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Library ‘ornell Universit Essentials of milk hygiene; a practical t Cornell University The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924003023847 ESSENTIALS OF MILK HYGIENE A PRACTICAL TREATISE ON DAIRY AND MILK INSPECTION AND ON THE HYGIENIC PRODUC- TION AND HANDLING OF MILK, FOR STUDENTS OF DAIRYING AND SANITARIANS BY C. O. JENSEN Professor in the Royal Veterinary and Agricultural College of Copenhagen, Denmark. TRANSLATED AND AMPLIFIED BY LEONARD PEARSON Dean of the Veterinary Faculty of the University of Pennsylvania, State Veterinarian of Pennsylvania, Member of the Advisory Board of the State Department of Health, and Member of the Board of Health of Philadelphia. SECOND EDITION—REVISED ILLUSTRATED PHILADELPHIA AND LONDON J. B. LIPPINCOTT COMPANY CoryRieHt, 1907, By J. B. Lipprncotr CoMPANY CoPYRIGHT, 1909, BY J. B. LIPPINCOTT COMPANY Electrotyped and printed by J. B. Lippincott Company The Washington Square Press, Philadelphia, U. S. A. PREFACE TO THE SECOND EDITION. THat a new edition of this work is called for o year after the appearance of the first edition is gratif ing evidence of widespread interest in the subject milk hygiene. A few corrections and changes have been made the text and new matter has been added to give in det what may be regarded as the official method for tl examination of milk for bacteria and cells. L. P. AUTHOR’S PREFACE. (To THE ENGLISH EDITION.) In the hygienic movement of the times the control of the production and handling of milk has not been given a prominent place. But the significance of this subject is now plain and everywhere efforts are being made to institute such a control or to improve it. The efforts of cities to secure a wholesome supply of milk must of course differ and be adapted to local conditions, but they must all be governed by the same principles and rest on exact knowledge of the composition of milk and of the dangers that are to be avoided. In the preparation of this book it has been my hope that it would not only be of use to my Danish col- leagues, but that my colleagues in other countries would find it to be of service to them. For this reason I pub- lished a Danish and a German edition simultaneously and for the same reason I have been very glad to grant Prof. Pearson’s request for permission to prepare an English edition. C. O. JENSEN. TRANSLATOR’S PREFACE. Te production of market milk is a rapidly growing industry. The demand for milk in cities is continually increasing and there is reason to believe that the rate of increase will advance. The milch cow transmutes the pasturage and forage of the farm into edible protein, lactose and fat—into units of nutriment for man—at less than one-half the cost of similar units in beef produced by the steer. Milk is not only the most economical but, when pure and undefiled, it is among the most wholesome and it is the most easily digestible of all foods of animal origin. These are the strongest possible reasons for its extended use. On the other hand, there is no other food that, under ordinary conditions, is so exposed to contamination, that is so easily contaminated or that so fosters contami- nation as milk. Hence the necessity for the study of milk hygiene. The subject is a broad one. Milk hygiene involves some knowledge of the physiology of cows, especially with relation to breeding, lactation and nutrition; of comparative pathology, particularly the various dis- eases of the udder of the cow, the abnormal conditions that affect milk secretion, and the infectious diseases of cattle and of man that may be transmitted by milk; of bacteriology, in regard to the pathogenic organisms and the saprophytes that occur in milk, their effects, their behavior under various conditions and especially at different temperatures; of the chemistry of milk and its adulterations and, besides these, there must be added vii TRANSLATOR’S PREFACE certain, important chapters from animal husbandry, dairy husbandry and dairy industry. Until quite recently, milk inspection in the United States has been carried on by untrained men who have had little, if any, knowledge of the sources or nature of the contaminations of milk or of the means by which they must be avoided; their whole technical equipment has consisted in a few rule-of-thumb tests to detect gross adulterations. A large number of milk inspection services are still organized on this basis. In several cities, however, attention has been paid to microscopic and bacteriologic examinations of milk, and it has been shown that a very large proportion of the supply fails to meet even a moderate standard for cleanliness, thus re- vealing the need for measures at the seat of production and during transit to prevent injurious contaminations. It is becoming increasingly manifest to sanitarians that more must be done to protect consumers from the unwholesome conditions and the diseases propagated and transmitted by milk and the broader men in dairy industry realize that milk must be made safe and be pro- tected if it is to find and retain its proper place in the dietary of the people. This makes a demand for a discussion of milk hygiene from the standpoint of the sanitary supervision of market milk—from the side of the man who is to do the practical work of protecting the milk supply—and it is this demand that Professor Jensen’s book is planned to meet. Lzonarp Pearson. viii CONTENTS. PAGE INTRODUCTION sacedaaeeacieaaee eeu mana seuiinien< owes mnie’ 9 MILK AND ITS COMPOSITION.......cccccccccsccccucccecssecee 12 The milk glands and milk secretion; the constituents of milk; the composition of milk of different species of animals; variations in the composition of cow’s milk; changes in secretion during diseases of the udder; excretion of foreign matter with milk; changes in milk caused by micro-organisms; changes in milk at high temperatures. HARMFUL PROPERTIES WHICH MILK MAY POSSESS............-- 60 Exeretion of poisonous substances with milk; addition of preservatives; absorption of odors; transmission of infection from cattle to man; contamination with organisms of specific diseases of man; contamination with other bacteria; admixture of dirt. PASTEURIZATION AND STERILIZATION.........000 sie saieiwaag sav . 128 Pasteurization; sterilization. THE USE OF MILK FOR INFANTS. ...... 0c cece eeeees eee eeeeeee 147 The digestion of milk by infants; comparison of cow’s milk with mother’s milk; modified milks and special milk preparations; relation of milk to infant mortality. Pusiic CONTROL OF THE PRODUCTION AND HANDLING OF MILK... 157 Development of city milk supplies; laws and regula- tions for the control of milk; regulations regarding the production of milk; the health of the herd; feeding cows; care of the stable; milking; health of the attendants; the water supply; the care of milk on the farm; transportation ; regulations concerning sale and delivery; labeling milk; milk packages; public supervision to prevent adulteration ; methods of examination; sampling; specific gravity; fat determination ; total solids; adulterations and their detection; publie supervision to prevent the sale of deteriorated milk. ix x CONTENTS Tur MILK SUPPLY OF COPENHAGEN.......cecceccccccccccees 255 Appenpix I. German INSTRUCTIONS FoR PropUcING NURSERY MILK: ciesreseets arab ties new wea eae ae ain ead alteeans 265 ApPpEenpDIx II. THe MinK COMMISSION OF PHILADELPHIA....... 267 Apprenpix III. A Score Carp ror Darry FarMS.............- 273 Appenpix IV. THe Mink Commission or Essex Co., New JERSEY” go siins swe sais tesa coe a eR ak wie sow sare sala 275 Appenpix V. Report oF THE ROYAL COMMISSION ON TUBER- CUT SIS: 5 as cetias laa ody aba sabato) navies sapinva gy sud ocaya uaugtansiesareue one coue aye 285 MILK HYGIENE. PART I. INTRODUCTION. Cow’s milk has a peculiar place among our food stuffs in that it is not only an important and indispens- able part of the daily dietary of most people, but it is being used more and more for the feeding of infants and, indeed, is often almost the exclusive food for children during the first years of life. It is, therefore, quite natu- ral that at present when the science of hygiene is receiv- ing so much attention—especially in relation to the large cities—that there should be a demand for a reliable supervision of market milk. It is true that the milk trade in cities has been subject to a certain inspection, but attention has been directed to only one side of the question, to the possibility of adulteration, and to pro- vide that fat is not removed and that there is no alteration in the composition of the milk. From the standpoint of hygiene this is merely of secondary im- portance because it is in other ways that milk acquires dangerous properties and may, indeed, become the means of spreading virulent diseases. A properly organized