The importance of studying condensed milk is evident when we realise that we import 500,000 cwt of it into this country every year, and that among the poorer classes there is no commoner substitute for cow's milk. The condensed milks are all made from cow's milk, either whole or skimmed. It is prepared by slowly evaporating the water off the milk by moderate heat in vacuo to the consistence of honey. As a rule, the milk is only reduced to one-third of its original volume. Most brands of condensed milk have cane sugar added to help in its preservation. We have thus three types of condensed milk: -
Whole milk, condensed and unsweetened. Whole milk, condensed and sweetened. Skimmed milk, condensed and sweetened.
The following are the chief brands: Ideal, First Swiss, Peacock, Viking, Hollandia. Their composition is as follows: -
These are prepared by evaporation by heat sufficiently strong to render the milk sterile, so that no preservative materials are added. This milk is open to the same objections as the use of sterilised milk, but it is better for infants than those forms of condensed milk in which preservation is secured by the addition of too large a proportion of cane sugar. A dilution with two parts of water makes the mixture approximate more or less closely to cow's milk Further dilution and the addition of cream and sugar are necessary to make the fluid at all similar in composition to human milk.
The unsweetened milks tend to go bad quickly when opened. For this reason they should be kept in a cold place after being opened, and the smallest size of tin should be procured.
These are made from whole milk, with the addition of cane sugar to such an extent that the cane sugar added is greater than the solids of the milk - its function is to act as a preservative. The following is the composition of some of the best brands: -
On account of the large amount of sugar present in these preparations, in order to make the milk palatable a degree of dilution is required which makes it impossible for the resulting mixture to be at all like cow's milk in its proportion of protein and fat.
Humanised condensed milk is prepared by the addition of cream and lactose, before condensation, in such quantities as to form a solution when suitably dilute equivalent to human milk in percentage composition.
The chief characteristic of the condensed separated milks is its poverty in fat - as a rule, not exceeding 1-5 per cent. When suitably diluted these milks are very deficient both in protein and fat, and are thus foods not well adapted for infant feeding. Such brands may be useful as food for culinary purposes and for addition to tea, but should certainly never be given to infants.
Condensed milks are more easily digested than cow's milk, due to the fact that in the process of preparation the casein is altered in some way unfavourable to the development of a hard curd. For this reason, condensed milk is occasionally of much value in the treatment of infants who are unable to digest ordinary milk. The great popularity of condensed milk is chiefly due to the ease with which the infant's meal is prepared. The disadvantages are marked. They contain, as a rule, too little fat. The unsweetened milks are alone satisfactory in this respect. In suitable cases this can be remedied by the addition of cod-liver oil to the diet. In the dilution recommended they are usually deficient in protein, this holds good very specially for the skimmed milk preparation. This deficiency may be remedied by the administration of protein in other forms, e.g. egg albumin. Further, they are not fresh foods. They all lack the important "antiscorbutic" element present in fresh milk. This can to some extent be counteracted by adding to the dietary a little fruit juice every second day. The nutritive value of any preparation depends on the quality of the milk, the degree of condensation, the addition of cream (if any), and the amount of cane sugar added. It need hardly be added that only the best brands should be used. It should also be noted that condensed milks are expensive in comparison with ordinary milk. As a rough computation, it may be said that the price of the milk diluted and ready for use works out at 4d. per pint.