castration deprives the meat of this strong flavour, and improves it altogether for edible purposes. Spaying the females also improves the quality of their flesh. In season and out of season are common domestic terms. They imply that at some period of the year the flesh of an animal provides us with a better quality of food than at another. Beef and mutton are never out of season, but they are at their best during early autumn and winter — that is, just after they have been out of doors and had an abundant supply of pasture food, with the advantages of fresh air. Their highest perfection is, therefore, in September and October. Stall feeding, on the other hand, causes the meat to lose its choiceness of flavour, even though the animal gains in fat by eating dry and artificial food. Pork is out of season in summer. Buck venison is at its best from June to the beginning of Sep- tember, when the rutting season begins. Doe venison is in season during winter. Good meat ought to be firm and elastic, the lean being inter- mingled with fat (marbled) in young, healthy, and well-fed animals. The lean should be of a deepish red colour, not dark, greenish, pale, nor soft and flabby. It should have the odour characteristic of meat. The lean of animals killed while in a state of inflammation or fever is dark or otherwise discoloured. It is more moist than usual, and there may be localized areas containing pus or other fluid, and it soon undergoes putrefaction. Meat which has begun to putrefy is soft, pale, flabby, and has an unnatural odour, per- ceptible on a knife pushed deeply into it, and which becomes apparent when the meat is warmed by cooking. When meat is good, the flesh adheres to the bone ; the fat is firm, somewhat yellow, has no red points (blood), is not particularly greasy nor friable to the touch, but is moderately unctuous. When the animal is emaciated, the flesh adheres but slightly to the bone, its fibres are contracted and dry, and the fat is friable and shrunk. When meat is stale or game is too " high," the decomposition has pro- ceeded too far, and bacterial action has taken place, whereby certain poisonous substances of the nature of ptomaines and leuco- raaines are produced. 88 FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION With regard to the choice of beef, it should be pointed out that the qualities of the meat vary with the sex, and are perceptible to an observer. Bnll-beef is very dark red, requires long cooking, is generally dry, tough, and not very agreeable. Oz-beef is the best. It is of a bright red colour, highly nutritious, agreeable to the palate, and digestible. Cow-beef is paler, and not so agreeable to eat nor so good for making beef-tea. Heifer is held in high estima- tion by epicures. The flesh of small-breed animals is always sweeter and better flavoured than that of large ones. The fat of beef should be white or pale yellow. When it is of a decided yellow tint, it indicates that the animal was largely fed on oilcake, cottonseed-cake, etc., and the flesh is not so good for invalids as that fed on roots or pasture. As regards mutton, the smaller the frame and the better the breed of the animal, so much the more delicate will be the flesh ; on the other hand, the larger the sheep and its bones, so, correspond- ingly, the coarser will be the flesh. The difference in the quality of the meat, shown by its flavour and tenderness, depends very largely upon the variety of the animal ; but equally important are the pastures and breeding-ground. Turnips give a flavour to mutton which is distinctly recognizable by the epicure. The peculiar flavour of mountain sheep is easily appreciable. The fragrant herbs belonging to different pastures produce their influence upon the taste of the meat — ^witness the fine flavour of the mutton grown upon the thymy heaths of Sussex. Animals intended for slaughter are made to fast for twenty-four or thirty-six hours before tiieir death. Water is given to them freely; this helps to keep their temperature normal, and washes effete material out of their S3^tem. If they are killed when the system is fuU of food, the meat is too red in colour and has not such good quality. The meat of fasted animals is also believed to keep better than that of animals not fasted. It is obvious that the fasting must not be prolonged sufficiently to produce an unhealthy state of the body. Meat which is known to be the flesh of an unsound animal would naturally be rejected by all persons of refined taste and sensibility, although, as is well known, proper cooking would destroy the disease germs which may be contained in it. Nevertheless, the flesh of animals which have died a natural death, or have been slaughtered during a condition of ill-health, sometimes finds its way into the market and on the table. Lamb and veal are prone to be become tainted more readily than the flesh of mature animals. This arises from the large amount of moisture in the tissues of all young animals, which is a very suitable medium for the development of bacteria. It consists chiefly of lymph and serum, which exudes. from the in- terstices of the tissues when the animal is cut into joints, thereby causing a loss of nutritive material and frying the meat. The object of the cook in sprinkling such joints with flour is to MEAT : GENERAL CONSIDERATIONS 89 prevent that loss, and is partially effective. The freshness of lamb can be told by the dilated pupils and brightness of the cornea, by the muscular rigidity, firmness of the kidneys, etc., which indicate wholesomeness, freshness, and death by the hands of the butcher. If any animal is killed while suffering from fever or any serious derangement of health, its flesh will not be wholesome food. The diseases most affecting cattle are anthrax, black-leg, pneumonia, pleuropneumonia, milk-fever (" drop "), catarrh, influenza, foot and mouth disease ; those most affecting sheep are pneumonia, braxy, liver-fluke (Fasciola hepatica), and other parasites, such as husk (Sirongylus filaria in the respiratory organs) and staggers (CcBfiurus cerebralis, in the nervous system) ; pigs are also affected by swine-fever, pneumonia, measles, husk, and trichinosis. Animals are often killed whUe suffering from actinomycosis, tuberculosis, cholera, swine-fever, and other diseases. There is little evidence of danger arising from the consumption of the flesh of such animals when killed in the early stages of the disease. But it is almost impossible to distinguish the flesh of an animal in the incipient from one in the fully-developed disease. It would be manifestly improper to encourage the consumption of the flesh of any animal in imperfect health. Comment has already been made on the effects of emaciation upon the quality of the meat. It is also known that the flesh of animals who have recovered from a disease before slaughtering does not " cure " well, and possesses bad keeping qualities. " Bruises, fractures, and the like accidents, have the same iU-effect upon the flesh, and, unless the animal be bled and dressed immediately after such accident, it is better not to use the meat for food. This rule should always hold good if there has been a rise of 2° F. or more in the animal's temperature. A rise of temperature before slaughtering is almost sure to lead to stringy, gluey meat, and to create a tendency to souring in curing."' The flavour of meat depends upon various things. It is generally admitted that the flesh of animals which have lived out of doors and roamed about the land in search of their food is of finer flavour than that of stall-fed animals or those confined in enclosed areas. The dark flesh of beef, mutton, venison, hare, and game birds has more flavour than the white flesh of lamb, veal, chicken, pheasant, or rabbit. This flavour depends entirely upon the amount of nitrogenous extractives, or " meat bases " — creatin, creatinin, xanthin, hypoxanthin, etc. The amount of these sub- stances in mutton and pork and the flesh of young animals is comparatively small, and they depend largely upon the fat for their flavour. Thus, Walker Hall showed that pork-neck contained 3-97 grains of " meat bases " per pound ; tripe, 400 ; rabbit, 6-31 ; mutton, 675 ; beef-ribs, 7- 96 ; fat ham, 8- 08 ; veal, 8-14 ; pork- loin, 8- 49 ; turkey, 882 ; chicken, 906 ; beef-sirloin, 916 ; beef- 1 Twentieth Report, Bureau of Animal Industry, U.S. Department of Agriculture, p. 340. 90 FOODS: ORIGIN, MANUFACTURE. AND COMPOSITION steak, 14' 45 ; liver, 19-26 ; and sweetbread, 7000 grains per pound.^ The flesh of mature animals contains more meat bases than that of the yoimg, that of the male more than the female, and that of well-fed more than poorly-fed animals. We have mentioned the influence of the genital organs upon the quality of the flesh. Castration as a rule improves ite flavour ; it also becomes fatter and more tender. Every day the testes are allowed to remain injures the quality, delicacy, and flavour, of the flesh of a male animal. The flesh of a male animal which is not castrated until puberty retains the flavour and coarseness of that of the entire animal. Even the flesh of the female is improved by spas^ng. Birds afford a notable example of the effects of castration in the capon, which retains the tenderness and juiciness of the chicken even at adult age. The flavour of meat is improved by allowing it to hang for some time after being slaughtered. It becomes more tender and softer owing to the action of lactic acid upon the sarcolemma and con- nective tissues, and the flavour is improved by the development of extractives and aromatic bodies. Game is allowed to hang until the changes of decomposition are weU marked, which is necessary for the development of the high flavour so much relished by epicures. The texture or toughness of the flesh depends upon the character of the sarcolemma and the coimnective tissues which bind the muscular fibres into muscle or which surround the muscles. In young and well-nourished animals the sarcolemma is thin and delicate, and the cormective tissue small in quantity; therefore the flesh is tender and easy of mastication. In animals which have arrived at adult age, are poorly nourished, or have been hard-worked, the sarcolemma, connective tissues, and fasciae, become thick and hard ; their flesh therefore is tough, and is not readily softened by roasting nor by long boiling. Post-mortem Changes. — When killed, the flesh of an animal undergoes several changes. The variations in its texture depend upon them. The first stage is the condition of the flesh immediately after it is slaughtered. In young and well-nourished animals it is juicy and quite tender ; in others it is more or less tough. The second stage is the condition of rigor mortis, which succeeds to the former state at periods which vary with the condition of the animsd prior to death, and lasts for a period of from one to seven days. The flesh is stiff, the meat hard and more or less tough. It passes sooner or later into a third stage. Meat is seldom eaten in the first stage in cold climates, except when the need for it is urgent ; but it is usually consumed in the second or beginning of the third stage. As the rigor mortis passes off, the meat loses its toughness and becomes softer and more tender, owing in part to the action of lactic acid upon the sarcolemma and connective tissues, and it acquires additional flavour from the development of aromatic bodies, ' British Medical Journal, 1902, i. 1461, MEAT : GENERAL CONSIDERATIONS 91 The third stage may be divided into an early and a late stage, {a) In the early stage the flesh is edible. This is the period when the flesh softens, becomes tender, juicy, and develops a game flavour, espe- cially in wild animals. It is not quite clear whether this change is due to commencing decomposition or to self-digestion. According to Cossar Ewart, it is due to putrefaction, the rigor mortis con- tinues indefinitely if the entrance of bacteria is prevented, especially in fishes. On the other hand, the rigor mortis often disappears before putrefaction commences ; but it may continue after decom- position is well started (HiU) . According to Halliburton, the change is due to autodigestion. The muscle contains pepsin, and, if it is kept at the ordinary body temperature, the rigidity soon passes away, and proteoses and peptones appear in abundance. In addition to these proteoses and peptones, there arise various amino-acids, diamines or hexon bases, tryptophan (skatol-amino- acid), tyrosin, a little ammonia, and aromatic bodies. So far the changes are those which occur in the development of the game flavour and the softening of the tissues which, in the flesh of animals killed for human food, is considered desirable by connoisseurs. (6) The late stage is undeniably the period of patrefaction. In this stage the proteins are stUl further decomposed, and result in the production of a large number of substances belonging to the aliphatic and aromatic series, which, according to Hammarsten,' are as follows : (i) The aliphatic series, including ammonium salts of the volatile fatty acids, caproic, valerianic, butyric, and succinic acids, with carbon dioxide, methane, hydrogen, hydrogen sulphide, methyl-mercaptan, and other gases. (2) The aromatic and hetero- cyclic products of putrefaction, including phenol, cresol, tyrosin, and aromatic oxy-acids ; phenyl-acetic and phenyl-propionic acids ; indol, skatol, skatol-acetic and skatol-carbonic acids. Curing and Preserving Meat. The preservation of food has been the means of enormously increasing our supply of food from foreign and colonial sources. There are many ways in which meat is preserved, such as by salting, smoking, canning, the use of chemicals, and cold. Beef and mutton are stored in refrigerators and sent long journeys in a frozen con- dition, to be eaten as fresh meat. Beef is also dried. Biltong is dried beef. The meat is cut into thin strips and suspended in the sunshine, by which means it is dried until the substance does not contain enough moisture to support the life of the ordinary putrefactive germs. In consequence these bacteria, as well as the meat, are desiccated, and the meat is no longer a suitable medium for the development of other germs which light upon it. The meat becomes hard, and will keep Indefinitely in a dry atmosphere. It retains most of its nutrient qualities, and is palatable, but not attractive in appearance. It is sometimes smoked as well as dried. This mode of preservation of meat is open to no objection from a sanitary point of view. Biltong also consists of the sun-dried flesh of the deer, koodoo, * " Physiological Chemistry." 