Milk (1)

MILK 1 (in %) Cow's milk casein (in %) 10.95 2.85 1.3 8.8 2.8 1.0 4.6 1.2 0 11.0 3.1 7.0 10.5 3.2 1.2 4.5 1.5 0 is high: they alone fully cover the growing organism's requirement for proteins. Whether human milk contains any other protein bodies is still not entirely clear. In 1888, Wróblewski discovered a protein body which he named opalisin. The independent nature of this body has still not been definitively established. II. M i l k f a t. The amount of milk fat fluctuates within very significant limits: on the basis of a single study of individual portions of milk, one could only come to the conclusion that on average the percentage of fat in human milk is somewhat higher than in cow's milk. Changes in human milk (in the sense of fat content) during the course of the same feeding have served as the subject of research by many pediatricians (Gregor, Reyher, and others). By means of fractionated milk research, Reyher and others established that the first portions contain significantly less fat (1-3%) than the last ones (6-10%). In individual cases, the fat content was even higher. These data were also fully confirmed by all subsequent researchers. These studies furthermore made it possible to establish that the fat content in various portions of human milk taken during the course of a child's breastfeeding gives an almost rectilinear rise in the curve, and that if one investigates the first and last portions of milk and takes the average value, one can obtain a fairly correct idea of the fat content in human milk. i. When investigating the percentage of fat in individual portions of milk in a number of wet nurses, it turned out that it is very difficult to speak of any regularity in the change of this percentage. The different fat content in individual portions of human milk is also not explained by the various quantities of expressed milk, because experience shows that the same quantities of milk expressed by the same woman at various hours of the day contain different amounts of fat (7.5-3.3%; 1.8-4.3%; 4.1-5.2%, etc.). Investigation of daily quantities of human milk for fat content showed that the amount of fat contained in the daily portion of milk is a fairly constant and characteristic value for each individual woman. There are women who produce milk with a higher and lower fat content; on average, however, human milk contains about 4% fat. Throughout lactation, the fat content in human milk remains more or less constant. Qualitative features of human milk fat. It is striking that fat is contained in human milk in the form of a very fine emulsion. Human milk contains a significantly greater number of fat droplets in 1 mm³ than the milk of other animals. Human milk fat contains 1.4% volatile fatty acids, 1.9% water-soluble acids, 49% unsaturated fatty acids. The most characteristic feature of human milk fat compared to cow's milk fat is the insignificant content of volatile fatty acids—1.4-1.5%; cow's milk fat contains 25.3% of them. Other physical and chemical features are given in Table 21. Table 21. [...]

Melting point -30-34°, solidification point -19-22°, specific gravity at 15° - 0.97. - From a number of observations it is apparent that the properties of human milk fat depend on the mother's nutrition. It was possible to establish that goose fat, linseed oil, sesame oil, palmin, margarine pass into the mother's milk and change its physical properties [changes in the iodine number (Engel, Merkel, and others) are usually cited in the literature]. III. Milk sugar. The milk sugar content in human milk fluctuates within not such sharp limits as fat. The vast majority of researchers indicate that the sugar content in human milk is approximately 7% with minor deviations in one direction or the other (Table 22). Throughout lactation, the percentage of sugar in human milk essentially remains constant; perhaps only in the first days after birth is it somewhat lowered (5-6% instead of 6.5-7%). - Mineral constituents of human milk. The average salt content in human milk is usually considered to be 0.21%. These data, first published by Heubner and Hoffmann as early as 1894, are confirmed by subsequent researchers who cite data ranging from 0.17% to 0.24% (Pfeiffer, Lehmann, Adriance, Guiraud, and others). The works of Kamerer and Söldner, Pfeiffer, and others, who investigated the salt content of human milk during various periods of lactation, showed that the amount of salts falls throughout the entire lactation period, sometimes reaching 0.15-0.16% as early as the 4th-6th, and more often the 6th-8th month of lactation. Table 23. [...]