milk control of the present ‘ day can not, therefore, be restricted to determining that milk offered for sale is unadulterated. On the contrary, it must be its chief purpose to prevent milk possessing injurious properties from coming into the market and to prevent market milk from acquiring such properties during the time that it is being handled and stored. Since it is possible only by means of a thor- ough, tedious examination to determine whether a given 9 10 MILK HYGIENE sample of milk is unwholesome, milk control can not be restricted to a simple inspection of the milk or to taking a sample for further examination. To insure real safety, the inspection must be broadened to cover the health and feeding of the catile, the cleanliness of the producing plant, the method of handling and caring for the milk and the condition of health of the people who come in contact with it. Milk control is, for the reason stated, more difficult and more expensive than, for example, meat inspection, and this is undoubtedly one of the principal reasons why the control of milk produc- tion and the milk trade is so defective in most countries. During recent years, a somewhat comprehensive con- trol of the milk trade in its various relations has been carried out in a number of large cities, but a thoroughly satisfactory system does not exist and will be difficult to establish on account of its cost. In Denmark, a long step has been taken in the matter of milk control through the voluntary initiative of a single large com- pany which, at a time when milk hygiene was receiving little attention, inaugurated a very comprehensive system of control, and thereby set an example that has been followed by other large companies, not only in Copenhagen but also in foreign countries. These com- panies have, in some respects, carried their control to a point far beyond that contemplated at the time by the public authorities. Copenhagen is on the point of supplementing its health laws in relation to the milk trade within its limits. As it is chiefly through the work of Veterinarians that meat inspection has gradually increased and is now conducted in a scientific manner, so, to a large extent, we have to thank the Veterinarians for the fact that the control of the production and sale of milk is grow- INTRODUCTION 11 ing steadily. Not only is important scientific work being carried on by them in several directions, which supplements the work of chemists and physicians, but the necessity for milk control is constantly being pointed out in meetings of veterinarians, in the International Veterinary Congresses and in the Congresses for Hygiene. A special journal is devoted to questions pertaining to milk hygiene, in conjunction with meat inspection, and separate courses in milk hygiene are given in many Veterinary Colleges. What follows is essentially the substance of lectures given by the author in the Veterinary and Agricultural College of Copenhagen. On some points in the prepara- tion of the book, the lecture notes have been expanded; for example, in citing the instances of disease resulting from milk possessing injurious properties. Since vet- erinarians are frequently consulted, by sanitary officers and by dairymen, in regard to the adulteration of milk, it is considered to be. desirable to discuss rather thor- oughly the composition of milk, the variations that occur under different conditions, and the adulterations. It is also considered to be appropriate to briefly treat upon the use of milk as food for infants. Division or SuBsEct The subject matter of this book is divided into the following parts: Milk and its composition. Injurious properties that milk may possess. Pasteurization and sterilization of milk. The use of milk for infants. In order to prevent the expansion of the book to unnecessary proportions, the hygiene of other dairy products as cheese and butter, and milk preparations as condensed milk, milk powder, etc., is not discussed. PART II. MILK AND ITS COMPOSITION. I. THE MILK GLANDS AND MILK SECRETION. Tus tissue of the milk glands is shown by macro- scopic examination (Fig. 1) to be composed of small lobules separated by bands of connective tissue in which lie the larger blood vessels, the nerves and the excretory ducts and in which there is sometimes a considerable quantity of fat tissue. The gland tissue itself is com- posed of complexly branching glandular tubes which, during the period of lactation, are provided with numerous globular distensions, so that the type of the milk gland is intermediate between that of the alveolar and tubular types. The glandular pockets are provided with a membrana propria (Fig. 2) and are lined with epithelial cells. In young and farrow animals, the cells are thin and square or high and narrow, and resemble superficial epithelium. During the period of lactation these cells become large and tense. This epithelium is usually composed of but a single layer, although, in old cows, it is sometimes found to be composed of several layers. Toward the end of gestation, the secretory function of the udder begins with the production of colostrum or the so-called ‘‘beast milk.’’ This is a thick, reddish or yellowish fluid with a taste more salty than that of nor- mal milk, and under the microscope (Fig. 3) it is seen that it contains numerous free fat globules and a large number of round or mulberry shaped cells—the so-called colostrum bodies—that are filled with fat globules. 12 parts of five others, Microphotograph. Shows individual glandular Section of the udder tissue of a cow. High magnification Micro. pockets with their endothelial lining and the connective-tissue framework. photograph. Colostrum.—The udder secretion of a cow that has recently calved. Stained lightly with osmic acid, causing the fat globules to become dark. Shows several colostrum bodies and fat globules. Microphotograph., Milk.- The fat globules are shown as light circles on a dark background. Micro- photograph. THE MILK GLANDS 13 Some cells are seen that have a distinct ameboid movement; these are leucocytes that have wandered through the epithelium into the glandular pockets and have taken up some globules of fat. Besides these, there are to be found some epithelial cells that have undergone more or less degeneration. The chemical examination of colostrum shows its principal constituents to be: water, proteids (especially globulin and albumin, and also casein and nuclein com- pounds), sugar, fats and cholesterin, and, besides these, lecithin, various salts and other substances in smaller quantities. Colostrum differs from normal milk in its higher percentage of solids and especially in its higher content of globulin, albumin, nuclein compounds and lecithin. The chemical composition of colostrum differs slightly among animals of different species. In the course of a few days, the secretion of colostrum passes into milk secretion so that at the expiration of about one week, the secretion possesses the characteristic ap- pearance and composition of milk. The microscopic picture of milk is quite different from that described above. A very large number of fat droplets (milk globules, Fig. 4) of varying sizes, and a small number of more or less degenerated cells (colos- trum bodies, gland cells) are distributed uniformly in a transparent fluid, the milk plasma. It was formerly thought that milk secretion differed in important particulars from other secretions in that, it was considered, it occurred through partial destruc- tion of the gland cells. It was supposed that during secretion the cells became longer and swollen, that the nucleus receded to the base of the cell while the part pointing toward the cavity of the alveolus became filled with numerous small fat globules. It was thought that after this ‘‘ fatty degeneration’’ reached a certain 14 MILK HYGIENE stage, there was a pouring out and solution of this part of the cell, that the fat globules were transformed into milk globules and the albuminous part of the cell protoplasm became part of the milk fluid and that the remaining portion of the cell, with the nucleus, was soon regenerated, whereupon a fatty degeneration again oc- curred in the regenerated portion of the cell. Recently, doubts have arisen as to whether, during the production of milk, there is, after all, a material disintegration of the cell protoplasm. Ottolenghis’s investigations appear to show clearly that milk secretion is an active cell process precisely as other secretions are, and that it does not depend upon the destruction of the cell. The destruction of entire cells and their elimination appears to occur only to a limited degree, but the presence of karyokinetic figures shows that, here and there, in the gland, such a disintegration does occur with consequent reproduction. The milk from animals of different species contains