92 FOODS : ORIGIN. MANUFACTURE, AND COMPOSITION spring-bok, etc., the prepared article having the appearance of strips of leather. The Boers scrape it with a knife or a nutmeg-grater, and it is Dy no means unpalatable, and is a staple article of food. Halliburton"^ found it has the following composition : Water, I9'4i ; soUds, 8o'59 ; inorganic matters, 6"S9 ; organic, 73'94 ; proteins, 65"86 ; fat, $'14 ; glycogen, 0"I3 ; sugar, 0'09 ; extractives, 2 ■76— per cent. Jerked beef, or the tasajo of Uruguay, is another form of dried meat much used in that country, and exported to the West Indies and Cuba, where it is largely consumed. The slaughtered animal is cut into four quarters, and the bones at once removed from each. After being exposed to the air to cool for about an hour, they are put into strong salt-brine for half an hour. The pieces are then stacked one upon another, with a layer of salt between them, until it has thoroughly penetrated into the flesh. They are then dried by exposure to the air and sun. This is a useful food, especially when fresh meat cannot be obtained. But it is not so nourishing as fresh meat, because it loses half its soluble albumin by the mode of preparation. Other names are applied to dried meat in Brazil and Chili, where dried beef is called charqne, and mutton chalona ; in the Eastern Archipelago it is called dendang, and may consist of pork. The North American Indians call their special pre- paration pemmican (see Meat-Powder). The preservatives most commonly used are — salt, saltpetre, sugar, and molasses. Borax, boracic acid, sulphite of soda, salicylic acid, formalin, etc., are also used ; but, as they are considered by many authorities to be harmful, their use should be avoided. Salt is astringent, and, when applied alone to meat, renders the fibres very dry and hard ; it draws out the meat juices (serum, lymph, globulin, and albumin), and in a few days the fibres contract and harden, so that the volume of the meat is diminished. Salt is not entirely germicidal, but it prevents the development of putrefactive germs and the eggs of various flies and other insects ; moreover, it does not altogether prevent the action of the enz5nnes of the meat. Salt- petre is even more astringent than common salt. Its chief use lies in preserving the natural colour of the meat ; but its use in excessive quantities is injurious to the health of the consumer. Sugar, on the contrary, is not astringent. When used alone, it maintains the original softness of the meat ; when added to a salt pickle, it prevents the hardening and shrinking of the fibres which result from the use of salt and saltpetre, and it manifestly improves the flavour of the meat. Sometimes the meat is preserved by first using vinegar. This liquid can be injected into the arteries and veins before cutting up the meat ; it then permeates rapidly into all the tissues, and acts as a preservative, which is not objectionable if an acid taste is desired. Meat so treated requires less salt in pickling than when this process is not adopted. When meat is smoked, it is first pickled in brine, and a day or two after its removal it is exposed to the smoke arising from the slow combustion of green, hard wood in a smoking-house. This exposure is continued for two or three weeks. The creosote arising from the wood during combustion closes the pores of Ae meat to some extent, thereby excluding air containing bacteria, and is objectionable to insects. Juniper berries and fragrant woods are ' British Medical Journal, 1902, i. 880. MEAT : GENSkAL CONSIDERATIONS 9i sometimes added to the fire to give additional flavour. In the Wiltshire method of curing bacon or hams, a pickling solution is injected all over the fleshy parts of the meat, so that it is at once permeated by the solution. Immediately this is done, a powder consisting of salt, saltpetre, and an antiseptic, is rubbed well into the flesh, which is also thickly sprinkled with it, and laid on a bench for two weeks. By this means it is mild-cured, being after- wards washed and dried. If, however, it is designed to keep it any length of time, the meat is rubbed again with the powder at intervals for another period of seven to fourteen days, after which it is washed and hung up to dry. If it is to be smoked, it is now exposed to the fumes in a smoking-house for a period of three or four days only (see Ham and Bacon). Sausages. — (a) Pork sausages consist of fresh pork in the pro- portion of three parts of lean and one of fat, seasoned with salt, pepper, sage, or other seasoning, and frequently mixed with bread reduced to an even consistency in a machine. This mixture is put into casings consisting of the intestines of hog, sheep, or cattle, which have been properly cleansed, soaked in lime-water or lye, then washed again, and salted or soaked in brine. (6) Bologna sausage consists of beef or beef and fat pork, bacon, or tongue, in the proportion of lo to i, flavoured with pepper, salt, and a little coriander. This is also put into casings, boiled, smoked, and dried. It is said that horse-flesh is sometimes used in the manu- facture of German sausages. The detection of various kinds of flesh used in the manufacture of sausage and other forms of minced meat is a matter of difficulty. The muscular fibres of flesh are much alike. But a skilled microscopist may be able to tell the differences, unless the meat is very fmely minced. Moreover, the fibres of animals of the same species vary as much in size, texture, and coarseness, as fibres of the flesh from different animals. A chemical examination, however, may be of some assistance. Thus it has been ascertained that the presence of more than i per cent, of glycogen is characteristic of horse-flesh. But even this test could not be depended on unless the meat is comparatively fresh, because the glycogen undergoes various changes by which it is transformed into other substances. Further assistance may be gained from an examination of the fat. Fats have a different melting-point, they absorb different proportions of bromine and iodine, and their fatty acids crystallize differently. Saveloy originally consisted of pig's brains, but now is largely formed of pork, pig's cheek, etc., minced with bread or biscuit, and seasoned similarly to sausage. Polonies are usually put into coloured skins ; the interior is similar to sausage. Black paddings are a variety of sausage made of boUed groats and various spices, ihingledjwitii pork, fat, and pig's blood, put into skins and boiled. Pork pies consist of pork cut into small pieces, mingled with spices, and baked in a paste-crust. .1 Ham and Bacon. — ^There are various methods of preserving thenj. 94 FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION (a) Salt-cured Ham and Bacon. — " Home-curing " is done in a simple manner. The sides and legs are put upon a stone slab or table in a cool cellar, and a mixture of salt and saltpetre is rubbed in at frequent intervals, and sprinkled upon them for three or four weeks ; they are afterwards hung up to dry. The modern method^ is as follows : After the animals are slaughtered, the head, feet, and vertebral column, are removed, the sides and legs disconnected, and they are himg up for six to twelve hours. They are then transferred to the " cooling-room," where the atmo- spheric temperature is about 37° F. for twelve hours. In this period the temperature of the meat is reduced to about 40° F., as shown by a meat thermometer. They are then transferred to the " curing-room," where they are injected in numerous places with the following solution, at a pressure of 40 pounds per square inch : Common salt Saltpetre Boric acid Cane-sugar Water .. 55 pounds. S 5 S 20 gallons. The sugar is only added in the winter season. The solution is sterilized by boiling, skimmed to remove rising material^ and allowed to stand in order to deposit refuse. It is injected into the flesh at the same temperature as the atmosphere in the cellar. After injection the sides are piled into stacks, with the skin downwards, and a layer of salt, saltpetre, and boric acid, thickly laid on. They are left for twelve or fourteen days, during which the saline mixture and powder diffuses through the flesh, and they are cured. They are afterwards washed, drained, and trimmed, and are then ready for the market. The hams are chilled and placed in the pickle for twenty-four hours, after which they are pressed to " purge " them of blood, and the saline solution is injected into the principal vein. They are then " salted " in the same way as bacon, for fifteen Aays, and slowly dried in an atmosphere at 80° F. Many hams and bacon are more quickly dried by being hung in a " smoke-chamber " for three days, where the temperature is about 85° F., and the smoke is produced from 0£ik or elm sawdust. The glossy appearance of smokied ham or bacon is sometimes pro- duced by rubbing vaseline into the rind. (6) The Wiltshire Method of producing smoked bacon is as follows : The animals are killed, and at once hung over a furnace for half a minute to bum off the hair. This is a peculiarity of the Wiltshire method, and replaces scalding. They are then decapitated, deverte- brated, the sides and hams cut out, branded, and sent to the " cooling- house," where they are reduced to 40° or 45° F., by the ammonia process of refrigeration. They are afterwards injected with brine, similar to the solution given above, and salted for three weeks. Finally they are transferred to the " smoke-chamber," where they * Douglas, Journal of the Royal Agricultural Society of Great Britain, 1898. MEAT: GENERAL CONSIDERATIONS 95 are hung for three days to dry in smoke derived from ehn saw- dust. (c) The Method of Injection through the Circulatory System. — ^The animals are shot through the brain, and cured by pumping the brine through the heart, arteries, and veins, by great pressure, so that it reaches the smallest capillaries and interstices of the tissues, This method is practised to some extent in Denmark. (d) The Auto-Cure.— This method is also practised in Denmark. The bacon being cut and cooled, brine is injected into the tissues in the ordinary way. The sides are then placed in a large chamber or cylinder capable of holding 200 to 250 sides, and the chamber is closed and the air extracted. By this means a partial vacuum is created, and the interstices of the tissues opened up, so that they are more susceptible to the influence of the brine. After this semi-vacuum has been maintained for one hour, the valves of the chamber are opened, and it is filled with brine and a pressure equivalent to eight 01 ten atmospheres exerted upon the surface of the liquid. The brine is thus driven into all the interstices of the flesh. Finally it is removed from the cylinder, strewn with salt, and placed in a cooling chamber for a few days, after which it is dried. (e) Sugar-Curing. — ^The fresh meat is rubbed over with salt for four days in succession, and left on a stone slab to drain. On the last day some saltpetre is mixed with the salt. During the next fourteen days the meat is rubbed over daily with a mixture of equal parts of sugar and treacle. Finally it is smoke-dried. Or the fresh meat is rubbed with fine sugar, and finally put into a tub containing equal quantities of treacle and sugar, where it is left for several weeks. By this means a protective crust is formed around the meat. Very little moisture is drawn out, and therefore the meat is not so dry as when salt-cured. The crust is removed by washing the meat before cooking it. Ham cured in this way resembles pork in appearance, but has the flavour of ham, although it is sweeter than when cured in the ordinary way. Sugar versus S alt-Cur ing.