Among the mineral salts, human milk includes salts of Fe, Na, K, Ca, Mg, P, O, and S. - Exhaustive data regarding the content of various salts in various periods of lactation were obtained by Abderhalden. From his data it follows that during lactation, the amounts of iron, sodium, chlorine, and partly also phosphorus decrease most sharply; potassium and calcium turn out to be more stable, and the amount of magnesium changes almost not at all. The question of the form in which phosphorus is contained in human milk must still be considered not entirely clarified; until recently, the opinion was widespread that the phosphorus of human milk is bound only organically, whereas in cow's milk half of all phosphorus is bound to inorganic compounds. Of the organic phosphorus compounds, particularly great importance was attached to lecithin. At present it is known that human milk contains more lecithin than cow's milk, but this difference is not particularly great; it should also be borne in mind that fresh human milk contains more lecithin than sterilized or boiled milk. Glikin found in human milk obtained from 8 wet nurses 0.13294% lecithin, whereas in cow's milk the lecithin content was 0.0516 and resp. 0.1173%. Stoklasa's data for human milk are 0.170-0.186%, for cow's milk - 0.09-0.113% lecithin. It may be, however, that the different data of various authors are explained by unequal research methodology. Human milk contains...

as well as sulfur in the amount of 59 mg%; of these, 8-26% in the form of neutral sulfur (Bosio). In addition to all the enumerated constituents, human milk, according to Scheibe, contains on average 0.05% citric acid (ranging from 0.033% to 0.125%), which appears only on the 3rd to 4th day after childbirth. - Dry residue. Corresponding to those fluctuations that are observed in terms of the content of fat, milk sugar, and nitrogen, the dry residue of human milk also fluctuates within fairly significant limits. Pfeiffer gives figures from 8.23 to 15.56; Edraines from 9.19 to 15.31; Kammerer and Söldner from 9.41 to 14.11. If one proceeds from those average figures that were given for the percentage content of fat, milk sugar, nitrogen, and salts, it will turn out that human milk contains 11.79% dry residue. Indeed, Pfeiffer, Lehmann, Elsdon, Kammerer, and Söldner give figures ranging from 11.7% to 11.95%; other researchers give slightly more than 12%; only in the rarest of cases are indications met that human milk contains more than 13% (Guiraud - 13.16%) dry residue. Practically, it can be considered that human milk contains on average 12% dry residue. Throughout lactation, no regular changes whatsoever in terms of the dry residue content can be detected. Water. Naturally, all those fluctuations that are observed in terms of the content of certain solid constituents of human milk also affect the water content in it. If one proceeds from the fact that human milk contains 12% dry residue, then the water content in it equals 88%. - The average composition of human milk is as follows: protein - 1.0%; fats - 4.0%; sugar - 7%; salts - 0.21% (dry residue - 12%, water - 88%): furthermore, one must always keep in mind the individual fluctuations that are observed in the composition of human milk, and the fact that throughout lactation there is a certain decrease in proteins and salts, while the fat and sugar content remains more or less constant. - Caloric value of human milk. If one uses the above-given average data, then human milk contains 687.4 calories per 1 liter. Naturally, however, the caloric value of human milk varies depending on its composition. Schlossmann gives a minimum of 565.5 cal. per 1 liter at 1.8% fat and a maximum of 876.8 cal. at 5.2% fat; Sommerfeld gives figures ranging from 629.6 to 750.87 cal., but again one must constantly keep in mind those sharp fluctuations to which the composition of human milk is subject. Enzymes of human milk partially come from the blood, partially are contained in the formed elements of milk itself, especially leukocytes; in addition, enzymes can be a product of bacterial activity. It is extremely difficult to indicate the source of