the same ingredients, namely: water, albuminoids (es- pecially casein and albumin), milk sugar (lactose), fats and inorganic salts. In regard to quantitative compo- sition, there are marked differences between the milks of animals of different species. Among the ingredients of milk it is supposed that casein is the direct product of the gland tissue, globulin of the broken down parts of cells, while it is not known whether albumin originates at the same source or comes from the blood. Concerning the origin of lactose, there are different opinions. Some investigators suppose this material is formed in the liver from glycogen or related materials, while others think, and indeed with reason, that it is formed in the udder by synthetic building up of glucose and galactose. The latter cannot, as such, have been taken up with the food, but must have been THE CONSTITUENTS OF MILK 15 formed in the body by a breaking down of the galac- tins of the food. Others regard lactose as a product of certain proteids (glycoproteids). Milk fat is de- rived partly from the fat in the food, partly from the fat tissues of the animal; but these fats undergo a material transformation in the tissues of the udder, so that certain easily recognizable fats, even when taken up in quantity with the food, are either not visible at all in the milk or appear in very small quantity or are merely transitory. Doubtless, milk fat—just as fat tis- sue—may also be derived from the carbohydrates of the food. Among the other ingredients of milk, citric acid does not originate in the food, but results from metabolism. - Milk secretion, to a great degree, bears the impres- sion of specific action of the cells which, however, may be influenced by external circumstances, but usually only temporarily. This is naturally of great importance for the young animal, which is nourished entirely or chiefly on its mother’s milk, as frequent and sudden changes in the composition of the milk would be harmful, if not dangerous. Milk secretion, it appears, may be checked through the influence of the central nervous system, but is regu- lated through the sympathetic nerve centres. In this connection, observations agree that certain irritant drugs (as pilocarpine) and other influences that decid- edly affect the secretory function of other glands, influ- ence milk secretion very little if at all; furthermore, section of the nerve trunks of the udder does not disturb secretion. Il, THE CONSTITUENTS OF MILK As already mentioned, milk of different mammals consists essentially of the same materials, namely: water, protein, sugar, fats and inorganic matter; but 16 MILK HYGIENE great differences are shown by quantitative analyses of the milk of the different species. Water. The quantity of water usually amounts to 80 to 90 per cent. of the weight of the milk; under certain circumstances and with some animals it is even consider- ably less. With the whale, the quantity of water is scarcely 50 per cent. Proteids. Of proteids, the three following are always found: casein, lactalbumin and lactoglobulin. A kind of albumose-like compound is sometimes found in insignifi- cant quantity—the so-called animal gum—which is also found in certain tissue and in the saliva, and probably comes from the breaking down of glycoproteids (mucin, etc.). Moreover, other proteids are often described as normal constituents of milk (albumins, albumoses, meat acids, etc.), but it is safe to conclude that these do not occur in fresh milk, while such compounds are readily formed by bacteria and ferments and can be formed by chemical means. Casein is a nucleo-albumin and, as such, it contains phosphorus. It is insoluble in water, but, by virtue of its property as an acid, it forms soluble salts with alka- lies. There are two series of casein salts, basic and neutral; the solutions of the latter have a milky appear- ance. Casein is found dissolved in milk in the form of a neutral lime salt, which aids in giving to milk its white, opaque appearance. When boiled, a solution of casein is overcast with a thin membrane of coagulated casein; but a real coagulation, as it occurs in albumins and globulins, does not take place. When the fluid has reached a certain degree of acidity casein coagulates at 75° C. and the precipitated casein is not again soluble. After the addition of diluted mineral acids or of acetic acid, casein is precipitated as flakes or lumps, but under- goes no chemical change and is again easily soluble in THE CONSTITUENTS OF MILK 17 lime water and diluted alkalies. The separation depends only and solely upon the breaking down of the casein calcium compound. By rennet (chymosin, etc.) casein is precipitated as flakes (human milk and donkey milk), or as a firm gelatinous mass (e.g. cow’s milk). The dif- ferent modes of precipitation do not appear to come from the differences in the casein, but are due to the dif- ferent salt content of the different kinds of milk. Under the influence of chymosin, casein is transformed into paracasein, which in its compound with lime is insoluble in water and, therefore, may be precipitated in this way. The action of the rennet ferments is quite different from the precipitation of casein by acids. With the pre- cipitation of paracasein, an albumose-like proteid re- mains in solution (whey proteid), so the action of the rennet ferment is to split the casein. By the growth of bacteria in milk, the casein is often thrown out of solution, either as a result of the formation of acids or by the chymosin-like effect of ferments produced by bacteria. Sometimes the separation occurs from the joint action of the ferments and the acids that are formed. In pepsin digestion, casein is dissolved with the formation of albumoses (caseoses) and paranuclein, which is rich in phosphorus. In the organism, para- nuclein is dissolved by the pancreatic juice, is absorbed, and is excreted with the urine as phosphoric acid. It has often been said that casein, as it is found in the milk of different animals, is not the same and, as evidence of this, reference has, incorrectly, been made to the different ways in which casein separates from milks acted upon by rennet. A more important indica- tion, although the observation requires confirmation, is in the claim that in the pepsin digestion of human milk no paranuclein is formed. According to Hammarsten’s thorough work, casein appears to show no chemical dif- 2 18 MILK HYGIENE ference in different kinds of milk. The latest investiga- tions concerning the powers of the living animal to form specific anti-albumins (precipitins) following the injection of albumin solutions, prove, however, that the casein of different species of animals has certain dif- ferences, even though these are so slight that they can- not be detected chemically. The lactalbumin is very similar to the albumin of the blood, but it appears to differ from this in some particu- lars. It coagulates at about 70° C., and, like all other albumins, it is not precipitated in a neutral solution of sodium chloride and magnesium sulphate, but it is precipitated in a saturated solution of ammonium sulphate. The lactoglobulin occurs in milk in very small quan- tity, merely in traces, while colostrum is comparatively rich in this substance. It coagulates at 75° C.; it is pre- cipitated in the same way as serum globulin and, like serum globulin, is insoluble in water, but is soluble to some extent in weak salt solution. Carbohydrates. Of the carbohydrates, lactose, or milk sugar, occurs as a constant constituent in the milk of the cow and of most other mammals. Some investiga- tors claim that in colostrum there is a monohexose, which is probably glucose, and it is not unlikely that in the milk of certain animals other kinds of sugar appear; for example, it is cited that a peculiar kind of sugar, tewficose, is found in considerable quantity in the milk of the Egyptian buffalo. : Lactose (C,,.H..0,, + H,O) is a disaccharid which is split by hydrolysis (e.g. by means of heating with dilute acids, action of ferments) into glucose (grape sugar) and galactose as follows: Cy, He, OW + H,0 = C, Hy O. + C, Ay O. Lactose Glucose Galactose THE CONSTITUENTS OF MILK 19 Lactose has been found only in milk and must be formed in the organism; but this formation, as has already been stated, is not yet thoroughly understood. Commercial lactose is derived from whey as hard rhom- bic crystals which have a slightly sweet taste and are soluble in six parts of cold water. By the action of micro-organisms, lactose may ferment in different ways. Certain yeasts and bacteria cause an alcoholic fermen- tation, while other bacteria split lactose, forming lactic acid (causing ‘‘ souring ’’ of milk) and several other substances as by-products (CO,, H, formic acid, butyric acid, etc.) ; still other bacteria form as their chief