-^Sa.lt absorbs a portion of the nutritive substance of meat, and extracts some of the nutritive constituents, etc. A solution of salt which has been rubbed into ham or bacon contains albuminoid and extractive matters, phosphoric acid, and salts of potash, more being extracted in proportion to the duration of the application. Sugar is better as a preservative than salt, because it withdraws less moisture, and therefore less albuminoid and extractive matters, and less of the salines. It forms a solid crust around the flesh which protects it, and prevents it drying It does not alter the taste like salt. The chief objections are that it is more expensive, and the sugar requires to be washed off before the meat is cooked. Preservation of Meat by Cold Storage. — ^The packing of salt pork and barrelled beef has been in vogue from time immemorial, but the introduction of modem methods of cold storage and refrigera- 96 FOODS : ORIGIN, MANUFACTURE. AND COMPOSITION tibn has revolutionized the trade. Meat frozen by Harrison's method, introduced in 1873, was a failure, but the invention of the Bell-Colman refrigerating process in Scotland in 1878, and other methods since that date, enable cargoes of meat to be brought from the antipodes none the worse for the voyage through equatorial regions. This enables mariners and passengers to have fresh meat throughout the longest voyage. Perhaps, however, the most im- portant point is that the poorest person is now enabled to buy meat at a reasonable cost. Slaughtering and refrigeration goes on all the year round at the great meat centres, and Europe is supphed constantly with beef, mutton, lamb, rabbits, etc., from Australia and Argentina ; with beef and mutton from America ; hares from Argentina, Russia, and Norway ; salmon from Canada ; poultry and game from various sources. Putrefaction is the result of bacterial activity, whereby changes are wrought in the constitution and composition of the substance. It is, however, a well-known fact that the action of bacteria can be restrained by keeping the substance imder consideration at a temperature below that which is favourable for their development. In tiiis way many foods besides meat — ^namely, fish, eggs, butter, fruit, and vegetables — can be kept fresh for an indefinite period, and the growth of the practice of cold storage has materially increased the world's stock of provisions. The agent primarily used was natural ice. This was followed by the invention of various freezing machines, which, however, proved inadequate, and have given place to more recent methods. It is unnecessary to go fully into details, but an outline of these methods is essential knowledge to the dietist. {a) Refrigeration by Direct Expansion. — In 1845 Gorrie invented a machine for producing refrigeration on the principle that when compressed air, gas, or a volatile liquid, expands, it abstracts heat from the neighbouring substances. When a gas or liquid is com- pressed, it loses its latent heat in proportion to the degree of com- pression. When such a gas or liquid again expands, it acquires heat from the surroundings, and the latter are proportionately cooled. Gorrie used compressed air ; in 1876 Linde of Munich used anhydrous ammonia ; and in 1881 Raydt used carbonic anhydride (COj). The gas is derived from a generator and pumped through a coil of pipes, where it is kept cool by water, to a cylinder where it is compressed under very high pressure. Refrigeration is produced by the subsequent expansion. In direct expansion the gas or air, when liberated, passes into pipes along the walls or ceilings of the cooling-room or refrigerator. Ammonia expands 1,500 times, and absorbs a considerable amount of heat from the surrounding air, thereby producing a very low temperature. The gas passes through the pipes of the refrigerator, and is pumped back into the condenser to be compressed and used again. The compression can be carried to any degree in proportion to the reduction of temperature which is desired, but usually the pressure MEAT : GENERAL CONSIDERATIONS 97 of the condensed gas varies from loo to 200 pounds to the square inch. (b) Refrigeration by Indirect Expansion. — In this method the gas is used to cool a liquid brine in a tank ; the refrigerated brine is afterwards circulated in pipes around the cooling-room, and absorbs heat from the air and contents of the chamber. The circulating brine returns to the tank to be cooled afresh and sent through the pipes again, the current moving at about 60 feet per minute. The gas which cools the brine is also collected and again compressed. (c) Refrigeration by Air Circulation. — Air is cooled by passing it over pipes conveying cold brine, carbonic anhydride, or ammonia. It is then circulated by fans through the cooling or storing rooms, and thus keeps them at a sufficiently low temperature. Such stores can be divided into compartments or chambers, which may be kept at the different temperatures which experience has shown to be desirable for the cold storage of various substances. Chilled or Frozen Meat. — ^The practice is carried out more or less on the Bell-Colman method. After being dressed, the carcases are allowed to hang in a cooling-room, exposed to a current of air for twelve to twenty-four hours. The cold thus penetrates through the substance, and the entire carcase is chilled. Care has to be taken that the action throughout the tissues is uniform, and the tempera- ture reduced stage by stage until the whole substance is chilled or frozen. The object is to preserve the meat, so that when it is defrosted the flesh is sweet and fresh and retains its nutritive qualities. If a carcase be plunged, before the animal heat has disappeared, into a chamber of low temperature — say freezing-point or below it — the external parts are frozen before the internal, and the latter is thus cut off by the frozen zone from receiving the same intensity of cold as the external part. The external frozen zone, contracting on the internal portion, causes many of the cells, whose limiting membranes are stretched to their utmost capacity, to be ruptured, and the cell contents to escape ; and on cutting into carcases so frozen, a pulpy, or even decayed, condition of the meat is found adjacent to the bones. The carcases are therefore first put into a chamber where the temperature is from 37° to 45° F. for fifteen to twenty-four hours. A cold blast is then turned on, or they are transferred to a re- frigerator, where the temperature is gradually reduced to 15° or 17° F. (that is, to 15° or 16° below freezing-point). The carcases require from twenty-four to thirty-six hours to become frozen throughout, sides of beef naturally requiring a longer exposure than sheep, hares, or poultry. They are afterwards transferred to store-rooms, or chambers on the transport vessel, where the temperature is maintained equally low (or even as low as 5° F.) during the voyage. American and Canadian meat sent to Europe is not frozen hard ; it has not to pass through the equatorial regions. Experience has shown that, if kept at a temperature just, above freezing-point, meat, fish, poultry, game, eggs, etc., will keep 7 98 FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION good for a length of time. Enormous quantities of beef are sent annually from huge stockyards and slaughtering centres at Chicago, St. Louis, St. Joseph, Omaha, and Kansas City. On its arrival in Europe, frozen meat is " defrosted " by placing it in a chamber of dry air, where the temperature is allowed to rise gradually. Just as much care is required in defrosting as in re- frigerating the meat, if it is to retain the proper consistence, flavour, and freshness, of meat. When properly treated, meat cannot suffer deterioration ; no rupturing of the cells occurs ; all the properties of the flesh are retained. Neither the proteins nor the fats are chemically affected by the cold. There is no impairment of the nutritive properties when it is thawed, excepting a slight loss of myosin from the cut surfaces. Indeed, when properly frozen, thawed, and cooled, it is much tenderer than meat which has not been so treated. Cold Storage. — ^An enormous quantity of food materials are now kept for an indefinite time in cold storage ; that is to say, they are stored in chambers cooled by air which has passed over pipes con- veying cold brine, carbonic anhydride, or ammonia gas. The circulation of such air is a sufficient protection against the processes of putrefaction by keeping the substance at a temperature below that necessary for the development of putrefactive germs. Ex- perience has shown that the best temperature for the preservation of materials by cold storage is as follows : Brined meat, 35° to 40° F.; fresh beef, 37° to 39° F. ; mutton, 32° to 36° F. ; pork, 30° to 33° F. ; veal, 32° to 36° F. ; ham, 30° to 35° F. ; lard, 34° to 35° F. ; fish, 25° F. ; oysters, 40° F. ; poultry (frozen), 5° to 10° F. ; ditto, cold storage, 29° F. ; fresh fruit, 33° to 40° F. ; vegetables, 33° to 35° F. Rabbits and hares are packed and refrigerated in Australia under Government supervision ; they are chilled in Russia and Norway, and sent from these countries in cold-storage chambers. Careful inspection and carrying out of routine insures that only fresh, sound, and wholesome animals are exported. Canned or Tinned Meat. — The various forms of tinned meat are corned beef, braised beef, mutton, tongue, rabbit, poultry, and game. It is elsewhere explained that the putrefactive changes which occur in meat can be effectually prevented by sterilizing fiie meat, and keeping it hermetically sealed from the air. The products of decomposition of meat include albumoses, amino-acids, ptomaines, hydrogen, carbon dioxide, and marsh gas. The principles of canning therefore include the destruction of the organism which produce these changes, and afterwards hermetically sealing the tins to prevent the access of more bacteria. If the destruction of the micro-organisms is not complete, the bacteria still produce changes in the meat, and the gases accumulate in the tin. When the pressure is great enough, the tin becomes " blown " — i.e., the flat parts bulge — and the contents are unfit for food. Corned Beef. — The meat is cured for several days in a mixture of salt, saltpetre, and sugar, after which it is washed and put into MEAT : GENERAL CONSIDERATIONS 99 a brine of the same materials plus spices. The latter consist of thyme, sage, bay-leaf, coriander, allspice, mace, nutmeg, pepper, etc., in a combination which varies with the maker. The beef is then boiled slowly for one hour, packed into tins, sealed, and steril- ized by boiling or subjection to superheated steam under pressure. Canned Tongue is similarly prepared. The tongues are cured for a few days in salt, saltpetre, and sugar, and dried. They are afterwards soaked in water, then boiled in water containing spices such as the foregoing, put into tins, sealed, and sterilized. They are sterilized either in a retort or a calcium bath, (a) Sterilization in a Retort : The cans are put into a " process kettle " or retort before they are finally sealed down ; the exhaust valve is closed and the cans processed for seventy-five minutes, with steam at 3 pounds pressure ; they are then taken out of the retort, sealed up, and put in again, being now submitted to the action of steam at 4 pounds pressure for one hundred minutes, with the exhaust valve open. Finally they are taken out and rapidly cooled in water. (b) The Calcium Bath : Water containing chloride of calcium can be raised to a much higher temperature than plain water. Advan- tage is taken of this fact in sterilizing canned foods of various kinds. Thus canned tongue is lowered into the bath until the tins are nearly covered. They are then " processed " or boiled at a temperature of 230° F. for forty minutes from the time steam begins to issue from the vents in the tins. They are hermetically sealed before they are removed from the bath, afterwards being transferred to a retort where they are boiled for one hundred minutes by steam at a pressure of 4 pounds per square inch, and finally removed and cooled by immersion in water. Diseased Meat. All slaughter-houses and estabUshments for the sale of meat and its preservation by salting, smoking, drying, canning, or the manu- facture of meat products, should be regularly inspected by of&cials properly qualified to certify the soundness of the material and the sanitary condition under which such foods are prepared, stored, and sold. The entire carcases, parts of carcases or meat, and meat products from cattle, sheep, goats, swine, and horses, which are intended for human food, ought to be inspected by such officers before they are exposed for sale. The establishments in which the animals are slaughtered, the meat cut, prepared, packed, stored, cured, or otherwise handled, should be well lighted, ventilated, and drained. The walls, ceilings, pillars, and partitions, of stables, hovels, pigsties, fasting-pens, should be frequently whitewashed, limewashed, or painted with such material as can be readily washed. Lime- or white-washed walls, etc., should be frequently scraped. Floors and other parts of the buildings which are in a very insanitary condition ought to be replaced. The apparatus of all slaughtering-houses, dressing- loo FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION