SESSION 5. THE USE OF EVAPORATED, CONDENSED, AND DRIED MILK IN THE DIETARY.

Chairman, Dr. MARY S. ROSE, professor of nutrition, Teachers' College, Columbia University.

Secretary, Miss JESSIE M. HOOVER, specialist in milk utilization, Dairy Division, United States Department of Agriculture.

FIRST BAPTIST CHURCH AUDITORIUM,

Syracuse, N. Y., Friday, October 5, 1923-1.30 p. m. Chairman ROSE. In spite of many difficulties in getting our program under way, it seems possible for us now to open the session devoted to the use of evaporated, condensed, and dried milk in the dietary.

Being interested in nutrition, nothing seems to me of any greater importance than the consideration of the ways in which we can make a food so fundamental as milk available to people under all sorts of circumstances. Surely this discussion of the ways milk which has been preserved can function in nutrition is a very important aspect of the whole question of the world's use of milk.

The first paper we have on our program this afternoon is, "The development of dried milk as a food, " by Dr. R. J. Blackham, formerly in the British medical service in India. Doctor Blackham is not present, and our permanent secretary has not yet come in, so that I do not know whether he will be represented or not. We will place that paper at the end of the program and go on to the next subject The use of sweetened condensed, evaporated, and powdered milks for feeding infants in the Tropics," by Dr. W. E. Deeks, who is in charge of the medical department of the United Fruit Co. and who has had considerable experience in the feeding of infants in the Tropics. [Applause.]

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THE USE OF SWEETENED CONDENSED, EVAPORATED, AND POWDERED MILKS FOR FEEDING INFANTS IN THE TROPICS. WILLIAM E. DEEKS, M. A., M. D., general manager, medical department, United Fruit Co., New York City.

Some women cease to lactate shortly after their infants are born, while others lactate insufficiently to nourish their babies during the nursing period. This is particularly true in the Tropics where all metabolic activities are lessened. Other methods of feeding the babies must therefore be sought.

Wet nursing has been employed, but it is only an occasional mother who has sufficient milk to nourish her own child and to provide an extra supply for another. Furthermore, the possibility of contracting a constitutional disease from a potential wet nurse discourages one from resorting to this measure unless other adequate sources are not available.

PREPARED INFANT FOODS.

Almost all of the infant foods on the market, of which there are a great many brands, are disproportionately large in carbohydrates and deficient in fats. Some are deficient also in proteins.

The carbohydrates are derived largely from cereals. Many of these brands contain raw or partially cooked starch which infants are unable to utilize. In the Tropics particularly it was found that the few babies which were able to assimilate prepared infant's food were fat but did not have the energy of a normal child. Excess of carbohydrates leads to a train of characteristic symptoms. Such children are fretful and irritable, with dry lusterless hair, and are subject to intestinal disturbances followed by diarrhea. They are prone to eczema, rheumatism, recurring bronchitis, frequent urination, pustular dermatitis, and other skin irritations. In general, it may be said that this class of prepared foods for infant feeding in the Tropics is a failure.

COMPOSITION OF MILK.

Milk is composed of protein, fats, carbohydrates, mineral salts, and vitamins, and each element plays a definite rôle in the nutrition and development of the child.

Protein. This occurs in the form of casein, lactalbumin, and nitrogen-bearing extractives of unknown composition, but for the purpose of this paper they will all be grouped together. Protein, with the mineral contents of the milk, is necessary for the building up of new and the repair of waste tissue. Animals which grow rapidly produce milk much richer in these elements than those which grow more slowly. This is very well illustrated in Table 1 (Robert Hutchison) in which is shown the amount of protein, ash, lime, and phosphoric acid present in the milk of some of the domestic animals, and the length of time it takes to double their respective weights:

If protein is taken in excess it is prone to produce digestive disturbances, with diarrhea, and undigested curds appear in the stools. This is aggravated when excessive gastric acidity is present.

Butterfat. This is another important element in the composition of milk. It is absolutely necessary, not only for the production of heat and energy (muscular and nervous), but also because the fat soluble vitamin A is associated with it. It is interesting to note that the fat contents vary extremely in different animals. In human milk it ranges from 3 to 4 per cent, whereas in the milk of the whale and walrus, whose young live in the cold Arctic waters, the fat content of the milk is from 40 to 43 per cent. The heat value of fat is two and one-quarter times greater than that of the same weight of a pure protein or carbohydrate.

Carbohydrates.-This in milk is in the form of lactose or milk sugar, and it serves the purpose of producing heat and energy.

Mineral salts.-Milk is rich in mineral salts (except iron), particularly salts of potassium and the phosphates of sodium and calcium, which are necessary for the building up of tissue and bone. When taken in excess they apparently do no harm, as the system will assimilate what is necessary and discard the balance.