pro- duct, butylalcohol, succinic acid or acetic acid. Certain moulds are able to form oxalic acid from lactose by oxi- dation. Lactose, like glucose, reduces Fehling’s solution when heated. Fats are found in the milk as small droplets or glob- ules, which accumulate upon standing into a layer of cream, and which are easily separated from the other constituents of milk by means of centrifugal force. Upon shaking milk or cream, the globules of fat grad- ually coalesce into larger drops and lumps (butter). It was formerly thought that the fat globules were sur- rounded by a membrane, but now it is generally believed that it is not so. However, under the microscope one can see a border on certain individual fat globules,. which is to be regarded as a remainder of broken-down cell protoplasm. Milk fat consists of a mixture of different fats, the principal of which are olein, palmitin and stearin, which are the neutral triglycerides of the correspond- ing fatty acids. Besides these are found the triglycer- ides of myristic acid and of butyric and capronic acids (the last two volatile) and also traces of triglyceride of other fatty acids (caprylic, caprinic, laurinie and arach- 20 MILK HYGIENE inic). The composition of the fat is subject to numerous variations and these are not alone racial peculiarities, for individual traits, the composition of the food and external conditions of life not infrequently influence it. Other Substances. Milk contains other substances in very slight quantities: urea, kreatin, kreatinin, leci- thin, cholesterin and citric acid. It is not yet known if these appear in the milk of all animals or whether some of the substances are characteristic of certain animals only. Besides these substances, milk contains some inor- ganic salts in solution, which remain after evaporating and burning the milk. The ash consists of lime, potash, sodium, small quantities of magnesia and traces of oxide of iron in combination with phosphoric acid, chlorine and sulphuric acid. The small surplus of basic sub- stances in the ash were in combination with citric acid and, perhaps, with other organic acids. Phosphoric acid and lime exist partly as soluble compounds, partly in combination with casein. A little di- and tri-calcium phosphate are held in solution by the action of the casein and are therefore precipitated with it. The milk of dif- ferent species and sometimes of different individuals, shows a quantitative difference in the ash. According to recent investigations, milk, at least cow’s milk, always contains a ferment, the so-called galactase (Babcock, Russell), which is capable of slowly peptonizing protein. The significance of this ferment and its composition are wholly unknown to us; possibly it comes from the breaking down of the leucocyte (Barthel). Certain gases occur in the free state in milk. Investigations on this subject have given varying re- sults, in that some investigators have found distinct quantities of oxygen in milk just drawn, others have THE COMPOSITION OF MILK 21 detected only a trace, or none at all; moreover, milk always contains considerable carbonic acid and a slight quantity of nitrogen. Upon standing, this relation changes, for carbonic acid escapes and oxygen is absorbed.! NI. THE COMPOSITION OF MILK OF DIFFERENT SPECIES OF ANIMALS It has been stated that the milks of different species of animals consist of essentially the same materials, but that in their quantitative composition they show quite a little difference. As will be considered in detail later, there are great variations with individual animals and, therefore, the figures given are to be regarded as aver- ages and they are to be accepted with some reserve, for not all are the result of a sufficiently great number of analyses; still, they give quite a good picture of the striking peculiarities of the different kinds of milk. Cow’s milk is white, opaque, has a slightly sweetish taste and a very slight odor. It shows amphoteric reac- tion to litmus paper, e.g., it colors red litmus paper blu- ish and blue reddish. To other indicators, milk some- times shows itself to be acid, sometimes alkaline. Ac- cording to Courant, it can be demonstrated that 100 c.c. of fresh cow’s milk shows the same amount of alkalinity toward blue litmus as 41 cc. of a one-tenth normal solu- tion of sodium hydrate and the amount of acidity, as measured by phenolphthalein, is equivalent to that of 19.5 cc. of a one-tenth normal solution of sulphuric acid. However, milk does not always react the same, it changes especially during the course of the period of lactation. The casein of cow’s milk is precipitated 1 Richmond says: “As the milk is kept the amount of oxygen decreases and that of carbon dioxide increases; this is probably due to aérobie microérganisms, which absorb the oxygen and give out carbon dioxide.” [L. P.] 22 MILK HYGIENE by chymosin as a firm, jelly-like mass. The butter-fat contains a yellow coloring stuff. The qualitative composition of cow’s milk averages as follows (Fleischmann): water, 87.75 per cent.; fat, 3.4 per cent.; casein, 3.0 per cent.; albumen, 0.5 per cent.; lactose, 4.6 per cent.; salt, 0.75 per cent.? Lacto- globulin and lecithin are found only in very slight quan- tity; citric acid is found in quantities of from 0.1 to 0.15 per cent. Analysis of the ash shows its constitu- ents to be present in the following proportions: K,O Na,O CaO MgO Fe,0O,; P,0O;, Cl 80, 25.81 11.78 19.71 2.77 0.13 23.11 16.15 407% But there may be a considerable amount of variation, especially in the potash, magnesia, chlorine and sul- phuric acid, since the consumption of certain salts in great quantity cause changes in the composition of the ash. The quantitative composition of cow’s milk varies greatly among the different breeds and individuals, and at different stages of the period of lactation (see the next section). Zebu’s Milk coincides almost wholly in its properties 2 Richmond gives the following average composition of milk, based on the analysis of 200,000 samples taken from the supply of a dairy company in London: Per cent, Per cent. Water icici seins 87.10 Casein ..........-. 3.00 PAG ocncs ai on aecuerns 3.90 Albumin... ...... 0.40 Milk sugar ........ 4.75 SAS crccaceracdeeres serene 0.75 A very large proportion of the cows producing milk for the London market are of the Shorthorn breed. [L. P.] The following is taken to represent “milk of good average quality ” in Massachusetts : Per cent. Per cent. Water oca cee capeates 87.00 Casein ..........-- 3.00 Bat ssishsmy daira ecsenie's 4.00 Albumin .......... 0.50 Milk sugar ........ 4.80 ASB. 65 00a seececees 0.70 (Bulletin 110, Hatch Experiment Station.) [L. P.] THE COMPOSITION OF MILK 23 and quantitative composition with ordinary cow’s milk. Buffalo’s milk, which possesses a slight, pleasing odor and taste, is richer in solids than cow’s milk, since the quantity of fat amounts to about 8 per cent., the proteids to fully 4 per cent. and lactose to 4.75 to 5.2 per cent. Goat’s milk is pure white, without especially pro- nounced odor or taste. If, however, the milking takes place in the stable in which male goats are kept, the milk very easily absorbs the same characteristic un- pleasant odor. The chemical composition of goat’s milk is similar to that of cow’s milk; frequently, though, the fat content is a little greater. The butter-fat is white. Sheep’s milk is a whitish yellow, rather thick and pos- sesses a peculiar, somewhat unpleasant taste and odor. It differs from cow’s milk and goat’s milk in its high fat and casein content, averaging about 9.0 per cent. and 6.3 per cent. respectively. Moreover, the fat content is very variable, for with some breeds it amounts to 11 to 12 per cent. and even more, while with others it amounts to only 2 to 3 per cent. The examination of milk of 2,700 sheep (Sartori) showed an average specific gravity 1.0374 and the following composition: water 78.70 per cent., fat 8.94 per cent., proteids 6.3 per cent., lactose 5.06 per cent., ash 1.015 per cent. The average analyses for 250 other sheep (Fleischmann) were as follows: water 75.54 per cent., fat 11.90 per cent., casein 5.83 per cent., albumin 1.33 per cent., lactose 3.43 per cent., ash 1.05 per cent. Mare’s milk is usually distinctly alkaline to litmus, but may be neutral. It is white or bluish in color and has a somewhat pronounced sweet taste due to its high lactose content (about 6.6 per cent.). The proportions of fat and proteids are conspicuously small; as in the averages of 15 analyses (Veith) only 1.09 per cent. fat and 1.89 per cent. proteids (of which about a third was 24 MILK HYGIENE albumin) were present. The inorganic salts (ash) are present only in small quantity (0.31 per cent.). Ass’s milk is essentially the same as that of the mare; it has in common with the latter the low fat and proteid content and the large quantity