rooms, canning and packing rooms, should be cleaned every day. The employes should only be allowed to work with clean hands ; they should wear washable aprons and smocks ; there should be lava- tories fitted with hot and cold water for their use ; and the employes should be under the supervision of a foreman responsible for their cleanliness and good health. The rooms in which meat and meat products are stored should have no direct communication with the slaughtering-house, pens, lavatories, etc. The drainage and ventilation should be so arranged that no odours from hides, tanks, manure, or other refuse, can penetrate. Inspection of the Animals — («) Before Slaughtering. — ^AU cattle, sheep, goats, swine, or horses about to be slaughtered for human food, whether for meat or meat products, should be examined in the establishment of the butcher before they are slaughtered. Any animal suspected of being unsound should have an official tag attached, or be so marked upon the ear that it can be easily recognized by some responsible person before removal of the skin or evisceration. If disease of a feverish character be suspected, the exact tempera- ture should be taken, and may reveal such a condition as will lead to its condemnation. It should, of course, be remembered that a rise of temperature may occur from the removal of the animal from place to place, from excitement, etc. Crippled animals should also be marked for further examination. {b) Post-Mortem Examination. — ^Any medical oflftcer of health or inspector of nuisances may. at all times inspect and examine meat exposed for sale or in preparation for sale, and intended for the food of man, and deal with the same under the PubUc Health Act, 1875, sections 116 to 119, and other Acts. All carcases and all viscera should be examined at the time of slaughtering. Carcases and viscera found healthy should be marked as such by the inspector. When any diseased or other condition is ob- served that would render the flesh unfit for human consumption, the carcase or viscera should be marked for further examination. Actually diseased carcases or parts of carcases and organs must then be dealt with as the law directs. All this tends to the necessity for public abattoirs in all large centres of population, as a means of carrying out the work of inspection in a ready and sjrstematic manner. Good meat should have a marbled appearance, due to. streaks of fat between the muscular fasciculi ; the surface should have a bright, florid colour, neither too dark nor too pale. The colour of meat, however, depends on various things : if it is very dark, it is the flesh of an old or diseased animal ; a magenta hue indicates the existence of some acute disease at the time of death. A very pale or yellow colour, sometimes called " white flesh," in an adult animal, is due to fatty infiltration or degeneration or fibroid infiltration. The flesh of all young animals is paler than that of older ones. The colour of mutton, pork, and veal, is paler than that of beef, but this is exaggerated by the fact that sheep, pigs, MEAT: GENERAL CONSIDERATIONS loi and calves, are well bled at the time of killing. On cutting into the meat, it should show a uniform colour, although the interior is a little paler than the exterior. The muscular fasciculi should not be too large ; the connective tissue should glisten ; and it should have the peculiar odour of meat known to all. Any departure from the normal odour should excite suspicion at once. To test this more particularly, a clean knife should be plunged deeply into it, in the direction of the bone, and the knife should be smelt, or some of the meat may be finely minced and mixed with water. The touch of meat should be firm and slightly elastic, which implies freshness and a due rigor mortis. The surface should not be absolutely dry, but should give a slight moisture to the finger when passed over it. This moisture or meat juice should be of a clear red colour and acid reaction. The fai of meat has a firm, greasy feel, and a pale yeUow colour which deepens with age, and becomes distinctly yeUow when the animal has been fed on oil- cakes. There should be no hcemorrhagic points. According to Gamgee, some butchers rub melted fat over the surface of diseased meat, to give it the glossy appearance which sound meat shows. The lymphatic glands should be firm, slightly moist, and of a pale yellowish-grey appearance on section. The marrow should be light red. That of the hind-quarters should set firmly in twenty- four hours, but in the fore-quarters it requires a longer period. The ash of meat should be alkaline. It consists almost entirely of phosphates and chlorides. The moisture : Meat dried over a water-bath should not lose more than 74 per cent, of its weight, the loss representing the amount of water in its composition. On cooking meat, the loss of weight should not exceed 30 per cent., nor its fibres become hard, and it should give off a savoury odour. Unsound meat may lose 40 per cent, of its weight on cooking, and the odour may be unsavoury. If the meat is putrefied, the flesh softens and tears readily ; it loses its elasticity ; some parts become softer than others ; it becomes paler ; the marrow turns brown and softens, and later on the flesh becomes greenish ; the juice has an alkaline reaction, and the odour is characteristic of putrefaction. Diseased meat is frequently of a dark or purple colour, which shows that the animal has not been killed or properly bled, but died with the blood in it, probably of Some febrile complaint, or from some mechanical obstruction to the respiration. Well-defined dark-coloured areas full of blood are either due to hypostatic congestion or post-mortem staining. A yellowish or mahogany colour is due to staining with bile. The animal may be emaciated, as shown by a disproportion between the fat and lean. The meat juice may be dark or otherwise discoloured, and alkaline. There may be tumours or pus between muscular fibres. The flesh may be soft, sodden, flabby, or dropsical. The fat may be soft, flabby, or gelatinous ; or the marrow of bones sets badly. The odour may indicate putrefaction ; a sweet odour will indicate uraemia, a urinous odour suggests extra Vcisation of urine. Other odours may I02 FOODS : ORIGIN, MANUFACTURE. AND COMPOSITION indicate that the carcase has been hung near to odoriferous sub- stances — e.g., tar or carbohc acid — or that some drug, such as turpentine, camphor, or creosote, was administered to the animal, or that it fed on odoriferous plants, such as garlic. The organs may show signs of some special disease. The lungs and -pleura may show signs of hepatization, oedema, suppuration, cavities, nodules, or adhesion, in tuberculosis, pleuro-pneumonia, pneumo-ienteritis, anthrax, and actinomycosis. The thoracic l5miphatic glands may be enlarged, caseous, or purulent. Tuber- culosis is often called the " grapes " or " pearl disease " by farmers, because the tubercular deposits may hang from the surface of the lungs like grapes. The liver may exhibit hydatids, liver-fluke, abscesses, or tubercle ; it may be enlarged, softened, hyperaemic, or bile-stained, in tubercle, anthrax, etc. The spleen may be enlarged, with rounded edges, and show nodules or ulcers, in tubercle, anthrax, parasitic infections, etc. The kidneys may be h3^raemic or inflamed in tubercle, swine-fever, etc. The abdominal lymphatic glands may be inflamed or enlarged in tuberculosis, glanders, pneumo-enteritis (pig- typhoid), swine-fever, or plague, small-pox of sheep, etc. The sUymach and intestines and peritoneum may be hyperaemic, inflamed, or ulcerated, in swine - plague, cattle- plague, anthrax. The existence of such hyperaemia may be due to poisoning by tartar emetic, Rhus toxicodendron, bryony, meadow- saffron. In any case of suspected poisoning by these things, or by arsenic, antimony, strychnine, etc., a piece of meat should be given to a cat or dog. The skin of the animal may show papules or pustules ; the udder may show blisters, ulcers, or nodules, in foot and mouth disease. The head may be enlarged and inflamed ; there may be blisters and ulcers on the tongue and mouth in foot and mouth disease ; swellings under lower jaw in actinomycosis ; the nose may be ulcerated in glanders, farcy, and smallpox ; the brain may show tuberculosis and parasites. Condemned Heat. — ^All animals suffering from anthrax, blackleg, pyaemia, septicaemia, tetanus, rabies, malignant epizootic catarrh, should be condemned without reserve. Actinomycosis, or " lumpy jaw " : {a) When the carcase is well nourished, and the disease has not spread beyond the mouth or tongue, it is considered to be sufficient to condemn the heaid ; the rest of the carcase may be eaten. (6) But when the disease has spread beyond the primary infection of the tongue or mouth, the carcase should receive the same consideration as in tuberculosis. Tabercalosis : (a) All carcases which show marked emaciation should be condemned. (J) But when the signs of the disease are slight, or the lesions are calcified or encapsuled, the carcase is not usually condemned in ioto, but the diseased organs or glands and surrounding parts only, (c) Carcases in which the cervical glands and one organ and serous membrane of one cavity are affected should be condemned as unfit for human food — e.g., cervical glands and one lung and pleura, or the liver, peritoneum, and glands ; excepting that, after removing MEAT. GENERAL CONSIDERATIONS 103 the diseased parts, the carcase may be rendered for the manufacture of lard or stearin by cooking it with steam at a temperature of 220° F. for not less than four hours, (d) When the disease is limited to the superficial lymphatic glands {caseous lymphadenitis), or a few nodules upon one organ and adjacent glands in an animal which is otherwise well nourished, the meat is usually passed after removal of those parts. Swine fever and hog-cholera : (a) If the signs of fever or cholera are slight, being confined to the lymphatic glands and kidneys, the carcases are as a rule passed ; (b) where there are well-marked signs in more than two organs — skin, bones, kidneys, and lymphatic glands — it is usual to condemn the whole carcase, (c) If the lesions are more severe than in the first, but less so than in the second case, the carcase may be rendered into lard or stearin, provided it is cooked in steam of a temperature of not less than 320° F. for four hours. Pneumonia, pleurisy, enteritis, etc. : When the carcase shows marked signs of acute or chronic disease in the lungs, pleura, peritoneum, intestines, or uterus, it is usually con- demned. Fluke, abscesses, bruises, etc. : The particular organ or part of the animal affected by liver-flukes, abscesses, suppurating sores, tumours, or malignant tumours, should be condemned. If the lesions are extensive, the entire carcase should be condemned. Emaciation and anaemia : The carcases of emaciated or very anaemic animals, and those which show a slimy degeneration of the fat or serous infiltration into the muscles, are unfit for human food, and should be condemned. Tapeworm cysts : Carcases affected slightly with tapeworm cysts may be rendered into lard or stearin. If the cysts are numerous, the body should be con- demned. Skin affections : If only slightly affected by mange, scab, urticaria, tinea tonsurans, erythema, etc., the carcase may be passed if it is otherwise sound. The skin of swine afflicted with skin diseases should be condemned. Icterus: Carcases showing an intense yellow or yellowish discoloration after cooling should be condemned. If the yellowish tint disappears on cooling the carcase, it may generally be passed, providing it is otherwise in good con- dition. Carcases afflicted with parasitic ictero-haematuria should be condemned. Those having a strong sexual or urinous odour should be condemned. Immaturity : The carcases of calves, pigs, kids, or lambs, under three weeks of age should be condemned ; and all stillborn or unborn animals should also be condemned as unfit for human food. Pregnancy and parturition: Animals in an advanced stage of pregnancy, and animals delivered within the previous ten days, are unfit for human food — they should be condemned ; but the carcase may be rendered into lard or stearin. Dead or dying animals ." AU animals that die a natural death or are in a dying condition when slaughtered are unfit for human food. A few other notes may usefully be added upon some of these diseases. The common fluke in the liver of sheep and cattle is Fasciola hepaitca, one of the Trematoda. It resembles a sole in shape, is I to i^ inches long and J inch wide, and infests the bile-ducts. I04 FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION Tapeworms belong to the Cestoda. The beef tapeworm (TcBtiia mediocanellata) occurs in beef and veal, where the larvae {cysticerci) are found in the voluntary and involuntary muscles. They are destroyed by a temperature of 135° to 140° F. (60° C.) for a few minutes ; therefore, thoroughly cooking the meat is a sure preventa- tive against them. Human beings are usually infected by eating raw or underdone meat, sausages, etc. Mutton is not so often measly as beef or pork ; indeed, the existence of cysticerci is denied