origin of each enzyme individually. The physiological significance of the enzymes is not elucidated in all details; finally, there is still no certainty that we know all the enzymes contained in human milk. - Catalase. Human milk, when compared with cow's milk, contains a fairly significant amount of catalase. There is more catalase in colostrum than in mature milk; this is explained by the catalase content in leukocytes; bacterial contamination also increases the amount of this enzyme. Upon centrifugation, catalase passes into the fat. Boiling destroys it. - The presence of oxidase in human milk remains unproven to this day. Mention must also be made here of peroxidase, which is contained in human milk in very insignificant quantities. Temperatures above 72° destroy this enzyme as well. Peroxidase is contained chiefly in the leukocytes of human milk; this explains its large quantities in colostrum. - Reductase and aldehyde-reductase are products of bacterial activity and therefore in fresh human milk, which contains few bacteria, they are present only in the form of traces. Upon heating to 80°, the test for these enzymes becomes negative, so that it can be used to judge the amount of bacteria in human milk and to distinguish raw and boiled human milk. - Amylase is contained in a significant amount in colostrum, and in a somewhat smaller amount in mature human milk. The addition of hydrogen peroxide increases the activity of this enzyme. The amount of amylase in human milk many times exceeds the amount of it in other types of milk (see above). - Lipase is contained in human milk in a significant amount. Upon boiling, this enzyme is destroyed. - Human milk also contains salolase - an enzyme that splits salol; cow's milk does not contain this enzyme. Finally, human milk contains a peculiar enzyme that causes the clotting of punctate obtained in hydrocele of the testis; cow's milk contains little of this enzyme.

Vitamins. With proper nutrition, human milk contains fairly significant amounts of factor A, comparatively insignificant amounts of factors B and C, and very insignificant amounts of factor D. The question of the presence of factor E in human milk has not been studied to this day. Even under unfavorable maternal nutritional conditions, cases of keratomalacia and scurvy on natural feeding are practically never observed, so that the question of increasing the amount of corresponding vitamins in human milk is usually not even raised. There are, however, data from which it seemingly follows that food rich in vitamin C increases the amount of this factor in human milk as well. The situation with factor B is somewhat different. It is known that children of mothers suffering from beriberi are themselves afflicted with this disease, so it is necessary that the mother's food contains sufficient amounts of the corresponding factor. As for the antirachitic factor D, in view of the frequency of rickets in infants, attempts were made to increase the amount of this vitamin in human milk by irradiating the mother with ultraviolet rays or giving ergosterol internally. The leading expert on this question, A. F. Hess, believes that these measures do not lead to the goal. Along with this, experimental data have been published from which it appears that enhanced administration of factor D to pregnant animals at least partially prevents the appearance of rickets in the offspring (Eufinger et al.). The influence of nutrition on the composition of human milk has been studied extremely insufficiently to this day. Some believe that the amount of mammary gland secretion depends to a very insignificant degree on the nature of the nursing mother's nutrition. Observations made during the last World War did not allow coming to any definite conclusion. As for the qualitative composition of human milk, Momm and Kramer assert that even during malnutrition, the average composition of human milk does not undergo significant changes. Contrary to this, Klotz, Lederer, and others had the opportunity to establish during the last war that the milk of poorly nourished mothers contained very insignificant amounts of fat and a reduced amount