of lactose. The composi- tion is given somewhat differently by different writers. Ellenberger, Seeliger and Klimmer found as the aver- age of a large number of analyses: water 91.20 per cent., fat 1.10 per cent., proteids 1.50 per cent., lactose 6.0 per cent., ash 0.40 per cent. The reaction is decidedly alka- line to litmus. On account of the small proportion of salts, the casein is precipitated by rennet as a flocculent, disunited mass. Milk of the ass more nearly resembles human milk than does that of any other animal, and in Southwestern Europe, for the most part, milk of the ass is the principal substitute used for the nourishment of infants. Woman’s milk, which reacts amphoterically, is regu- larly somewhat richer in lactose than cow’s milk, but it contains less proteids and also less ash, especially phos- phoric acid and lime. While the lactalbumin in cow’s milk constitutes but one-fifth to one-sixth of the protein, in human milk during the first part of the period of lactation, albumin and casein are present in almost equal quantities; later, casein increases a little. The average percentage of fat is approximately the same as in cow’s milk, but it varies considerably, from 1.3 per cent. to 7.8 per cent. Human milk is richer in lecithin, but poorer in citric acid (about 0.5 per thousand) than cow’s milk. According to E. Gottlieb the following numbers represent the average composition of 104 sam- ples: water 87.92 per cent., fat 3.43 per cent., casein 0.58 per cent., albumin 0.52 per cent., lactose 7.12 per cent., ash (salts), 0.25 per cent. Woman’s milk is subject to individual variations to a great degree, as is shown by THE COMPOSITION OF MILK 25 the table below, which is taken from Gottlieb’s analyses: Water. Fat. Casein. |Albumin. | Lactose. | Ash. “Normal”? milk....... 87.52 3.38 0.78 0.39 7.51 0.27 Rich milk............. 85.24 | 5.91 0.87 0.36 7.24 0.24 Poor milk ............ 89.65 1.66 0.57 0.27 7.47 0.23 Each number represents the average of four analyses taken several days apart. Each sample came from a young woman who had been confined a few months before. It has often been said that casein in human milk dif- fers chemically from that of cow’s milk; but, as stated above, according to the investigations of recent years, there is good reason to believe that this is not the case. (Hammersten, Cohnheim.) Sow’s milk is thick, slimy and of alkaline reaction. In chemical composition it is very variable, especially so in regard to the fat content which varies between 1.0 per cent. to more than 12.0 per cent. In some of the analyses reported, it appears that a distinction has not been made in relation to the proportion of fat of the milk that was drawn first and that drawn last, but since the other ingredients of the milk were found in different proportions, the variation can not be doubted. The quantity of protein averages about 6.0 per cent. but may vary from 5.7 to 15.5 per cent. The quantity of lactose varies from 2.0 per cent. to 3.8 per cent., the ash from 0.77 per cent. to 1.18 per cent. On the whole, it may be said that sow’s milk is quite concentrated. Bitch’s milk is also quite variable in its composition. The fat content varies between 4.0 per cent. and 12.0 per cent., the pro- portion of casein between about 3.5 per cent. and 6.0 per cent., albumin is present in about the same quantity as casein, there is about 2.0 per cent. to 3.0 per cent. of lactose and about 1.0 per cent. of ash. The milk of the cat has not received much study. According to some analyses that have been made (by Cornaille), it is of about the 26 MILK HYGIENE following composition: fat 3.33 per cent., casein 3.12 per cent., albu- min 5.96 per cent., lactose about 4.9 per cent., and ash 0.59 per cent. The rabbit and the reindeer give milk particularly rich in fat and especially concentrated, but poor in lactose. The milk of the elephant shows very great fat and sugar content and comparatively little protein. A milk differing greatly from the usual is that of the whale. It contains only from 41.0 per cent. to 48.0 per cent. of water, and fat in the enormous proportion of 43.0 per cent. to 45.0 per cent. There is 7.5 per cent. to 11.0 per cent. of protein and only about 1.3 per cent. of sugar. The table below shows the average analysis of human milk and of the other kinds of milk used as food for man: Cow. Goat. Sheep. ASS. Mare. | Woman. Water ..........2.0085 87.75 | 87.30 | 75.54 | 91.20 | 90.00 | 87.92 CARON. sca seceateaceciey s 3.00 3.00 5.83 0.90 1.26 0.58 Albumin.............. 0.50 0.50 1.33 0.60 0.63 0.52 Bat: osc cswivesaandeesss 3.40 3.90 11.90 1.10 1.09 3.43 Lactose sis evseuies sss 4.60 4.40 3.43 6.00 6.65 7.12 Baltic aso seicieseee ces 0.75 0.80 1.05 0.40 0.31 0.25 IV. VARIATIONS IN THE COMPOSITION OF COW’S MILK It has already been stated that the composition of the milk of the cow, as well as that of other animals, may vary more or less. So far as the variations of cow’s milk are concerned, they are not very great, still they are of sufficient importance to make it necessary to take them into consideration in connection with its pro- duction, sale and control. The above figures give ap- proximately the average composition of cow’s milk and, of course, correspond with the composition of market milk, which consists of a mixture of milk of several or many cows.’ The separate constituents vary in quantity 8 These are Danish figures; in America the average for market milk is higher. [L. P.] VARIATIONS IN COW’S MILK 27 in different degrees, the fat content varying the most, the albumin, lactose and ash ingredients less. In ‘« rich ’’ milk the fat content often considerably exceeds the average, while the proportions of protein and lac- tose are never much higher than the averages given. On the other hand, with thin, poor milk the fat per cent. may fall far below the average, while the proportions of protein and lactose depart but slightly from the average. ‘These variations are not due merely to the elimination of water from the milk, that is, to a simple concentration, but rather to a qualitative variation in the activities of the gland cells. Just as is the case with other glands, the milk glands may be stimulated to greater activity, so that the quantity of secretion increases, but its chemical compo- sition is not disturbed, or only slightly, or temporarily, until the gland tissue has accustomed itself to the new condition. Drinking a large quantity of water causes no increase in milk secretion; the gland cells do not secrete more water than the quantity required to maintain the proper proportion to the milk solids. Food containing much water has no permanent effect upon the composition and the quantity of the milk. The influence of such materials as pilocarpine and atropine, which increase or reduce other secretions in a great degree, have no direct, or only a very slight influence on the milk secretion, apparently because this is con- trolled by the sympathetic nerve centres. The various conditions that have, or are believed to have, an influence upon the chemical composition, and especially upon the fat content of milk, are considered in the following para- graphs. 1. Breed peculiarities. Cows of different breeds give milk of somewhat different composition. In gen- eral, it is believed that breeds from the highlands and 28 MILK HYGIENE mountainous regions give a richer milk, while breeds from the lowlands yield milk poorer in fat. There are, it is true, exceptions to this rule, e.g., the Allgauer and the brown Swiss cattle give rather a poor milk, while the Devons and the Normandy cattle give milk rich in fat. As an example of breeds that give milk especially rich in fat we may mention the Jerseys and the Guern- seys, whose milk contains an average of 4.5 per cent. to 5.5 per cent. fat, also the Harz cattle, whose milk is reported to contain an average of 5.8 per cent. fat. On the other hand, milk of the Swiss cows has only 3.0 per cent. fat, that of the Angler and Breitenburger and other breeds only about 3.13 per cent. to 3.15 per cent. fat. The average of the Danish breeds can hardly be placed higher, being about 3.2 per cent. to 3.4 per cent. fat. 2. Individual peculiarities. The figures given above are averages only. The milk of different individuals varies more or less so that in the same breed there are individuals that give milk rich in fat, and also those whose milk has a percentage of fat below the average of the breed in question. The production of rich milk is, therefore, a distinctly individual property that is due to the physiological peculiarities of the gland cells of the animal, and which appears, to a great degree, to be hereditary. Among cows of the same breed may be found some whose milk contains 4.0 per cent. or more of fat and, on the other hand, there are many that give milk containing only about 2.5 per cent. fat; indeed, not infre- quently the percentage of fat is still lower, and from Germany there are records of cows that give milk con- taining not more than 1.5 per cent. of fat. Such cows are frequently and in large numbers excluded from the best herds, so when herds are made up of purchased cows, the mixed milk from such cattle often contains but VARIATIONS IN COW’S MILK 29 little fat and may not exceed 2.25 per cent. to 2.75 per cent.4 While it is scarcely possible, as will be discussed later, to influence the composition of milk materially or permanently by alterations in the quantity and com- position of the food, still it may not be entirely impossi- ble to influence the young animal by skilful or by appropriate feeding in such a way as to encourage it later to produce milk rich in fat. But thoroughly reliable data on this point are not available. 