by some authorities, but Cobbold says there is a small tapeworm, which he named Tcenia tenella, and that he has seen the cysticerci in both sheep and lambs. The pork tapeworm (Tcenia solium), formerly considered the common tapeworm, is not nearly so common as that of beef. The cysticerci are small, round, or oval cysts ^V to I inch in size, situated in spaces between muscular fasciculi. Human beings are usually infected from eating raw or underdone pork or sausages, also from salads, raw vegetables, fallen fruit, etc. It is destroyed easily by thoroughly cooking the meat or vegetables. Bothriocephalus laius is indigenous to Ireland, and not common in England. It particularly infests fresh-water fish, such as trout and bleak, and human beings become infested by eating underdone fish. A similar worm infests the dog, but Cobbold considers there is very little relation between the two. On the other hand, the common hydatid {Echinococcus hominis) is commonly obtained from dogs, being the larval stage of the tapeworm Tcenia echinococcus. Sheep, oxen, and man, become affected by asso- ciation with the dog, and by partaking of food and filthy water upon which the eggs abound. They occur in the lungs, liver, brain, and elsewhere. Trichina spiralis is common in pork, ham, bacon, and sausages. It is the juvenile state of the little round worm Trichina, one of the Nematode worms. As commonly observed, the young Trichinae appear as spirally coiled worms in the interior of small, globular, or lemon-shaped cysts, looking like minute specks, which are about ^ inch in length and ^Jg^ inch in breadth. They resemble little specks or particles of lime," and give a more or less gritty feeling to the flesh, according to the degree of calcareous degeneration they have undergone. The adults occupy small lemon-shaped cysts of about the size of a pin's head, the male worm being y^, inch, the female ^ inch, long. They are very numerous in measly pork. One ounce of ham may contain 100,000, and I pound about 400,000,000, parasites. As they migrate from the alimentary canal of the host, they reach first of all the liver, then the diaphragm, intercostal and abdominal muscles. Psorospennue, or Rainey's capsules, which closely resemble Trichinae in appearance and size, are small, oval, or elliptical bodies, formed by small hair-like fibres enclosing granular cells, and are embedded in the sarcolemma, whereas the Trichinae are between the muscles fibres — i.e., outside the sarcolemma. These bodies are obscure in their nature and origin, and may exist in the flesh of most animals consumed, and apparently do no harm to human beings. MEAT : GENERAL CONSIDERATIONS 105 Onchocerciasis. — ^Australian beef frequently presents superfjcial nodules on the forequarters due to the presence of Onchocerca or filaria-like ento2oa. Although they are chiefly on the surface of the brisket and flanks, they are sometimes present in the inter- muscular fat, even when there are none on the surface. They do not appear to be of clinical importance ; and it has been suggested that, apart from the unsightliness of the meat, the parasitic nodules do not render the flesh unfit for food. It is possible, however, that the meat may be deteriorated by the production of a toxin by the parasite, of which there is at present no scientific evidence. Anthrax. — In acute cases the disease runs a rapidly fatal course, the animal dying in one or two days, or even quite suddenly, as if struck with apoplexy. In less acute cases it is fatal in three to seven days. If it ends in recovery, it is hardly likely that the flesh would be used at once for human food. The bodies of animals which have died from anthrax lose their rigidity ; if rigor mortis appears at all, it passes away quickly. The flesh is therefore soft and flabby, and decomposition speedily sets in. Various swellings occur, as oedemas or carbuncles. The oedemas are flattened doughy swellings in the subcutaneous fat, and gradually pass into the healthy tissues. The carbuncles are much firmer swellings. The best mode of diagnosis is that of examining the blood and tissues for the B. anthracis. Anthrax is transmissible to man, but the largest percentage of inocula- tions occur during slaughtering, dressing, or slf?"iing the affected animals, in which case a malignant pustule appears on ne skin. Human beings are also subject to anthrax affecting the lungs or digestive organs, but such cases are rare. In the former case, the workman who dresses the wool, hide, etc.. is most likely to be infected by inhaling the spores. It is then called the " wool-sorter's disease." When it affects the digestive organs, the infection arises through eating the flesh of a diseased animal wluch has not been thoroughly cooked. Both cases are, however, comparatively uncommon, but more fatal than when the disease affects the skin. Blackleg, formerly considered to be identical with anthrax, is a rapidly fatal disease of young animals from six months to two years of age ; it affects young cattle, sheep, and goats, but man appears to be immune. It would not, however, be proper to eat the flesh of animals affected by it. This disease is due to a distinct bacillus, which causes a characteristic tumour or swelling upon the neck, breast, shoulder, or rump. It causes a temperature which ranges up to 107° F., and the animal usually succumbs in a few days. Actinomycosis is commonly known as " lumpy jaw," " big jaw," " wooden tongue," etc. It is a chronic disease, characterized by the formation of peculiar tumours in various parts of the body, more particularly the head, and is due to a fungus, Actinomyces. This fungus appears in the tissues in the form of rosettes — hence the name " ray fungus." The disease is not transmissible directly from animal to animal, but is conveyed into the tissues by various food- stuffs, and gets entrance through slight wounds or abrasions of the io6 FOODS: ORIGIN, MANUFACTURE, AND COMPOSITION mucous membrane of the mouth, decayed teeth, or the shedding of the deciduous teeth. The fungus grows naturally upon vegetables, such as grasses, the ears of barley, wheat, and other grain. Quantities of the fungi have been obtained from between the vegetable fibres of barley which had become embedded in the gums or tongue of cattle. Having penetrated into the tissues, the fungus gives rise to various tumours or abscesses, in which the fungi are visible as pale yellow or sulphur-coloured bodies, about 0'5 millimetre, or -jV inch, in size, which consists of club-shaped bodies radiating from the centre like a rosette. The seat of preference appears to be the tongue, bones of the jaw, parotid gland, and region of the throat ; later on it may cause extensive disease in the lungs, liver, spleen, muscular tissues, and brain. Whether an animal affected with actinomycosis should be used for human food after removal of the diseased organs depends on several things, including the carefulness of inspection, the extent of the disease, and the general condition of the carcase. If the tumours are small and the disease is not general- ized, it is usually considered that if the affected parts are removed the remainder may be used for food. But when the disease is sufficiently developed to cause large swellings and abscesses which discharge into the alimentary canal, and the general health of the animal is afEected^ the carcase should be- condemned, as the flesh is not fit for human food. The carcase should also be destroyed when the lungs or internal lymphatic glands are affected, or when a large number of foci are scattered throughout the body. The vitality of the fungus is very low when exposed to heat, and there is no clear evidence that the flesh can communicate the disease to man. Tuberculosis. — The close relationship between human and animal tuberculosis, combined with the extraordinarily high mortality of human beings when affected by the disease, has raised the question in all civilized countries as to how far animal, and especially bovine, tuberculosis is responsible for the spread of the disease among human beings. The medical and veterinary professions have prose- cuted this subject with ardent zeal, and much knowledge has been gained. If the disease is transmitted from animals to man, how does the transmission take place ? Comparatively few people come into contact with tuberculous cattle ; it must therefore be through meat, milk, butter, or cheese, that the virus enters the body — that is, it is a food disease. It hence becomes a question as to whether all flesh from tubercu- lous animals is unfit for human food. It has been argued that, if it can be shown that the muscles and bones are free from the disease, there is no reason why the meat should not be exposed for sale. Two questions may therefore be asked : (i) How often does the disease affect such parts as are used for food? (2) When the disease is only apparent in the internal organs, do the bacilli circulate in the blood and lymph, and can they be detected in the muscles ? Tubercular disejise of the bones is not unknown, but it is rare. According to Walley, the disease sometimes affects the spongy MEAT: GENERAL CONSIDERATIONS lo; bones of the head, the vertebrae, and heads of long bones, and the synovial membrane of the joints is sometimes dotted with tubercular deposit. Respecting the muscular tissues, it may be said that tubercular deposits therein are exceedingly rare ; but the lymphatic glands in and near to the muscles are often diseased. Whether tubercle bacilli occur in the fluids of the muscular tissue, independently of tubercular deposits, is a matter which can be settled experimentally in any particular case. Such experiments have shown that only in rare cases do the muscular tissues of tuberculous cattle contain B. tuberculosis, and then only in small numbers. Opinions therefore differ about the consumption of the flfesh. Some authorities consider that all the flesh of tuberculous animals is unfit for food ; others hold a contrary view. In Germany, the flesh of animals in which the disease is just beginning, or in which it is restricted to one or more related organs, is not con- demned ; but when the disease has affected the bones, muscles, or glands situated upon or between them, the carcase is condemned as unfit for human food. In cases of generalized tuberculosis — that is, when the bacilli have been distributed by the blood throughout the organs — ^the muscular tissues are liable to be infected, and the carcase is then rejected by all authorities. A discussion arose a few years ago as to the identity of bovine and human tuberculosis, and whether the tuberculosis of animals can be transmitted to man and vice versa. Many experimenters worked to ascertain their identity or otherwise. Experiments on animals with the products of human tuberculosis have often failed to produce any marked disease in animals. Theobald Smith (1898) noticed certain morphological and cultural differences in the bacilli from man and animals, and obtained two types of bacilli from the mesenteric glands of children, one of which was the bovine bacillus. He, however, did not conclude that bovine tubercle baciUi could not produce the disease in man, but he said : " It seems to me that, accepting the clinical evidence, bovine tuberculosis may be transmitted to children when the body is overpowered by large numbers of bacilli, as in udder tuberculosis, or when unknown favourable conditions exist." Koch, however, went far beyond this. In his address on Tuberculosis at the British Congress (1906), he stated that he did not believe that bovine tuberculosis was transmissible to man. He maintained " human tuberculosis differs from bovine tuberculosis, and cannot be transmitted to cattle." As to the susceptibility of man to bovine tuberculosis, he said it had not been settled, but " one was at liberty to say that, if such a susceptibility really exists, the infection of human beings is but a very rare occurrence," and " I should estimate the extent of infection by the milk and flesh of tubercular cattle, and the butter made of their milk, is hardly greater than that of hereditary trans- mission, and I therefore do not deem it advisable to take any measures against it." This conclusion was so radically different from that of other observers that it at once roused great opposition , :o8 FOODS : ORIGIN, MANUFACTURE, AND COMPOSITION and led to numerous investigations in most civilized countries. Koch's conclusions were based on his failure to produce tuberculosis in cattle by inoculating them with tubercular matter of human origin, and his success in causing progressive and fatal tuberculosis in the same animal when inoculated with tubercular material of bovine origin. The generally accepted view now is that human tuberculosis may be, and is, caused by bacilli of either bovine or human origin. Kossel in 1905 recorded finding bacilli of the bovine type six times out of fifty-six cases of tuberculosis in human beings. Ravenel in the same year pointed out that the bovine bacilli had a much greater virulence than human bacilli, and said it would be remarkable, seeing how susceptible man is to tuberculosis, if he were immune to the more powerful virus. Von Behring, in his Cassel Lecture, said he