The bulk of the samples of condensed milk in the market are made from milk, with the addition of large quantities of cane sugar to act as a preservative. The composition is very variable, for the original milk is skimmed milk, whole milk, or milk enriched by the addition of cream. Leeds gives the composition of fifteen varieties and the mean of 41 analyses of a good brand, as :
Mean of 41 Analyses.
Original milk fat....
the average number of times condensed.....
These results show great variation in composition, but a still more serious defect is present in many samples, namely, a marked deficiency of fat in those made from skimmed milk. An analysis of seventeen samples by Bernard Dyer yielded the following percentages of fat in the various brands examined:
Marguerite . . 0.42
Tea .... 0.48
Gondola. . . 048
Cup .... 0.49
Goat. . . . 0.56
Calf .... 0.60
Wheateheaf. . 0.62
Swiss dairy . . 0.63
Daily . . . 0.69
Clipper . . . 0.73
Shamrock . . 0 .79
Cross. . . . 0.96
Home . . . 102
Handy . . . 1.49
Nutrient . . 2.36
Cow. . . . 2.84
As you like it . 4.23
Such brands as these may be useful as food, for culinary purposes, and for addition to tea, etc., but should certainly never be given for infants, unless it is temporarily advisable to omit fat from the diet.
Some of the best sweetened condensed milks are Nestle's and the Anglo-Swiss Milkmaid brand, made both in England and Switzerland. Since the amalgamation of the companies making these brands, the Milkmaid Swiss and Nestle's Swiss milks have a similar composition, differing a little from that made in England. They are prepared under most careful supervision from whole milk, which is obtained fresh from local inspected farms, under stringent regulations as to proper cooling of the milk and general cleanliness. The sugar added is the purest obtainable and is still further purified at the factory to get rid of any dirt present. All the processes of condensation and tinning are carried out in the best possible manner, and in every respect these varieties are excellent specimens of condensed milk. There are other good brands. One of them, the Peacock brand, should be mentioned, for it contains only about half the amount of cane sugar usually added. The protein, lactose and cane sugar amount to a total of 43.32 per cent (Lancet). Peacock condensed milk is made from whole milk and skimmed milk, so the two kinds must not be confused.
(S) Made in Switzerland. (E) Made in England.
Humanized condensed milk is prepared by the addition of cream and lactose, before condensation, in such quantities as to form a solution, when suitably diluted, equivalent to human milk in percentage composition.
The composition of condensed milk shows that it is a valuable article of diet. For adults and children beyond the period of infancy it is a safe and useful food, provided plenty of fat is obtained from other sources. It is, however, in its wide use as a food for infants, in the place of the maternal milk or the fresh milk of some other animal, that it causes widespread injury and deserves most serious criticism.
The analyses of the best brands show that condensed milk, in the ordinary dilutions made use of, is grossly deficient in fat. If diluted beyond one part in eight, it will also be deficient in protein and sugar, when compared with average human milk. And it is not a fresh food. It is generally much too diluted, forming a weak sugary solution, deficient in fat and protein. The weakness of the mixture is to some extent compensated by the greater quantity taken, and its easy digestibility and absorption. The digestibility is partly due to the weakness of the fluid and partly to the action of the heat on the casein, which is rendered uncoagulable by rennet. Its wide popularity among the poor is due to the ease with which the baby's meal is prepared. The milk is less liable to go sour than cows' milk which, in addition, is difficult to obtain fresh and clean. Cows' milk causes more trouble in preparing each feed, and the curd is difficult to digest and liable to set up vomiting, colic or diarrhoea. The baby usually likes the sugary fluid, takes it well, digests it, is satisfied, and grows fat. The evil effects develop slowly, as a rule, and are not recognized as due to the diet, being more readily ascribed to vaccination, the bite of a dog, or some such cause.
An infant fed on condensed milk becomes anaemic, fat and lethargic. The deficiency of protein, and the alterations produced in it by heat, lead to weakness and flabbiness from the impoverishment of the blood and impaired nutrition of the muscles. The excess of sugar causes a deposition of fat and is liable to set up intestinal derangements from fermentative changes. The deficiency of fat, in addition to other defects in the food, causes rickets. It is extremely rare for a babe fed on condensed milk not to develop some degree of rickets. Frequently the disease supervenes in a severe form. Further, the child, though large and fat, is far from strong and has little vital resistance to intercurrent disease, such as attacks of bronchitis or gastro-intestinal derangements, to which these infants are peculiarly liable. Another danger is the appearance of scurvy, for the milk is deprived of its anti-scorbutic properties by the heat used in condensing it. The alterations in the salts, due to heat, have probably a deleterious effect on metabolism and nutrition.
Although the milk is condensed at a high temperature it is not invariably sterile. Cultivation experiments have frequently demonstrated the presence of micro-organisms. It will keep remarkably well in the unopened tin, but after a time is liable to decompose. It may become slimy, cheesy, or semisolid. It may become quite solid or "go hard." It may undergo putrefaction, in which case the tin becomes "blown." Any of these changes renders it an unsuitable food, especially for babies. Needless to say, the people who commonly use it are the ones least likely to pay attention to these changes or notice any alteration in the taste or smell. Although the sweetened variety keeps better than the unsweetened, when the tin has been opened, it will decompose pretty rapidly in hot weather unless ice or a refrigerator is available. Furthermore, condensed milk is more expensive than ordinary fresh cows' milk, diluted and sweetened, if it is given in a solution of equivalent strength or in the proportions appropriate for infant feeding.
It is a valuable substitute for cows' milk when travelling, in very hot weather, and when good cows' milk is not available. In many marasmic conditions and in some affections of the alimentary tract it is also useful. Given under medical advice and as a temporary expedient, there is nothing to be said against its use. One may go further and state that it is quite possible to bring up a baby perfectly satisfactorily on condensed milk, provided that extra fat is given in the form of cod-liver oil or olive oil, extra protein in the form of egg albumin, and fruit juice to counteract the tendency to scurvy due to a prolonged diet of cooked food. I have obtained extraordinarily good results in some instances by feeding infants on one or other variety of condensed milk, when all other methods of artificial feeding have failed and a wet-nurse has not been available. Unfortunately it is the abuse of this method of feeding which has rendered condensed milk obnoxious to the medical profession. Nevertheless, it must be candidly admitted that there are many cases in which a diet of condensed milk is infinitely superior to ordinary cows' milk, notably so in hot weather, among the poorer classes, and in some cases of marasmus. The difficulties which the poor have to contend with in obtaining fresh, clean, pure milk, and in keeping it in their insanitary, stuffy, crowded tenements, often render condensed milk a much less dangerous diet for a baby than cows' milk. The nutritive value depends on the quality of the original milk, the degree of condensation, the addition of cream (if any) and the amount of cane sugar added. Of the different varieties the sweetened ones are the best for infant feeding, and only the best brands should be used. The unsweetened should only be used under medical advice. Those which are made from skimmed milk should only be given when specially ordered, but may be used as a cheap substitute for milk for adults and children who get plenty of fat and protein in other forms. The value of separated milk is not nearly sufficiently realized. It is a rich nitrogenous food and contains lactose, whether fresh or condensed, but there is practically no fat in it.