3. The age of the cow. Although the quantity of milk varies according to the age of the cow, so that it is usually greatest during the third to the fifth lactation periods, the chemical composition appears to remain almost unchanged from year to year (Hittcher) ; yet it is apparent that fats as well as other ingredients decrease with great age. 4. The stage of the lactation period. The colostrum secretion is not especially important. The true milk secretion very quickly attains a considerable volume, but falls off gradually after a longer or shorter time, until the secretion ceases altogether or is insignificant to- wards the end of the period of gestation. Some cows, however, continue to milk very well up to calving and to the new period of lactation. It was emphasized above that colostrum differs essentially, both morpho- logically and chemically, from normal milk. Further- more, the composition of milk during the first part of the lactation period differs from that secreted toward the close. a. Colostrum. The first colostrum is whitish, yellow- ish, or even reddish to brownish; it is slimy and has a 4It should be borne in mind that the cattle here referred to are of heavy milking lowland breeds not represented in America. [L. P.] 30 MILK HYGIENE specific gravity of 1.040 to 1.080. Its microscopic ap- pearance has been described before and, in part, its chemical composition. Gradually, the appearance and the composition of the secretion changes until, in the course of about a week, it becomes pure milk. This gradual development is illustrated by the following analysis given by Eugling: Number of hours after calving. Normal milk. dintely. 10 oy 48 72 Waters. ccseuciscirate ss 73.17 | 78.77 | 80.63 | 85.81 | 86.64 | 87.75 Casein .c.ccse5 sda seas 2.65 4.28 4.50 3.25 3.33 3.00 Albumin Globulin fC" 16.56 9.32 6.25 2.31 1.03 0.50 Extractives ........... 3.54 4.66 4.75 4.21 4.08 3.40 SUgar ss scceanecs cases 3.00 1.42 2.85 3.46 4.10 4.60 AGh. . jhsisenveh ec aeaar 1.18 1.55 1.02 0.96 0.82 0.75 These figures show that the chief difference in the composition of milk and colostrum consists in the greater albumin and globulin content of the latter, which arises partly from the presence of numerous colos- trum bodies, in consequence of the presence of which colostrum coagulates when heated. Another important difference is the low sugar content of colostrum ; accord- ing to Tereg the sugar of colostrum is not lactose, but is grape sugar, or perhaps a mixture of this and galactose. Of the substances that are extracted with the fat, about 13.8 per cent. consists of cholesterin and 8.0 per cent. . of lecithin. Among other peculiarities shown by colostrum of the cow may be mentioned its acid reaction and the fact that after the addition of rennet it does not coagulate at all, or only very slowly. b. Milk. Shortly after calving, while the secretion VARIATIONS IN COW’S MILK 31 is abundant, the milk is generally a little less rich in solids and especially in fat than it is later when the secretion begins to fall off; with some cows the differ- ence is not very great, but with others it is considerable. In the last month the secretion falls off rapidly and often ceases entirely; at the same time the proportion of solids usually increases and this is especially the case in relation to fat. The milk gradually acquires a decided alkaline reaction to litmus paper and not infrequently develops a salty taste. The changes in composition are shown in the following table, which gives the results of analyses, made by Fleischmann, of the milk of one cow which calved January 28th. With this cow, the percentage of fat during the period of lactation rose from 3.033 to 8.300; but this significant increase occurred almost entirely in the last month when the cow had become an old milker. At the same time the quantity of albumin, lactose and salt. (i.e., solids not fat) increased only from 8.14 per cent. to 9.00 per cent. The chemical composition of milk of some cows does not change noticeably during the whole period of lac- tation, and the percentage of fat as well as the other solids may even fall off a little at the end of the lactation period. Fleischmann gives a table showing analyses of the milk of such a cow for the whole lactation period: the daily quantity of milk in April was 19.84 kg., on the 31st of January following it was 3.6 kg. The fat per- centage, which had varied between 2.56 and 2.97, fell in January to 2.42, 2.60, 2.32, and 2.48 upon different analyses. The percentage of solids not fat also fell a little. 5. The time and method of milking. It is commonly believed that there is always a slight difference between the chemical composition of the morning and the even- 32 MILK HYGIENE ing milk in that the latter is richer in fat than the for- mer. Numerous investigations have given very varia- ble results that may be explained by the short duration of the test, by the daily variations of the composition of the milk, ete. Some larger experiments relating to LACTATION PERIOD Daily ; Solias |Fatcontent quantity | Specific Fat. not fat, | Of the total of milk. gravity. Per cent. Per cent. ence & April eisiciciloctey eceieda 11.55 1.0291 3.033 8.140 27.15 May sicgiweevaasetneeen 11.95 1.0290 3.264 8.166 28.56 JUNC e veceeessasa sae 10.45 1.0287 3.405 8.113 29.56 JULY ssossese: cams s va 8.82 1.0283 3.458 8.027 30.11 AUBUSE 00.0... hea ee ese 9.66 1.0287 3.586 8.149 30.57 September. .......... 9.07 1.0289 3.650 8.230 30.72 October .............. 7.67 1.0292 3.434 8.247 29.39 November ............ 6.63 1.0299 3.823 8.501 31.01 December............. 5.11 1.0300 4.267 8.616 33.11 January 2............ 3.0 1.0302 5.050 8.823 36.40 January 3............ 2.7 1.0300 5.400 8.843 37.91 January 4............ 2.8 1.0299 4.720 8.680 35.22 January 6............ 2.3 1.0307 5.470 9.032 37.71 January 7........+... 2.4 1.0299 5.440 8.824 38.14 January 8............ 2.3 1.0304 5.250 8.911 37.07 January 9............ 2.3 1.0310 5.200 9.054 36.48 January 10............ 2.1 1.0308 5.090 8.980 36.17 January 11............ 2.2 1.0308 5.100 8.982 36.22 January 14............ 1.9 1.0277 6.900 8.565 44.60 January 16............ 1.3 1.0301 8.300 9.446 46.77 January 18............ 14 1.0288 7.480 8.958 45.50 many animals and extending over a long period, have proven that the morning milk does not differ from the evening milk in fat content when the period between the milkings is equally great and the feed, the amount of drinking water taken, etc., are the same. But in prac- tice this is not the case, because usually a small dif- ference exists, so that where there is a larger quantity VARIATIONS IN COW’S MILK 33 of milk there is a smaller percentage of fat. Fleisch- mann found by continuous investigations of one herd of 120 to 130 cows during one year, that on the average for the whole year the morning milk contained a little more fat than the evening milk (3.260 per cent. against 3.183 per cent.), while the quantity of morning milk was a little less than that of the evening milk (4.143 kg. against 4.616 kg.). There is a slight difference dependent upon the sea- sons; it has been shown that in the summer the morning milk contains a slight excess of fat while in the winter the evening milk is the richer. It follows that since the quality of milk is influenced by external influences, there can be no general rule to define the difference between morning and evening milk but, usually, if no other con- ditions arise, this difference is comparatively small. It is commonly believed that three milkings a day cause not only the production of a greater quantity of milk, but also a somewhat greater percentage of fat, but it can scarcely be said that there is definite proof of an increase in the percentage of fat. If the milking is done by a strange or inexperienced person, the flow is diminished. This also influences the quality of the milk. The first and the last milk drawn differ greatly in fat content. It is supposed that the fat globules adhere firmly to the walls of the ducts, as a layer of cream, and are freed from these only with dif- ficulty. The following figures show the results of analyses by de Vriezes, who found in the first streams 1.2 per cent. fat; after drawing about one-quarter the quantity of milk, 2.1 per cent. fat; after drawing about one-half the quantity of milk, 3.6 per cent. fat; after drawing about three-quarters the quantity of milk, 5.2 per cent. fat; in the last milk, 7.1 per cent. fat; in the very last drops of milk drawn, 10.0 per cent. fat. 3 34 MILK HYGIENE Therefore, by milking a single cow, one can obtain milk of the greatest variety of fat content, which must be considered when samples are taken from individual animals for the purpose of examination. According to Hittcher’s investigations, the situation seems, singularly enough, to be wholly changed if the calf is permitted to suck the cow; the milk that remains is not rich, but is much poorer in fat. Fats. Percent. Solids not fat. Per cent. Number of the eee Minimum. Maximum. . Minimum. Maximum. 