beheved the chief source of human tuberculosis was the contraction of bovine tuberculosis in infancy through feeding on milk; that such tuberculosis often remained latent, and restarted in adult life. The Royal Commission, in its Second Interim Report, 1907, found that thirteen out of twenty- seven cases of tuberculosis in human beings observed by them were of bovine origin. The conclusion from these and other observations is that from 5 to 10 per cent, of the human mortality from tubercu- losis in this country is due to infection from bovine sources. In the Final Report of the Royal Commission on Tuberculosis (1911), it is shown that although the two types of baciUi found in human and bovine tuberculosis present differences, and although certain animals are immune from attacks of the bovine type of the bacillus, man is not one of those animals ; in fact, man is notably susceptible to bovine tuberculosis ; and whether there are two kinds of tuberculosis or not, it is certain that much of the disease in man is caused by bovine bacilli. It has been shown that when tuberculosis arises by ingestion of food materials it is not essential for the primary symptoms to appear in the abdominal organs. Calmette and Guerin showed that tubercu- losis of the bronchial glands and lungs could result from feeding with tuberculqus material without any intestinal or mesenteric lesions being found. The flesh of tuberculous animals is, however, not necessarily infectious, for the muscular tissue rarely contains deposits of tubercle. McFadyean and Nocard, who injected large numbers of tubercle baciUi into the circulation, were unable to find any in the muscles, and the circulation itself was free in three to six days. Even in pigs, in which generalization is very frequent, observations have failed to show the bacilli in the muscles, although positive results have more often followed the use of the muscles of tuberculous pigs, sheep, and fowls, than those of cattle. Tubercle bacilli, however, abound in the glands, and their presence makes the flesh dangerous ; it is impossible to remove all the glands before the meat comes into the market. Besides the muscular tissues, all the internal organs are a common form of diet among the poor, the lungs, udder, and mesentery, being consumed in one form or another. These organs are highly infective, and from them arises a source MEAT: GENERAL CONSIDERATIONS 109 of danger to man. The Royal Commission made the following recommendations : The entire carcase and all the organs should he condemned when — (i) there is miliary tuberculosis of both lungs; (2) tuberculous lesions are present in the pleura and peritoneum ; (3) tuberculous lesions are present in the muscular tissues or in the lymphatic glands embedded therein ; (4) the carcase is emaciated. The carcase, if otherwise healthy, shall not he condemned, hut every part of it containing tuberculous lesions shall he seized, when — (i) the lesions are confined to the lungs and thoracic lymphatic glands ; (2) the lesions are confined to the liver, (3) or to the pharyngeal glands, or (4) to any combination of the foregoing to a small extent. The Effects of Cooking on Tubercle Bacilli. — Experiments have proved that the bacilli only show a moderate resistance to heat. Jersin found that their vitality was destroyed by exposure to 75° C. for ten minutes. Forster found an exposure of fifteen minutes at 65° C, ten minutes at 70° C, and one minute at 95° C, sufficient to destroy them. Woodhead, in his Report to the Royal Com- mission, working on the assumption that the flesh of tuberculous animals was rarely infective, unless soiled during the dressing of the carcase, injected tuberculous material into the flesh in some cases ; in others he smeared pieces of meat with the tuberculous matter, and formed them into " rolls," such as are sold by butchers. The " rolls " of a butcher commonly contain minced lung, omentum, and other tissues, which in tuberculous animals are highly infectious. Having prepared his " joints," Woodhead submitted them to cooking in the ordinary manner, and noted the temperature attained in the process. He arrived at the following conclusions : The centre of a " joint " weighing six or more pounds never exceeded 60° C. (140° F.) during ordinary cooking. " Rolls " of meat weighing 3 or 4 pounds were never rendered sterile throughout, and ordinary cooking could not be relied on to render tuberculous meat innocuous. Ordinary cooking was sufficient to destroy tuberculous material " smeared " on the outside of the meat. Boiling the meat was the most trustworthy mode of cooking it, roasting in an oven the next, and roasting in front of a fire the least effective method of securing its innocuity. Forster found that salting and smoking the meat were not sufficient protection against tubercle ; that tubercle bacilli could be found in the meat two months after such preservation. Neither does the gastric juice destroy the tubercle bacUli. Falk and Wesener exposed tuberculous material to the action of gastric juice for several hours, but it was stiU virulent when injected into animals. Stem has also shown that the intestinal secretions have no effect on the bacilli. We may conclude, therefore, that man can contract tuberculosis from cattle. But tuberculosis in man is probably not frequently caused by the ingestion of meat, since the swallowing of a large number of the bacilli is necessary for this mode to be effective. Furthermore, the no FOODS: ORIGIN, MANUFACTURE, AND COMPOSITION muscular tissue of animals is rarely infective, even in generalized tuberculosis, except by post-mortem contamination, and the ordinary methods of cooking the meat are more or less a safeguard against infection by this means. Finally, the Royal Commission found that during the period in which the consumption of meat as human food has greatly increased there has been a steady decline in the amount of human tuberculosis. The conclusion therefore must be arrived at that the risk to the community by eating the flesh of tuberculous animals is not so great as is generally assumed, and that this risk may be reduced by the more perfect and general inspection of meat and by efficient control of the market. Sale of Unsonnd Meat. — ^There is no law in the United Kingdom enforcing the examination of flesh foods before they are sold. But no person can expose for sale any animal, carcase, meat, fish, game, poultry, rabbit, etc., which is unsound without rendering himself liable to fine or imprisonment (Public Health Act, 1875, section 117 ; Public Health (London) Act, 1891, section 47). Seiznie of Unsound Meat. — ^Any Medical Officer of Health or Inspector of Nuisances may at all reasonable times inspect and examine any animal, carcase, meat, game, poultry, rabbits, fish, etc., exposed for sale or in preparation for sale and intended for the food of man ; and, if it appears to be diseased, unsound, un- wholesome, or unfit for the food of man, may seize the same and carry it away to be dealt with by a justice (Public Health Act, 1875, section 116 ; PubUc Health Amendment Act, 1890, section 28 (i) ; and Public Health (London) Act, 1891, section 47). Penalties may be imposed for obstructing the officer in the performance of his duty. CHAPTER V THE COMPOSITION OF BEEF, MUTTON, PORE, ETC. Meat consists of muscle, fat, connective tissue, cartilage, bone, etc. The proportion of water is determined by drying the substance for three or four hours at a temperature of boiling water, in a current of dry hydrogen, but without allowing the containing vessel to be in contact with the boiling water. The ash is afterwards ascertained by charring the substance at a low red heat ; the charred mass is then exhausted with water, the insoluble residue collected on a filter, burnt, and added to the residue obtained from the aqueous extract ; finally the whole residue is heated at a low redness until the ash is white. The proportion is then ascertained. Fresh meat contains an average of i per cent, of mineral matters, but the proportion may be as low as o'l per cent, in fresh unsalted pork. The fat varies from lo per cent, in some cuts of meat to 40 per cent, in side of, pork, and even 80 per cent, in very fat bacon. Meat as a rule contains imore fat than there is in fish ; lean fish, such as cod anri haddock, jscarcely contain any, but shad, mackerel, and salmon, have as much as 5 to 10 per cent. The proportion of fat is ascertained by extracting 2 or 3 grammes of the substance, dried;forthe determination of moisture, with anhydrous and alcohol- free ether for six teen hours . The ether extract is then dried by exposure to the full heat of boiling water in a current of dry hydrogen until it attains a constant weight. The proportion is then determined. The proteins of beef, mutton, and veal, vary in amount from 14 to 22 per cent, of the edible portion. The fatter the meat, the smaller the amount of' protein. Protein is more abundant in meat than in fish, becatise the latter contains more water. Among vegetable foods, the legumes and some nuts are the only members which really approach meat in their protein content, although some fungi have improperly been considered equal to meat. The mode of determining the proportion of protein is as follows : The nitrogen is determined by Kjeldahl's method, and the crude protein is found by the factor Nx 6-25. The albuminoids are then determined by Stutzer'g method, which is described thus :'■ 100 grammes of pure cupric sulphate- is dissolved in 5 litres of water ; 2-5 c.c. of glycerine is then added, and aiough solution of sodium hydrate to make the solution alkaUne. Filter. The precipitate so obtained is rubbed up with 10 per cent, of glycine, thus pre- paring a uniform gelatinous mass which can be measured jjat with a pipette. * Chemical News, 1892, ii. jg^ III ^ '" 112 FOODS: ORIGIN, MANUFACTURE. AND COMPOSITION The quantity of cupric hydrate per c.c. of the mixture is then determined. One gramme of the substance to be analyzed is added to loo c.c. of water in a beaker, heated to boiling-point, and a quantity of the cupric hydrate mixture, containing o-y to 0-8 gramme of hydrate, is added. It is filtered when cold, the precipitate washed, the filter and its contents put into the sulphuric acid, the nitrogen determined by Kjeldahl's method, and the protein reckoned from the usual factor. Wiley 1 finds the following method to be better : Bromine precipitates all proteins, including the products of digestion of albumin by pepsin, and gelatin, but it does not precipitate solutions of meat bases — creatin, asparagin, aspartic acid, etc. He therefore recommends that dry, fat-free animal matter be first obtained by washing the substance in cold or lukewarm water, and afterwards in nearly boiling water. This method removes all the soluble nitrogenous substances. He then determines (i) the total nitrogen in the entire sample ; (2) the insoluble nitrogen in the fat-free and washed sample when the factor Nx 6-25 gives the insoluble proteins ; (3) the solution is precipitated by bromine, and the nitrogen in the precipitate determined, and the same factor gives the soluble proteins (N x 6'2$) ; finally the nitrog- enous matters left in the solution are determined, and the factor Nx y\2 gives the amount of meat bases. Gelatin is determined by the factor NX5-5. The carbohydrates are almost absent from all animal foods, except milk. Glycogen is present in lean meat and liver to a variable extent, and some of the proteins (gluco-proteids) of meat have a carbohydrate complex. The Composition of Meat. — Konig says that meat contains an average of 15 per cent, of refuse, including bone, cartilage, tendons, fasciae, etc. The edible portion consists of water 75 to 77, muscle fibres 13 to 18, connective tissue 2 to 5, fatty tissue o;5 to 3-0, ash 08 to 18, extractives 05, per cent. The dry or water-free sub- stance is estimated by Riibner to consist of S3aitonini, myosin, and gelatin 701, haemoglobin and serum albumin 857, muscle albumin 3'i3, extractives I2'68, ash 5'5o, per cent. I. Muscle. — Lean meat consists of the muscular fibres, which contain many things. The proteins are myosin and paramyosin. Myosin is the chief substance of the sarcous elements or discs, and forms from 70 to 80 per cent, of the total proteins. It is a globulin, having the following composition — C 52-82, H 7-11, N 1617, S 117, per cent.^ The -paramyosinogen of Halliburton, or musculin of Hammarsten is present in small quantities. Fii.th says it is nothing but myosin. There .are also smsdl quantities of _s_erum albumin and globulin from the blood and lymph ; according TtT some observers, the latter are distinct bodies, called " myo- albumin " and " myoglobulin," similar to corresponding substances in the blood. There is also a slight trace of nucleo-protein in lean meat, arising from muscle cells, but the amount is insignificant, and few, if any, authorities take any note of it when considering a personal dietary. Lean meat also contains the sarcolemma of the muscle fibres, keratin and elastin from the bloodvessels, extractives or meat'bases, various non-nitrogenous extractives, fats such as lecithin, haeinoglobin or colouring matter, and mineral substances. ' Chemical News, 1S99, ii. 89. 