Vitamins. Up to the present, four vitamins are known, which have been designated vitamins A, B, C, and D. These are powerfully active substances and essential food factors in the processes of growth and the maintenance of health. They are necessary for the proper functioning of the glandular structures concerned in digestion, and also of all of the ductless glands which play such an important rôle in the life processes. Their exact composition is unknown, but their deficiency in the diet leads to serious health conditions; in fact, it has been said that food without vitamins is dead. Human milk, like the milk of other animals, varies extremely in composition. The race, class of food, period of lactation, hygienic surroundings, and individual idiosyncrasies are all modifying factors in the nursing mothers. Table 2 (Robert Hutchison) shows the variation in composition in human milk and cow's milk. It will be noted further that the chemical reaction of human milk is alkaline, and that of cow's milk is acid:

Any successful method for the feeding of infants must have as a basis some form of milk which must approximate in composition human milk. When human milk is not available, other sources of fresh milk are the cow, goat, mare, and burro, but there are objections to the use of the fresh milk of each of these animals in the Tropics. Table 3 (Robert Hutchinson) shows the average composition of their milk, also of human milk.

It will be noted from this table that the milk of the burro approximates the composition of human milk nearer than the others, but it is deficient in fat. The writer has seen children successfully reared by the use of burro's milk. In one case the infant was born

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at the seventh month of gestation and was successfully reared by the use of burro's milk. The burro was kept in the yard, and when the infant required feeding the udder of the animal was washed, then sufficient milk was withdrawn and transferred to the feeding bottle. Few families are in a position to resort to this method of feeding, and there is an objectionable feature in the presence of a burro with its young in your yard night and day. The same difficulties are met with in the use of mare's milk. It is also deficient in fat, and, moreover, there is not sufficient of it available to meet the requirements of the many infants born in the Tropics whose mothers are unable to nurse them.

A great many people in the Tropics owe their lives to the use of goat's milk. Goats are hardy, easily fed, and thoroughly domesticated, and in country districts, where pastures are available, a bountiful supply of milk is readily obtained. Few children, however, are able to assimilate it without modification, and in this respect it resembles cow's milk.

There are also many difficulties encountered with the use of fresh cow's milk. The quality of the grass in the Tropics does not supply a good grade of milk, and to make it satisfactory the animals must be specially fed. Cattle food, as a rule, is expensive and difficult to obtain, and the improved quality and quantity of the milk does not reward one adequately to justify the extra expense. Moreover, the people in most of the tropical countries are not yet sufficiently educated to enable them to realize the necessity of cleanliness in milking, nor do they appreciate the need for proper care of the milk, particularly if it has to be transported to any distance. The continual warm climate favors bacterial growth with consequent changes in the milk. Milk is prone to the invasion of three different types of bacteria: (a) The acidophilic group, which grows vigorously and rapidly converts lactose into lactic acid with a consequent souring of the milk; (b) the second group (the growth of which is not as vigorous as the first, and is inhibited by its presence), which decomposes the proteins, causing putrefaction in milk; and (c) the third group, which consists of the pathogenic bacteria causing typhoid, cholera, diphtheria, scarlet fever, dysenLery, etc. These are accidental infections which may contaminate milk and thereby transmit them to man.

The pasteurization of milk, by maintaining a temperature of approximately 160° F. for 20 to 30 minutes, destroys the germs of the third group and all but the spores of the first two groups. When milk is boiled it is said to be sterilized, and practically all germs are destroyed by this process. In the Tropics it is better to boil the milk rather than attempt to pasteurize it. Boiled milk is just as digestible as fresh milk, if not more so. Some claim that the protein in boiled milk is more digestible than that in unboiled milk, as it clots more slowly in the stomach under the influence of rennin and the clot is not so firm. The taste of boiled milk is objectionable to some people, but aeration tends to correct this.

In many districts in the Tropics none of these methods are generally practicable. Therefore, the best available source in all districts for the feeding of infants is sweetened condensed, evaporated, and powdered milks.

In the early days of the American occupation of the Canal Zone great difficulties were experienced in finding a suitable food for the feeding of infants, and the only reliable sources were the sweetened condensed and evaporated milks. Those obtainable in the market were analyzed, and the results showed that they fell into three different groups. The sweetened condensed milks were found to contain from 7.66 to 11.71 per cent of protein, from 9.56 to 10.75 per cent of fats, and from 40.80 to 43.68 per cent of sugars in the form of lactose and saccharose. In other words, they were ordinary milks condensed to 35 or 40 per cent of their volume, with the addition of 40 to 44 per cent of saccharose.

The analysis of the second group (the evaporated milks) showed that they were cow's milk of average composition reduced to about 40 per cent of their volume, and contained protein, 9.67 per cent; fats, 10.14 per cent; and lactose, 12.08 per cent.

The third group (also consisting of evaporated milks) showed about the same degree of condensation as the second group, but the fat had first been removed. In consequence this group was useless for the purpose of artificial feeding of infants. An attempt was made, therefore, to utilize sweetened condensed and evaporated milks in the preparation of a formula approximating the composition of human milk.

Any formula, to be satisfactory, must have (1) the approximate composition of human milk; (2) the material must be sterile; and (3) the method of preparation must be simple in character, in order to be practical. Before discussing the formulæ, it should be premised that the digestive organs of the infant at birth are incompletely developed, but are very adaptable to changes in food, provided these changes are gradual. For that reason, during the first week of the infant's life the formula should be very weak, and at intervals its strength can be progressively increased up to a certain limit. the child grows older its increased requirements are met by increased quantities and not by increased strength in the milk. fact, human milk slowly deteriorates in food value during the first year, and the increased demands of the infant are met by increased production.

To meet the requirements, the following formula was devised:

TABLE 4.-Formula "A."

[Made from sweetened condensed and evaporated milk.]

As

In