1 2.621 4.698 7.859 8.771 2 2.160 3.404 7.293 8.707 4 2.163 3.965 7.702 8.743 5 2.548 3.900 7.636 8.577 6 2.096 3.446 7.753 8.893 7 2.257 3.837 7.974 8.914 8 2.690 4.117 7.943 8.897 9 2.566 4.709 8.197 10.050 10 2.464 6.000 7.728 8.939 11 2.741 4.649 8.305 9.371 12 2.509 5.505 8.582 9.550 13 2.645 4.724 8.389 9.623 14 2.097 4.173 8.394 9.131 15 2.437 4.234 8.031 9.046 16 2.326 4.637 8.040 9.363 18 2.537 4.390 8.098 9.170 The opinion expressed in recent years, that by a special method of milking the average fat percent- age of milk of individual cows may be raised, is in- correct. 6. Daily variations. Daily examinations of milk of individual cows show that not only the quantity of milk undergoes change from day to day, but, at the same VARIATIONS IN COW’S MILK 35 time, strange to say, the chemical composition of the milk is subjected to daily variations that may reach considerable extent. Knowledge of this is naturally of the greatest importance in the detection of milk adul- teration. The table on page 34 is given by Fleischmann to show the minimum and maximum fat percentages in the milk of a series of cows examined daily during an entire period of lactation. As is shown, the percentages of fat differ consider- ably even in milk from the same cow; one cow, number 12 in the table, produced milk differing in fat content as much as 100 per cent., that is, from 2.509 to 5.505 per cent. Cow No. I. Cow No. V. Cow No. VII. Cow No. VIII. 3.214 3.040 2.566 3.551 2.869 2.825 oe 3.592 2.859 3.3822 3.080 3.244 2.862 Sere 8.314 2.932 rear 3.043 2.822 2.790 3.294 3.790 2.329 3.047 3.070 2.996 2.308 iyne 2.847 3.369 2.616 . 2.816 3.685 3.272 3.334 3.199 3.749 3.189 3.381 8.732 4.031 3.267 3.402 3.620 3.927 3.068 3.316 3.522 3.792 8.795 3.344 3.492 3.844 3.470 2.970 3.633 The variations are not always gradual, but occur spasmodically, as is evident from the figures above, taken from Fleischmann’s work on milk. The numbers in the perpendicular columns give the percentage of fat for successive days; the figures above the dividing line date from the beginning of the lactation period of the cows, while below the line the figures given refer to 36 MILK HYGIENE the end of the milking period. The examples are chosen in order to make plain the daily variations with the individual animals. One may find even greater variations by examining the morning and evening milk. As examples, some re- sults are given from the daily examinations of milk from the above mentioned cows number I and number V, the figures referring alternately to the morning and the evening milk on successive days: Cow No. I. Cow No. V. MOPING sc nsiscie sain see case cenae tes cx 3.375 3.180 WNVGMING: “Place a small quantity of diphenylamin at the bottom of a porcelain dish, and add to it about 1 ¢.¢. of pure, concentrated sulphuric acid; allow a few drops of the milk serum (obtained by adding a little acetic acid to the milk and warming) to flow down the sides of ‘the dish and over the surface of the acid. If a blue color develops in the course of ten minutes, though it may be faint, it shows the presence of nitrates, after ten minutes a reddish-brown color is always developed from the action of the acid on the serum. There should be no difficulty in detecting an addition of 10 per cent. of water to the milk by this test, if the water added contained 5 parts of nitric acid, or more, per 100,000.” L. P.] c. The skimming of whole milk in conjunction with the addition of water, or the addition of skimmed milk as well as water, are common methods of adulteration. It is easily understood that the fat content is consid- erably lessened in this way, and that also the solids not fat decrease; it is evident, besides, that the percentage of solids not fat (p) is lessened and, consequently, the 58 Warrington and Woll. Testing Milk and its Products, 13th edition. Madison, 1904. DETECTION OF ADULTERATION 223 specific gravity of the solids (m) must be increased. The specific gravity of adulterated milk can vary consider- ably, often it is nearly normal, but frequently it is slightly diminished. Feser has given the following ex- ample of such adulteration: The unadulterated milk had 3.95 per cent., fat; 8.9 per cent., solids not fat; 1.031 specific gravity; by par- tial skimming, it was changed to 2.19 per cent., fat; about 8.9 per cent., solids not fat; 1.034, specific gravity; by the addition of water it was further changed to 1.21 per cent., fat; about 8 per cent., fat free solids; 1.0305, specific gravity. Decisive points for determining if such adulterations exist are the low solid contents, the low fat per cent., the almost normal specific gravity of the milk, the in- creased specific gravity of the solids (m) which, in the above example, was changed from 1.305 to 1.473, and in the low specific gravity of the whey. If nitrates are proven in the milk there is further support for the con- clusion that it is watered. When a sample of adulterated milk can fairly be compared with another which is known to be unadulter- ated (samples taken from the same dealer the same day, milk of a large herd, etc.) [or with an accepted stand- ard] one can form an opinion of the extent of the adulteration by means of a formula derived from Béohm- lander : M=2xw—W os {R E= 100 (a — M shows the quantity of water added to 100 grm. of milk; W is the per cent. of water in the unadulterated and w in the adulterated, or suspected, sample; R and r are the percentages in these two samples of solids not 224 MILK HYGIENE fat; E represents the percentages of fat removed by skimming, while F and f show the percentage of fat in the two samples. In the above case one could find by computation: M= 2 90.79 + 87.15 = 1.112 « 90.79 — 87.15 = 13.81 ms 1.21 rof. Rubert Boyce. The following is an extract: CONCLUSION “‘ We may briefly sum up the bearings of the results at vhich we have already arrived as follows: “ There. can be no doubt but that in a certain number of ase’ the tuberculosis occurring in the human subject, es- rectally in children, is the direct result of the introduction into he human body of the bacillus of bovine tuberculosis; and here also can be no doubt that in the majority at least of hese cases the bacillus is introduced through cows’ milk. lows’ milk containing bovine tubercle bacilli is clearly a cause f tuberculosis and of fatal tuberculosis in man.* “‘ Of the sixty cases of human tuberculosis investigated by is, fourteen of the viruses belonged to Group I, that is to say ontained the bovine bacillus. If, instead of taking all these ixty cases, we confine ourselves to cases of tuberculosis in rhich the bacilli were apparently introduced into the body by ray of the alimentary canal, the proportion of Group I becomes ery much larger. Of the total sixty cases investigated by us, * Original not italicized. 