of sugar; 1 liter of such milk contained only 500-600 calories. Long before this, as early as 1877, it was noted in the Moscow Foundling Home that inadequate nutrition worsens the composition of milk. On this basis, some researchers conclude that enhanced administration of fats significantly increases the fat content in human milk (Epstein, Moll, and others). Engel and Aurnhammer do not agree with this; they assert that the mammary gland over the course of the day produces only a definite amount of fat, completely independently of the amount of secreted milk; in other words, Engel and Aurnhammer believe that the fat content in human milk is inversely proportional to the amount of milk. On the question of the influence of nutrition on the composition of human milk, Finizio published interesting data: the milk of 50 poorly nourished women had the following average composition: 0.77% protein, 2.4% fat, 5.86% sugar, 0.17% salts; after enhanced nutrition for a month, the milk of these same women contained on average 1.04% protein, 3.1% fat, 6.07% sugar, 0.21% salts. To influence the content of sugar (Lust), chlorine, calcium, and iron in human

milk of various animals (according to Raudnitz). Woman Water... Dry residue... Heat of combustion per 1 g of ash-free dry residue (in calories)... Caloric value per 1 l... Fat (in daily amount)... Specific gravity at 15°... Refractive index at 15°... Melting point... Solidification point... Heat of combustion 1 g (in cal.)... Iodine number... Saponification number... Reichert-Meissl number... Polenske number... Percentage of volatile fatty acids... Percentage of non-volatile fatty acids... Percentage of oleic acid... Cholesterol... Total nitrogen

.............. Protein nitrogen............... Casein nitrogen............. Extractive substances......... Casein................... Lactalbumin and globulin........ Urea.................. Ammonia(?) ................ Milk anhydride ............ Citric acid............... Color of lactochrome in native serum. Enzymes Catalase.................. Aldehyde catalase ............. Aldehydase ................ Peroxidase ................ Amylase.................. Glycolytic ferment........... Lipase................... Salolase .................. Proteolytic ferment.......... Fibrin ferment, tested on punctate in hydrocele of the testis ......... 87.0 13.0 5.493-5.878 736-790 5.0 0.97 1.47 30-34° 19-22.5° 9.392 32-58 218 2.5 89 1.4 49 50 0.6 0.15-0.30 0.12-0.17 0.097 0.03 0.6-1.0 0.5 0.05 0.0003 6.4 0.005-0.07 red ++ small very little + ? 5-7 + + Salts (°/₀₀)...... K₂O ......... Na₂O......... CaO.......... Including dissolved MgO.......... Fe₂O₃ ......... P₂O₅ ......... Organic P₂O₅ . Inorganic P₂O₆ ......... Cl........... Gases in volume percent CO₂ » » » O » » » . N » » » . Specific gravity at 15°..... 1.4-2.8 0.8 0.2 0.3 0.17 0.06 0.005 0.46 0.09 0.37 0.43 7.0-7.5 2.3-2.9 1-1.4 3.4-3.8 1.032 Cow 88.0 12.0 5.959 673 4.8 0.86 1.4473(37°) 30-35° 31° 9.318-62 26-49(33-36) 213-227 85-91(87) 54-60 0.5 4.4 0.12-0.2 yellow + + + + + ? 2-3 0 + small 7.0 1.7 0.5 2.0 0.6-0.6 0.2 0.01 2.4 0.6 1.8 1.0 0.51 4.2-8.6 3-7 0.1-1.0 2—3 1.028-1.034 Goat Ass 87.0 13.0 5.9 3.4 0.93 1.4627 31-34.6° 25-30° 9.241 21-35 226-242 91.0 9.0 5.3 427-490 1.0 15-17.5° 10° 9.227 9.0 0.55 0.564 0.5 0.43 0.45 - 0.05 - 3.0 3.8 0.3 1.2 0.01 - 2.5 0.1-0.15 + small small + + ? 0 + 0.39 0.24 0.6-1.8 0.3-0.7 0.1 + small very little small ? + + 1.7 1.3 0.6 1.9 0.15 0.03 2.8 0.7 2.1 1.0 10.0 0.81 0.3 1.0 0.13 0.01 1.5 0.26 1.24 0.31 1.0267-1.038 1.020 1.034 Freezing point............. from -0.5° to -0.63° Resistance in ohms Electrical conductivity 10^-5 ......... Internal friction at 15°........ Reaction to litmus ............ Ability to bind alkalis per 1 l in cm³ n/₁₀ NaOH.............. Ability to bind acids per 1 l in cm³ n/₁₀ HCl (indicator - blue lacmoid). 