2 Chittenden and Cumntin«;s, " Studies at Yale College," vol. iii., p. 115 THE COMPOSITION OF BEEF. MUTTON, PORK, ETC. 113 H ^^ <; Efl w S U P fe t/5 in ^ Oi 1! H > 1— I Bi Oh b P, 1-1 B. ?. W X U H 1 5 = mQ . >. "'E.'< s- g ■"•■sen's S J= 1-1 ■M a t) a c < twat onig twa Bry 28, cult part < M <1 ^. ., •o lo IT) "^00 i^O 00 O^JT'^O c "^ 1 1 t 1 1 1 '^ ■^ O^VO W »o«oO r*^t-«oo rs.rDO M f^tN. '- 1 11 1 1 1 ^ m ■^00 Ov W »o 11 t^\0 tN. rO M M COCO tN. ■^ a, *-i ro I-, i_M(Nt-i i-i.-.MN.-t u O00iHii^rots.«0 000000000000000 O^O ^^0^'^0 fow ■* p^o^o 0\00000 N tN.O>O00 o«t-i M M fH t-l l-l M MM M M MM 6£ •£2 "^v- 1 M 1 1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 '^^ C u )^ 000 t^o ^000 000000000000000 a *-■ t^fOt-t »^^o«^lxO^ xo 0^ Tf M M Cs. '^ io\D VO *o -^J- M SO tx b u-iVO i-t OM^ f i-t M M 00 M fOM ONrO^ro"^ ^00 O '^ O 00 c V *~i « 00 OlWMMM-^^W rONM^MM d ' 000000000000000 « t^»H N po^v^^i^»■^ QOVO OVOOOO W 000 0»ONts.O^I^ 00 r^O »o N -* \r\Q\C\0\ 0^ roVO "^ "^ t>.00 M 00 M i t-^'-"»r>o 000000000000000 fv -^ »^ M t% rooo ^ >0 fOOO fOfON N O\u^0 OvO 0*C0 VD ^ ^ 1000 00 fovo vo CO CO tj-co\o o^t-* N a»ooots.M tN.tN.O\ VO "^VO t>, tx bN tv tx *^ lOVO \D "^\0 -i • ^ >-i 4J U jJ a 1 « e (D C B« 1 ^ < 5« < M (S .«^^s.■^f^v 000000 00000000 a fi to 00 ^D "1 « MOOO VOOO t-iVO^ ^O^vO\ if] tb >o 0000 Ovo tN»vo inoo VO M tX-OVO -< Tj- li^ 0\ fO N 00 O»Q0 £ •E ro -^ KH ro M M 0 po rs.»o tN"^ m ro\0 •-" VO tN. •"" 00 o o 0. -^ «x mvo Tf -^00 "^\0 tN. 00 00 O^ O^00 00 00 0^ PL< NW<-«c)Ni-.i-.i-iM l-l HH M ^ h4 h4 hH o OOOOO^ONOO 000000 00000000 2 ro (s.a^inis.t^c^'^o f M I^ N Q0\O N s THE COMPOSITION OF BEEF. MUTTON, PORK. ETC. 115 T3 "O a n d a •^+5 n-u' (D a 0) rt +' d ■^ ca bo 1 5m 1 ^ n N "-» 0\ O* 0^ ■ corovo M n- M m 000 M t-< \r\ 'O t-v Ti- M bvfO on N ^ fO^ 0\ vo fO M M « pn CO c-1 " PO ro ro '^^ rn N ro\0 ■* u^ Q0\o vo TfVO tN. N o\ IH -t " n n r> n n n n n 000 n »o o^oo (S.C^"IXTJ- r^ ■*u^ 00 rOOO \r\ »^ u-i u-» CTiOO 00 p OlOO ^H. P) « 00 TKJ1-* 1^ tmr>VO rD ro CTi 0\Vf -* 10 o> I-I 00 irl OVOOOOOO^O tN>0 vo coONVO «vO 1-4 1^ '^ M " i-i M "" w "^ M M •^ "^ " « « kH •^ N *^ •^O O n 000 O n rom ro 10 N fo m 10 rrj Ol ^ Tf 0\ 0^ P* CO 00 00 *D\0 »o N. t^N N 9 ts* 0\ cOO» t^noo 0*0 00 »-« u^ ro fOO tN ^s.T^ t^ a» *H on vi n 0^\0 00 HI I-I ro 0\ ui PO Tl-t^-* Tj-ii^ u^ •*■* »^Tj- M f Ii6 FOODS: ORIGIN, MANUFACTURE, AND COMPOSITION U I % O o tn O a< o o w H i 1 Atwater and Bryant. Hutchison. Bull. 13, Bureau of Chemistry, U.S. Agricul- tural Dept. U . ■^^6 -^O^x foo»»-'*^« "^00 POM o»oo **> 1 I 1 1 1 III vn q tx iH « vq q q po ■-. « <> ■t'o -.VJ r? t 1 1 1 1 ' II' **^ -^ hT m" hT m" n w ci hT i-T « « m~ m « O u a V 9 S5 1 ?>? ?.?. ?.RR-§ §-?.8 8 8.8 ^8 8 S.^5 S.^ 5 5-o ^v\p Miop ^9 S* ? iirtO^Qw 6"^tN-«00ts txOO VO'Tj-W'^Chi-HO^MO'^ 0*«*l»-« 00O\ « »nt-twTff-«fr)««i«^<*lMroM«<*5T*>t-i <*^ 'S 1 00000 OOOOQOOOOOOOOoo "ivo O>ao t^ O <- r«*cp c^cp ^s 00 fo 1^ p \o ■* po ro "^ ■* >-' « ■'I- « 00 "^ ^("V^r* Tf^doM^ v6 00 do Ch 6\ 6^ M rs. 6* p^ ts. 6v -^ « 6* ^s. ^ so 6^ « «^ 1 OQOOO OOQOOOOOOOOOOO^'* ts^OO - 8 < Various organs : Suet, ox Suet, sheep-kidney . . Tongue, ox . . ,, ,, pickled Tripe Aries Banquet ,, Bologna Frankfort „ Holsteiner „ Lyons, ham Pork : Minimum Maximum . . Average ,, sausage-meat Salmi (bird's flesh) Pork.. .. „ Cambridge Polony Mutton German Horsemeat : Average Maximum Minimum THE COMPOSITION OF BEEF. MUTTON, PORK, ETC. 117 rt Co 'nJS ..-3 "Own pq a l« •a . a a 1s^ a hMh 13 Bl IH n -*-» rrt 1- m a OOVOOO'-'-^IN.OMOOTh lOVO »^00 \0 CO 00 rrj -^ M fo O O "^ O O "^ OCOVO M O^ ±J «00 M e^ i-« CO « ' o OOOOOOOOOOOO^MVO'^t>. roVO OOOOOOf^NO f^^OO w m <^ tN. ts. 0\ »000 -^W mo O 0\t>.rnO\*o ^00 00 -^ <^ M N 00 "^VO "O O ^n. ts. m 1^* m' (l^tlfWll^M'^^J-' W-Jl-MMW^' il4Ww4}-Tj-H*' M«VO»b^ CO « 00 t^ tN« f*^ CK ^s ^ rovo m Tf PTiOO ^ CO 00000000000 f«^CO "O N Ow>tN.OOOO 00 fOO Oi ''^CO "^ 0^ \p*p T*""^^^?* ^V^^^ fOp'OCp ^ o^vo tN. -^ c^vp CO o O o ^\o Qpoo Y^ VO 00 (H u-» O^ ■^ lOQo CO ^s.^o -^ 6 "^00 ■^\o M OOOOOOOOOOOyD*^ fOVO 0^0*00000000 t^OO tN.CO \o o^ cOhh O M'0'>0 0»"^"^COioO M 0**0w OVO txtNit^O^OO '^»OC» ^ ^'P^V^ M u^ 6^^ CO r^ CO CO ^\o 0\ o^vb ■^tJ-n ovc» ChcoiH u^oo ^ ^s.^O co ts.vo •*}■ ^ «MMC^M«MN««i-<«W«NC<^MfOMCl«MC»MP*N«t-.C0 COOO cofOOVO OOO^oO^M »H\o OicOVO l-^O'OOO'^^O do CO 6^00 •^co^'V'-* "^ »-* fN.b\6\6 ^ ^s4l-^^.^^.^s.o*o^N.■^"^M « »oi-i\o ^ CO »0 CO -^"O ^O 1010*0»«10"^10»0»J^»'^ ^"O "^^^O^-^U^^O^^fOM '^'^ ri| ? H s IS K .2 S 3 13^ q o pq ■a lu „ aj en r4 .•3 K pqHicn O — 'C .5 (u o o o ttj •71 i3_^ o . U o ■>sii « H O . 2 ^ S ElO <3 o o Ii8 FOODS: ORIGIN, MANUFACTURE, AND COMPOSITION < IS o M •A O o ^; o O s H H H 1 -o8o -240 trace 000 PO^O "^ POTJ-N \p POM ON M ^^ Ill < ? T V^ Oi 0» ^^. \0 POy» Tj- ^^.co M 00 10 co»o M tN. ON M ts. fO N^ i 5 lr>l 000 \0 -^to PO Y^N N PON 00 povo M V ■ ^ «*i o\ \p rocp 0*00 0^ PO ON fO ^\0 en M M\0 "O tN On VpNp N On PO M PO 1 tn c c 2^9 00 M M t-i to HI tN^M PO« o» •-. t^ M ^ * -« <^ 9 "' "^ PO« M roil W MOO On PO *o fO irj u-1 N N tN M N ^ ■ in 00 li^O 9 ^y* TfOO (S On *o i-« M M t^\0 M ^ooop C4 AnOO W « M M On M Tj-NONO \6 6 6 N PON »0\0 M 00 »0 PO Vobco = ■=! 1 op 0\\D 00 6^ N. « POM ro\0 »o \6 6 ^ « POM ONVO C « 6 "^ PO-^ « »X0 M TiJ-ioro ON M PO M « M 1 2 tH in po \0 0\M M 00 t^ M o»o Cn\0 ^ M PO MVp 7 ro^ON s rt ^ CO M vo ON On »o 00 PO PO CO "O "^ »nvO ■* f^OO « fvON ON •^»0 PO M M\0 Op On M OnVO N NO txlO ■ •' '-is '■ ■ ■■ ...it... ;;; ■4-1 ■• > 0) . . . 1... ;;; ■ JJ O -M • O B m THE COMPOSITION OF 'BEEF, MUTTON, PORK, ETC. 119 000 71- o o moo I \o -^ •^ M lovo "^00 00 *^ M l-H t-l CO fOO^WVO O *OfOO M M PO s s ? l-H "1 ^8 000 00 o\ 00 CO CO u-iCO « 00 ^t^t^vp r>. t-l W% lo ►H TtW p^o^ tJ- Ch "-" VI ^J^ ' o m 0\VD CO M T^\p 9 op op 0^ ^ fo t^ r^ M Cl IH l-< ^H VD N T^ tx Tt- ^ 6\ob o 3 3 pq ■* •* fncow « « fooo T^ >o ts. iTi r^ o « p ^op « V^O ov »/^ N. rrt\c> VO 00 SO t*^ M »^oo o '-' "^ ^VO fO "^ »o Tt" *^ "^ ^'^ "3 :•« r-a 3 C 3 •■d • e CD •d 5 !« cl d Id B cd a> o o v o o o v (U w QJ ^ V O PtO-" o ^ X s o en s CO OJ : ■!-> cvD g O g H 42 fi j - S a C3 00 •sa •°a 2 2 rt .. rt ^ . o o 3 •■ : . s 3 t« a 3 a 3 sp^p-s 2 ri hn2 3 O O 4> a^^a a-p-s > ^^0000 CLi PhP^IIi ■4-* «8 3 It g>3 a B S (S ^^3 OJ OJ OJ 120 FOODS . ORIGIN, MANUFACTURE, AND COMPOSITION The sarcolemma, or stroma-substance, deserves further mention. It consists of elastin, a sclero-protein. The proportion in muscle fibre of mammals varies from 7 to 16 per cent., according to the age of the animal. This proportion is of considerable importance by determining the digestibility, as well as the tenderness or otherwise, of the flesh. In the muscular tissue of young animals it is thin and delicate, but it becomes thicker and harder as age advances. The extractives are (i) nitrogenous and (2) non-nitrogenous. 1. The nitrogenous extractives, or meat-liases, are creatin, xanthin, hypoxanthin, guanine, camine, phosphocamic acid, inosinic acid, and sometimes leucomaines. Kaufmann considers urea to be a constant constituent of the muscular tissue of all the higher animals, but other authorities dispute this opinion. The proportion of meat- bases in flesh, and the quantity of purin bodies alone in flesh, are given in the table on p. 121. The leucomaines in fresh muscular tissue exist only in small quantities, but, according to Gautier,^ their presence is undesirable. The principal are as follows : Xantho-creatinin, C5H10N4O. Crusco-creatinin, C6HgN40. Amphi-creatinin, C9H19N7O4. Pseudo-creatinin, C4H5N5O. The proportion of leucomaines is liable to increase during " hanging," owing to the action of bacteria ; at the same time ptomaines may be produced. Gautier and Brown draw this dis- tinction between them : Leucomaines are vital alkaloids formed during life ; ptomaines are cadaveric alkaloids produced after death. The presence of extractives gives the characteristic taste and flavour to the meat ; indeed, the flavour depends upon small variations in the proportion of these substances. When they are • removed by boiling the meat is flavourless. The flesh of full-grown animals has more flavour than that of immature ones, and this corresponds to an increase in the proportion of the extractives. But feeding also influences the flavour : thus, the mutton fed on thymy heaths has a flavour which is unsurpassed ; the flesh of wild rabbits, from their eating aromatic vegetables, is far better flavoured than that of tame rabbits ; wild birds are always more highly flavoured than tame ones, and sea-birds have a flavour of fish. 2. The non-nitrogenous extractives are inositol (inosite), sugar, lactic acid, and glycogen. Inositol is said to be always present ; glycogen is always present in living muscle, but may be absent from dead meat. The sugar is small in amount, but some is always present in the form of dextrose and maltose ; and a little dextrin is obtainable." Sarcolactic acid is alwajre present in a variable proportion. Its influence in rendering the meat more tender by softening the stroma substance and connective tissues has been alluded to. ^ Maly's Jahres-Ber., xvi. 523. * Osborne and Zobel, Journal of Physiology, xxix. THE COMPOSITION OF BEEF. MUTTON, PORK, ETC. 121 H H < a W H Q < tn . < M wS o w «S OS CL| o M SC H O ;? I— ( I I/) a < S • ?c \rt fovD Tf in a» t^oo \o f^ •-< N y:) t^^ ■* C 3 ■^M ovHH r^^0\0 N -^O '^x "^ ^-i -2.2 i-i w tN 36 E~. so f)VO^ t-HVD loi^vo ^N^^VD 3\oo o\pi E« 0*-OK,i-iO\N»0'-irvO*^0\MMu^t^O C4 2s Oo. MMt-IW M H«0 ."•I- -' ->: H s £ vo **^vovo mvo iriiovo ^N^^\0 O\oo 0^^l to u OP'^t-M»^Hit^O"">O^MNmt-sO Ni-.MwOwO.-'MOOO.-'^-.OO.-' " Q m z fH u Ph .s CI o o Thoobvo 6 - OS O 00 Ot »H o\ >-• n »H >H M I-l 9 9 9 M invo o o <» N « 11 ppoop ppp Oi O *^ OS 00 0» HI n HI M M I-l o so o o> & ^ to CO ^ ^ H^ VO t*fcVO ts o\ op « yi en lo r^ob do CO M o ^ "^ « "^ -^\o NO CO ts.CO tN. g N OCp O y»0 « O O Q O »o rn O *o *6 I o .yi o o lo to m ^ lo O»0xro«t-«ro O^iHOO OOO fOOO O »« ^\0 O O O 00 *0 00 (N»vo ^^.oo VO 0\ *-> Q ■^to m o\vo vo f^to Ovesvoo^to lovo toiotoiovooom tntn lovo N xo vo to -^VO tovo to 000000000000 000000 00 00 000000 00 0000 0000 COOOOO I B all as. i -a 2 -St! ° S - ^a.8 S-as-g *■ +• Z^3 „-"SoaoS... 2 i a sS g g);^a ^ ^ < a J3 3 a a> 3 PL< S pq THE COMPOSITION OF BEEF. MUTTON, PORK, ETC. 125 to spare the proteid of 2 J ounces of meat ; and assuming that 25 grammes of gelatin were contained in this diet, this would only effect a saving of 35 grammes (ij ounces) of meat and 40 grammes (i^ ounces) of bread. One can realize from this that the usefulness of gelatin as a proteid-sparer in fevers and diabetes is of limited range." The hea't value of gelatin is equivalent to 3'88 calories per gramme. The intercellular substance of connective tissues consists of mucoid and a small proportion of serum globulin and serum cdbumin. Young tissues contain more than old ones. Mucoid is not true mucin, but a mixture of several gluco-proteins ; it contains 2 or 3 per cent, of sulphur. The composition of connective tissue is best obtained by the analysis of large masses. Composition of Connective Tissue. ' Components per Thousand. White Tissue (Achilles Tendon). Yellow Tissue (Lig. Nucha). Water Collagen . . Elastin . . Mucoid Protein . . Fat Extractives Mineral substanc '. .. .. es 628-70 315-88 16-33 12-83 2-20 10-70 8-86 4-70 575-50 72-30 316-70 5-50 6-l6 1 1 -20 7-99 4-70 The Manufacture of Gelatin. — Gelatin is manufactured from all nitrogenous waste materials or refuse — ^bones, connective tissues, skins (hides), hoofs, intestines, and even fish-bones, etc. The bones are crushed and boiled with a mineral acid to remove the inorganic salts. They are then digested, along with the softer materials about to be used, in a solution of caustic soda or lime for fourteen to twenty- one days to dissolve out the fat. Excess of lime or soda is after- wards removed by washing. The material is then transferred to an air-tight, cement-lined digester or vat, where the material is steamed to convert the collagen to gelatin. The liquid is removed in a revolving cylinder, strained at 100° to 120° F., and bleached by sulphurous acid. It is then solidified in layers, being afterwards redissolved, washed free from acids, bleached if necessary by char- coal, and dried at a low temperature in sheets, or on nets, or in vacuo. When prepared under proper sanitary conditions, gelatin forms a useful article of food for making jellies, etc. It should be free from impurities ; the presence of any quantity of mineral acids or sulphites would render it unfit for human food. There is little danger of properly-prepared gelatin containing micro-organisms, but such organisms have been found, including that of tetanus. 126 FOODS: OlilGIN, MANUFACTURE, AND COMPOSITION Composition of Gelatin.^ Nutrients per Cent. Calories per Pound. Water. Protein. Fat. Carbo- hydrate. Asb. Gelatin Isinglass Calf 's-foot jelly iy6 1 9-0 77-6 91-4 89-3 4-3 O'l 1-6 17-4 2-1 2-0 0-7 1. 70s 1,730 40s Gelatin dissolved in water in the proportion of i per cent, will set into a jelly ; but ordinary jelly usually contains 2 per cent., with some sugar, upon which its nutritive qualities largely depend. Jellies are readily digested, complete peptonization occurring in one hour. Jelly stimulates a flow of gastric juice, but at the same time fixes a good deal of acid ; it is therefore a useful food in cases of hyperacidity. We have already seen that, owing to certain deficiencies, it is not a tissue-former, but possesses the property of sparing the protein-tissues from destruction in a marked degree. Isinglass is considered in another chapter. 