285 286 MILK HYGIENE twenty-eight possessed clinical histories indicating that in them the bacillus was introduced through the alimentary canal. Of these, thirteen belong to Group I. Of the nine cases in which cervical glands were studied by us three, and of the nineteen eases in which the lesions of abdominal tuberculosis were studied by us, ten belong to Group I. ‘“< These facts indicate that a very large proportion of tuber- culosis contracted by ingestion is due to tubercle bacilli of bovine source. “A very considerable amount of disease and loss of life, especially among the young, must be attributed to the consump- tion of cows’ milk containing tubercle bacilli. The presence of tubercle bacilli in cows’ milk can be detected, though with some difficulty, if the proper means be adopted, and such ought never to be used as food. There is far less difficulty in recog- nizing clinically that a cow is distinctly suffering from tuber- culosis, in which case she may be yielding tuberculosis milk. The milk coming from such a cow ought not to form part of human food, and indeed ought not to be used as food at all. “‘ Our results clearly point to the necessity of measures more stringent than those at present enforced being taken to prevent the sale or the consumption of such milk,’? INDEX. Abdominal tuberculosis, 78 Abnormal coloration, 56 odors and tastes, 55 Abortion, 41 Absorption of odors, 68, 69 Acid, benzoic, 64 boric, 62 citric, 150 lactic, 52 reaction, 227 salicylic, 63 Acid-fast bacteria, 81 Acidity, determination of, 253 Acidobutyrometer, Gerber’s, 209 Actinomycosis, 92 and tumors, 48 Addition of lactose or cane sugar, 221 Adwmixture of dirt, 126, 127 Advantages derived from pasteur- izing market milk, 138 Adulteration, frequency of, 197 of cream, 225 partly skimmed and skimmed milk, 225 Adulterations, effects of, 224 Age of the cow, 29 Albumin, 14 Aleohol test, 229 Alkalies, 68 Alkaline reaction, 227 Alkaloids, 49 Alpine cattle, milk of, 40 Amphoteric reaction, 227 Anthrax, 90 Antisepties, 61, 68 Appearance of milk, 226 Arnold’s guaiae method, 192 Arsenic, 60 Asiatie cholera, 117 Ass’s milk, 24 Attendants, health of, 178, 185 Automatic temperature-regulator, 134 287 Babcock’s method, 214 Backhaus’s infants’ milk, 151 Bacteria, acid-fast, 81 in dung of cows, 127 market milk, 122 milk, 120 microscopic estimate of, 251 of putrefaction, 61, 229 pathogenic, 129 Bacterial milk analysis, standard method for, 237 Bacteriological examinations, 231 Beast milk, 12 Beet taste, 40 Benzoic acid, 64 Bitceh’s milk, 25 Blue milk, 56 Board of Health lactometer, 203 Boiled taste, 59 Borie acid, 62 Breed peculiarities, 27 Buffalo’s milk, 23 Burnt taste, 40 Buttermilk, 191 Calf cholera, 101, 125 Carbohydrates, 18 Carbolic odor, 69 Casein, 14, 16 Catarrh, mucous, 46 purulent, 46 Cat’s milk, 25 Cell protoplasm, 14 Cells, degenerated, 13 Cellular content of milk, 247, 291 Certified milk in America, 275 Philadelphia, 267 Changes in milk, 51-58 at, high temperatures, 58, 59 the secretion, 46-48 Cholera, Asiatic, 117 ealf, 101, 125 Citric acid, 150 Cleanliness, 176 288 Colostrum, 12, 29, 30 bodies, 12 Composition of milk, 21-26 Constituents of milk, 15-21 Contamination with bacteria, 120- 126 organisms, 104-120 Control of milk in cities, 197 Contusions of the udder and teats, 45 ’ Cooler, 135 : Copenhagen Milk Supply Com pany, 159 Counting, 246 Cow, disease of, 42 Cowpox, 89 Cow’s milk, 21 Cream, 191 adulteration of, 225 Curd fermentation, 230 Daily variations, 34 Dairy farm inspector, 167, 168 Degenerated cells, 13 Determination of fat content of milk, 208 of bacteria, numerical, 238 of streptococci, 250 Digestion, 147 Dilution of whole milk with water, 219 Diphtheria, 112 bacilli, 114 Dirt, 127 Disease of the cow, 42 Effects of various adulterations, 224 of acidity, 253 Embolism and thrombosis, 45 Enteritis, 98 Examinations, bacteriological, 231 for dirt, 235 pus, 234 of cellular contents, 247 Excretion of foreign matter, 48-50 of poisonous substances with milk, 60, 61 Exercise and work, 42 INDEX. Farm conditions, 273 Fats, 19 Fatty degeneration, 14 Feeding the herd, 173 Fermentation, curd, 230 test, 229 Feser’s lactoscope, 198 Fjord pasteurizer, 132, 133 Food, influence of, 37 Foot-and-mouth disease, 87 virus of 89 Foreign matter, excretion of, 48 Formaldehyde, 66 Formalin, 66 Formol, 66 Galactase, 20 Gangrenous mastitis, 47 Gartner’s fat milk, 151 Gases, 20 gas-producing organisms, de- tection of, 251 Gerber’s acidobutyrometer, 209 German instructions for producing nursey milk, 265 Globulin, 14 Goat’s milk, 23 Half milk, 190 skimmed milk, 190 Harmful properties of milk, 60 Health of the attendants, 178 Herd, attendants of, 178 feeding the, 173 health of, 169 sample, 201 sudden changes in food of, 176 Ineubation, 246 Indigestion, 101 Individual peculiarities, 28 Infant mortality, 126 Infection by milk, 70-104 Infectious diseases, 103 Influence of food, 37 Inorganic salts, 20 Inspection of the milk, 10 Intestinal tuberculosis, 72 Todine, 60 INDEX. 289 Laetalbumin, 18 Lactation period, 29 Lactic acid, 52 Lactodensimeter, Quevenne’s, 202 Laectoglobulin, 18 Lactometer, Board of Health, 203 Lactoscope, Feser’s, 198 Lactose, 14, 18, 221 Lecithm, 150 Leffmann-Beam method, 213 Legal standards, 187, 188 Lung plague, 92 Mare’s milk, 23 Mastitis, 46, 93, 125 gangrenous, 47 parenchymatous, 47 Media, 243 Medicines, 43 Mercury, 60 : Method, Arnold’s guaiac, 192 Babcock, 214 Leffmann-Beam, 213 Soxhlet’s, 208 standard, 237 Storch’s, 192 Metritis, 125 Milk, acidity of, 228 analysis of, 237 appearance of, 226 ass’s, 24 Backhaus’s infants’, 151 bacteria in, 120 market, 122 beast, 12 bitch’s, 25 blue, 56 bottling of, 196 buffalo’s, 23 care of, 180 70.3 are ‘Milk, determination of fat con- tent of, 208 of bacteria, numerical, 238 dilution of whole with water, 219 elephant’s, 26 epidemics, 104 fat, 19 for infants, 147 Gartner’s fat, 151 glands, 12-15 goat’s, 23 half, 190 skimmed, 190 harmful properties of, 60 infection by, 70-104 inspection of, 10 keeping and selling, 184 legal standards for, 188 mare’s, 23 modified, 152 nursery, 265, 266 odor of, 226 of the Alpine cattle, 40 of the cat, 25 packing of, 185 pasteurized, 191 pasteurizing market, 138 preparations, 193 preparing for delivery, 182 public control of, 157, 158 public supervision of, 196, 226 putrid, 123 rabbit’s, 26 red, 56 regulation of production of, 164-181 regulation of sale of, 182-196 reindeer’s, 26 retailing in cities, 159 aala and Anliernwse 2f 100 290 Milk, sow’s, 25 taste of, 226 transparency of, 197 tubercle bacilli in, 73 mixed, 81 unclean or dirty, 235 variations in, 24-26 Voltmer’s mother’s, 151 voluntary control of, 163 whole, 186 woman’s, 24 yellow, 57 zebu’s, 22 Milking, method of, 31 time of, 31 Miliary tuberculosis, 73 Modified milk, 152 Mortality among children, 154 Mucous catarrh, 46 Nitrate and nitrites, 221 Nursery milk, 265, 266 Nymphomania, 41 Odor, earbolic, 69 of milk, 227 Odors, 69 abnormal, 55 absorption of, 68, 69, 70 strum, 41 Oily taste, 56 Ovariotomy, 41 Paracasein, 17 Parenchymatous mastitis, 47 Partial skimming, 218 Partly skimmed, adulteration of, 225 Pasteurization, 128-142 objections to, 139 quick, 131 Pasteurized milk, 191 Pasteurizer, Fjord, 131 Pasteurizing a fluid, 128 market milk, 138 Pathogenic bacteria, 129 Pepsin digestion, 17 Peptone, 123 Plating, 244 Potassium bichromate, 65 INDEX. Preparing for delivery, 182 Preservatives, 61-68 Preserving samples for analysis, 201 Proteids, 16 Pseudo-tubercle bacilli, 81 Public supervision, 196, 226 Purulent catarrh, 46 Putrid milk, 123 Quevenne’s lactodensimeter, 202 Rabbit’s milk, 26 Rabies, 91 Rapid method for determining acidity of milk, 228 Reaction, 227 acid, 227 alkaline, 227 amphoteric, 227 Red milk, 56 Regenerative heater, 145 neetieon of production, 164- 18 sale, 182-196 Reindeer’s milk, 26 Retailing milk in cities, 159 Sale and delivery, 182 Salicylic acid, 63 Salts, 20 Sample, herd, 201 Samples, preserving, 201 taking, 200 collection of, 239 Scarlet fever, 115 Sediment, 126 Septic metritis, 101 ea conditions, significance of, Sheep’s milk, 23 Skimmed milk, 190 ae milk, adulteration of, Skimming of whole milk in con- junction with addition of water, 222 partial, 218 Slimy milk, 124 Soapy taste, 56 INDEX. Sore throat, 119 Sour milk, 123 Sow’s milk, 25 Soxhlet’s method, 208 Specific gravity, 197 of milk and whey, 202 whey, 206 Stage of the lactation period, 29 Sterilization, 130, 143-146 Sterilized milk, 192 Storch’s method, 192 Streptococci, determination of, 250 Sudden changes in food of herd, 176 Suppurative processes, 102 Tabes mesenterica, 78 Taking samples, 200 Taste, beet, 40 boiled, 59 burnt, 40 of milk, 229 oily, 57 soapy, 57 Tastes, abnormal, 55 Temporary changes, 38 Test, aleohol, 229 fermentation, 229 Transparency of milk, 197 Toxie substances, 60 Tubercle bacilli in milk, 72 mixed milk, 81 separation of, 85 temperature at which killed, 86 Tuberculosis, 71-78 abdominal, 78 291 Tuberculosis, broncho-pneumonia, 72 in cattle, 71 intestinal, 72 noiliary, 73 udder, 48, 71 Tumors, 48 Typhoid bacillus, 110 fever, 106 ) Unelean or dirty milk, 235 Udder and teats, contusion of, 45 inflammation of (mastitis), 93 oedema, 46 tuberculosis, 48, 71 Unsanitary practices in bottling, 195, 196 Variations in cow’s milk, 26-45 Viscogen, 226 Viscosity, 58 Volatile oils, 60 Voltmer’s mother’s milk, 151 Voluntary control of milk, 163 Water, 16 supply, 179 Whey proteid, 17 specific gravity of, 202, 206 Whole milk, 186 dilution of with water, 219 skimming of in conjunction with water, 222 Woman’s milk, 24 Yellow milk, 57 Zebu’s milk, 22 f saa ‘ % Pie aS Suv Aone ; PAPE aE , £3 z ps VIP Maar oe wy, Pe Manat at i need PERSO . ’ es Pret batted EEE E fi EAA Ree ede Vor. i \ 7 2 fine aes re a Poy nyne 7, sista? ree) So fas “ mS ne ¥D S833 tas Ses Se See a > a SS se serena “a at = Seaeraneditassea utits te a ane