175-666 15-57(23) 1.41-2.56 alkaline 20-25 from -0.54° to -0.59° 180-304 32-55(44) 1.67-2.2 amphoteric 320-550 -0.57° 146 68 2.01-2.15 amphoteric alkaline 60-70 by intensified introduction into the mother's food was not achieved, so that this question must still be considered unclear. The passage of medicinal substances into human milk has been proven for iodine, salicylic acid, ether, mercury, antipyrine, aspirin, arsenic, bromine, atropine, quinine, and many other substances. In all these cases, only the most insignificant amounts of the medicinal substance can be detected in human milk, so that the influence of these agents on the child cannot be of great practical importance. It is therefore not surprising that the proposal to treat syphilis in infants by giving the mother salvarsan and arsenic rather quickly disappeared from the pages of the pediatric press. Alcohol passes into milk in an amount of 0.2-0.6% of the amount drunk, so that in some cases the alcohol content in human milk may be 5-6%. Microscopy of human milk. Under high magnification, characteristic milk corpuscles are found in human milk, the size of which ranges from 0.9 to 22 µ. On the basis of these corpuscles, it is essentially impossible to draw any conclusions about the quality of the milk. Mature milk contains a very insignificant number of leukocytes and a somewhat larger number of so-called crescents (see Colostrum). Bacteriology of human milk. The milk of healthy women contains a very insignificant number of microorganisms, which enter it from the outside, in particular from the external integuments of the mammary gland. Most often, Staphylococcus pyogenes aureus or albus is found. These microbes have no practical importance, and only Moro assumes that they may be the cause of acute disorders in infants. In diseases of the mammary gland, bacteria can pass into human milk in significant quantities. In infectious diseases, the passage of certain microbes into the mother's milk is a great rarity. In exceptionally rare cases, the pale spirochete was found in the milk of syphilitic women; isolated cases are described in which human milk contained Eberth's bacilli in the presence of the corresponding disease in the mother. Tubercle bacilli in human milk were found in cases of tuberculous lesions of the mammary glands, and also sometimes in the milk of a tuberculous mother. The passage of bacteria into human milk is apparently observed only in the most severe general diseases (of bacterial origin), but until now extremely few such cases have been published. Biological features of human milk. The passage of antibodies into milk was proven by Ehrlich as early as 1892; this passage is observed both during active and passive (although to a lesser extent) immunization of the mother. Antibodies in human milk are bound with albumins and globulins. Salge discovered diphtheria antitoxin in human milk. In typhoid and paratyphoid B, the corresponding agglutinins were also found in human milk. Along with this, human milk also contains isoagglutinins corresponding in 78% to the isoagglutinins of the mother's blood. In syphilis, the Wassermann reaction in milk often gives a positive result, which proves the presence of specific complement. The passage of opsonins into human milk must also be considered proven. The passage of toxins into human milk cannot yet be considered definitively established, but theoretically it is very probable. Difference of human milk from cow's and goat's milk: 1) according to Moro: to 5 cm³ of milk are added 2 drops of a 1°/_oo-ao^go solution of neutral red prepared in a 0.85% NaCl solution; cow's milk gives a red-violet coloration, fresh human milk gives a yellow coloration; goat's milk gives a coloration similar to cow's milk; 2) according to Umikov: to 50 cm³ of milk are added 2.5 cm³ of a 10% ammonia solution and heated for 15 minutes; human milk gives a red-violet coloration, cow's milk gives a yellow coloration, and goat's milk remains white. Falsification of human milk with cow's milk: to 1 cm³ of the milk under test are added 1 cm³ of H₂SO₄, made up to 10 cm³ with distilled water, shaken, and left to stand at room temperature for 4-5 hours. Unadulterated milk gives no sediment, whereas the casein of cow's milk (regardless of whether it is raw or boiled) in the presence of sulfuric acid gives coarse flakes. This reaction detects up to 10% admixture of cow's milk. See also Lactation, Colostrum, Digestion in Infants.