4. Cartilage. — The gristle of meat consists of cartilage cells with a hyaline matrix which is sometimes largely replaced by white fibrous or elastic tissue. The matrix consists of collagen, chondro-mucoid, chondroitin-sulphuric acid, and other albuminoid materials. The albuminoid is small in amount, and is a nitrogenous body loosely combined with sulphur. The chondro- mucoid is a gluco-protein, which is decomposed by dilute alkalies, and yields alkali albumin, peptone substances, chondroitin-sulphuric acid, and alkali sulphates. It contains 2-4 per cent, of sulphur. Chondroitin-sulphuric acid is one of the ethereal sulphuric acids (CjgH27NSOi7) . The collagen of cartilage yields a gelatin which differs from the ordinary kind by containing only 16-4 per cent, of nitrogen. 5. Bone has the following composition : Water 5 to 50, gelatin- iferous substance 15 to 50, fat 0"5 to 20, ash 20 to 70, per cent. It consists of cells, matrix, nerves, bloodvessels, and a large amount of mineral matter. The cells contain no keratin, and do not 3deld gelatin on boiling. The matrix consists of organic and inorganic materials. The organic substa.nce is ossein (identical with collagen) , a little mucoid and an albuminoid, and jdelds gelatin on boiling. The inorganic substance, bone-earth, is nearly the same both as regards proportion and composition in all animals. It is that which remains after complete incineration. The bone-ash of the ox^ has the following parts per 1,000 : Calcium phosphate, 877-2 ; magnesium phosphate, 15 3 ; calcium fluoride, 45 ; calcium chloride, 30 ; calcium carbonate, 1196 ; iron oxide, 13. The nutriment from bone consists of the fat from the marrow, albuminous substances from marrow and other cells, and gelatin, * Bulletin 28, U.S. Department of Agriculture. 2 Camot, Compt. Rend., cxiv. THE COMPOSITION OF BEEF. MUTTON, PORK. ETC. 127 amounting in all to 35 per cent. Bones require long boiling in order to obtain all this material, and it is better that they should be broken into small pieces, so as to present as many surfaces as possible to the water. According to Smith, 3 pounds of bone, when treated in a Papin's digester, will yield as much nitrogen as 7 pounds of meat; but this is chiefly in the form of gelatin, which we have seen is a valuable protein-sparer, but is not a flesh-forming food. The Composition of Oigans. Tripe consists of the stomach and intestines of the ox, properly cleaned and boiled. Its average composition is — Protein, 16 -8, • fat, 8 '5 ; and ash, 0-5 per cent. It consists largely of the involun- tary muscular fibres, etc., of the viscera. The chief protein is a globulin similar to, but not identical with, myosin ; it also contains a small amount of albumin, which coagulates spontaneously, but is not pure paramyosinogen. The connective tissue is mostly transformed into gelatin by boiling. It contains five times as much nucleo-protein as striated muscle ; it also contains a small amount of creatin, creatinin, glycogen, sarcolactic acid, and mineral substances, in which sodium exceeds potassium. A large propor- tion of these soluble substances are removed by the care required in its preparation as human food ; the corresponding deficiency in extractives renders it somewhat flavourless, but nevertheless a suitable food in cases where purins are not wanted. It is very easily digested. Liver is a very nutritious food. Average Composition of Liver. Nutrients per Cent. Water. Protein. Fat. Carbo- hydrate. 1-7 5-0 1-4 2-4 ■ 3-7 0-6 Ash. 1-6 1-3 1-7 1-4 1-7 1-2 1-7 Ox liver . . Calf liver Sheep liver Pig liver Chicken liver Goose liver Turkey liver 71-2 73-0 6l-2 71-4 69-3 62-6 69-6 20-4 19-0 23-1 21-3 22 '4 i6-6 22'9 4-5 5-3 9-0 4-S 4-2 15-9 5-2 The proteins of liver consist mostly of ferruginous nucleo-proteins, which yield nuclein on digestion, and are a source of uric acid in the system. When liver is boiled in water, a liquid is obtained contain- ing nucleo-proteins which are rich in nucleic acids. The protein obtained in this manner has been called fenatin ; when hydrolyzed by mineral acids, it yields nuclein bases and a pentose (xylose). There is also in the liver a smaU proportion of other proteins — 128 FOODS : ORIGIN, MANUFACTURE. AND COMPOSITION e.g., an albuminous substance which coagulates at 45° C. ; a globulin which coagulates at 75° C. ; a nucleo-albumin which coagulates at 70° C. ; and another protein belonging to the class of coagulated albumins.^ (a) The nitrogenous extractives of liver are important. According to Kossel,* 1,000 parts of dried liver contain i'97 parts of guanine, 1-34 hj^oxanthin, i-2i xanthin, a little adenine and uric acid, besides urea, leucin, cystin, and sometimes tyrosin. Walker Hall estimates the amount of these purin bodies in fresh liver as 0-275 per cent., or 275 grammes per kilo, or 19 -26 grains per pound. This amount is very high when compared with that in lean beef, mutton, or chicken. (6) The non-nitrogenous extractives are glycogen, paralactic acid, and sometimes inosite. The amount of glycogen varies from. 0-5 to 5-0 per cent. If the animal is in a poor or emaciated condition, the glycogen may entirely disappear, but in well-fed animals it ordinarily varies from 12 to 40 per 1,000 ; and if the animal is killed after resting and feeding, it may rise to 120, or even 160, per 1,000. The custom of resting and fasting the animal before killing it prevails, and tends to reduce the proportion of glycogen. It is not known whether any portion of the glycogen is combined with a protein, but Seegen found in the Uver a nitrogenous carbo- hydrate which he regarded as an intermediate in the production of carbohydrate from protein. Pat occurs in the liver as small globules, and sometimes large drops, in the cellular protoplasm. The amount varies from 4 to 15 per cent, in different animals and in the same animal, according to its condition. It is increjised by an excess of fat in the food, by fatty infiltration, and by the transportation of fat from other parts of the body. As a rule, a liver rich in fat is relatively poor in glyco- gen. Lecithin occurs normally in the Uver to the extent of 2 35 per cent. Cholesterin and jecorin (a protagon-like body) occur in small quantities. The latter contains both sulphur and phosphorus ; its exact constitution is unknown, but it contains a carbohydrate complex in its molecule. Among the minerals of the liver, iron is a regular constituent, and varies from 001 to 0-355 per 1,000. The greatest proportion of iron occurs in the liver of young animals ; it exists partly in the form of a phosphate, and partly as a ferruginous protein {vide supra). The liver also contains calcium, which in oxen amounts to 0-71 to 1-23 parts per 1,000 of the dried substance, besides salts of sodium, potassiimi, the alkaline earths, phosphoric acid, and chlorine. Owing to the compactness of its substance, liver is an unsuitable food for persons whose digestion is feeble or whose stomach is tender ; the large amount of nucleo-protein and purin bodies makes it unsuitable for the gouty. * Hammarsten's " Physiological Chemistry." * Zeit.f. Physiol. Chem., viii. THE COMPOSITION OF BEEF, MUTTON, PORK, ETC. 129 The Lungs. — It is presumed that the lungs of animals are not regularly used for human food, but that they are sometimes consumed is a well-known fact. The composition of ox lungs is — Water, 79-7 ; protein, 16-4 ; fat, 3-2 ; and ash, i-o — per cent. The nitrogenous bodies include elastic, muscular, and connective tissues ; besides fatty bodies, some glycogen or reducing substance, and probably cellulose. According to Robin, the salts are iron, 0-233; chlorine, i-igS ; phosphoric acid, 1-358 ; magnesium, 0-076; potassium, 0-741 ; and sodium, 1-213 — per 1,000. The Kidneys, like liver, are indigestible, chiefly by reason of the closeness of their texture. According to Atwater, the average per- centage composition is as follows : Composition of Kidneys. Nutrients per Cent. Water. Protein. Fat. Carbo- hydrate. Ash. Ox kidneys Calf kidneys . . Sheep kidne}^ . . 76-17 7S-80 78-70 16-6 1 6-9 16-S 4-8 6-4 3-2 0-4 1-2 1-3 1-3 The proteins'- are — ^Albumin, i-ii to 1-39; globulins, 8-6 to 9-25; other proteins, 1-43 to 1-59, gelatin; 0-99 to 1-84 — ^percent. The proteins, according to Halliburton, consist of a globulin and a nucleo- protein, but no albumin. But Liebermann^ recorded the discovery of a lecith-albumin — i.e., a compound of lecithin and albumin — and Lownberg, a mucin-like substance, or muco-protein, and traces of chondroitin-sulphuric acid. The nucleo-protein yields purin bases on digestion. The nitrogenous extractives or meat-bases are urea, uric acid, creatin, creatinin, xanthin bodies or purin bases, cystin (in ox kidney), leucin, and tyrosin. The non-nitrogenous extractives are glycogen and traces of inosite. This suprarenal bodies are usually torn off the kidneys when preparing them for food, and therefore are of little interest here. They contain the same kind of proteins as ordinary connective tissue, some salts, and inosite ; and a considerable amount of lecithin, glycero-phosphoric acid, neurin, xanthin and other parin bases, besides adrenalin and chromogen. A point of interest attaches to the fact that the injection of watery extract of supra- renal capsule into an animal is followed by glycosuria. The Spleen, commonly known as the " milt," is not eaten as meat, but is used for making gravy, soups, etc. It is therefore of con- siderable importance that its composition be known : Water, 69 to yy ; organic matters, 22 to 32 ; inorganic matters, 09 to 1-3 — per cent. It contains a large amount of nucleins, owing to its richness iii cells, and a large amount of extractives. The proteins, like those of the liver, are ferruginous. It also contains neutral fats, cholesterin, jecorin, inosite, and glycogen. The extrac- tives are chiefly xanthin bodies or purin bases, which Walker Hall * Gottwalt, Zeit. Physiol. Chem., iv. 431. ^ PflUger's Archiv, 50 and 54. I30 FOODS: ORIGIN, MANUFACTURE, AND COMPOSITION found in fresh calf's spleen to be o-i6 per cent., and consisted of uric acid, xanthin, hypoxanthin, and leucin. The spleen also contains paralactic, glycero-phosphoric, succinic, formic, acetic, butyric, and phosphoric acids, with chlorine, iron, sodium, and potassium. Aiter autolysis of the spleen, the following amino-acids are found : arginin, lysin, histidin, leucin, amino-valerianic acid, aspartic acid ; also tryptophan, proteoses, peptones, etc. (Hanmiar- sten). The dried zi>ater-Jree spleen has been found to contain as much as 5 per cent, of iron ;' it is present in organic combinations, mostly as haemoglobin. The Sweetbread. — According to Atwater, ox sweetbread has the following composition : Water 70-9, protein (N x 6-25) i6-8, fat i2-i, and ash i'6, per cent. This requires some explanation, which may perhaps be best given by a reference to the two kinds of sweetbread. The organ commonly sold by the butcher for sweetbread is the thymus gland, the pancreas being distingiiished from it as the " beUy sweetbread." The thymus gland, or " sweetbread,'' consists of a mass of cells held together by loose connective tissue. It is therefore very rich in nuclein or nucleo-protein, but is correspondingly poor in albumin and globulin. The principal substance is nucleo-histon, which forms 70 per cent, of the water-free substance ; it splits on digestion or hydrolysis with hydrochloric acid into leuco-nuclein and histon. The former is a true nucleo-protein — that is, a compound of nucleic acid and a protein rich in phosphorus. When a sweetbread has been kept a very little while some autolysis occurs, and the pyr- imidine bases — uracil and thymin — are produced. The fresh organ, however, contains some fat, lecithin, cholesterin, and glycogen, with smaller quantities of leucin, lactic acid, succinic acid, traces of arsenic, and iodothyrin. The ash includes potassium and other bases, the phosphates predominating. Lilienfield gives the following composition in parts per 1,000 : Proteids, 17-6 ; leuco-nuclein, 6879 ; histon, 867 ; lecithin, 751 ; fat, 402 ; cholesterin, 440 ; glycogen, 8'0 ; phosphates, etc. The pancreas, or " belly sweetbread," has a very similar composi- tion — i.e., a very small porportion of albumin and globulin, and a very large proportion of nucleo-protein, besides a variable quantity of purin bases, leucin, tyrosin,' inosite, lactic acid, some fat, volatile fatty acids, and salts, including calcium and magnesium. The nucleo-proteins are very important ; according to Hammarsten, one of these is the mother-substance of guanylic acid, and yields this substance, besides proteoses and peptones, on digestion ; another is the mother-substance of thymo-nucleic acid. Both these nucleic acids are transformed into purin bases. The purin bases obtained from sweetbread, according to Walker Hall, amount to 10 grammes per kilo, or 70 grains per pound. They exceed the amount in any other food, and include nuclein. xanthin, hypoxanthin, guanin, an