Sterilizing

Milk kept a few days may be perfectly sweet - that is, unsoured - but it has a different taste and appearance and shows a tendency to separate into serum and the more solid portions, which tend to sink to the bottom of the vessel. This change in taste and emulsification is due to the death of the white blood corpuscle-like bodies contained in the milk.

There is reason for supposing that when fresh milk is ingested, the living cells are at once absorbed without any process of digestion, and enter the blood stream, and are utilised in building up the tissues. The casein, or cheese, of the milk is digested in the usual way by the gastric juice.

The chemical result of boiling milk is to kill all the living cells, and to coagulate all the albuminoid constituents. Milk after boiling is thicker than it was before.

The physical results are that all the constituents of the milk must be digested before it can be absorbed into the system; therefore there is a distinct loss of utility in the milk, because the living cells of fresh milk do not enter into the circulation direct as living protoplasm, and build up the tissues direct, as they would do in fresh unboiled milk.

Impoverishes Milk

Infants do better on unboiled than on boiled cow's milk, provided it be sterile. For nutritive value, unquestionably, milk is best drawn by clean hands, from clean and healthy animals, into sterilized bottles, and it need not be further treated, except under special conditions. Milk must be specially clean and pure for infants in hot weather; this ideal is more or less difficult to attain, so that to be absolutely sure of this, it is safest to sterilize it by raising the temperature to 160° or 170° F., and keeping it at this point for twenty to thirty minutes.

Milk Sterilizing

Cathcart Sterilizer

One of the simplest and best means for sterilizing milk is with an apparatus more or less like the accompanying figure. This sterilizer consists of a tin can 6 inches deep, 6 inches broad at the top, 5 inches broad at the bottom, and rests on three low studs, or feet. It is provided with a nickel-plated top, soldered in just above the bottom, and it has two stout handles attached at each side. The lid fits on to an inner rim, so as to ensure that the outer surfaces of the lid and can are fresh; over this juncture an india rubber band (r) is slipped to ensure against the entrance of air. In the centre of the lid is a funnel-shaped aperture 3/4 inches in dia-meter. The "stirrer" is a rectangular piece of tin bent into the form of a ship's screw, with a long tinned wire handle, which rests below in a depression in the bottom of the can, and projects above through the aperture. It is used as follows : the quantity of food, which may be a mixture of cream, milk, milk sugar and water, or even milk diluted, or undiluted, with water, required for twenty-four hours, usually three or four pints or less, is poured into it, and the lid pressed on with the stirrer in position. The sterilizer is then put into a pot, one quarter full of hot water. It is kept in this pot of boiling water for about twenty minutes with occasional agitation. The sterilizer is then removed, the broad rubber band is slipped over the junction of lid and can, and pure clean absorbent cotton packed around the projecting end of the stirrer to prevent the entrance of germs, as the milk is withdrawn from time to time from the sterilizer (a temperature of 160° to 170° F. is the ideal one for sterilizing). The temperature of the hot water bath as above described is about 206° F. This could be attained by using water somewhat short of boiling water.

The sterilizer requires to be put in a cool place. Before each feeding the mixture is agitated by the stirrer, and the quantity required drawn off into the feeding bottle, in which it is warmed by placing it in hot water. The sterilizer may be used for milk, cream, or for the modified-milk mixture, and is capable of holding about four pints. A sterilizer capable of holding about a quart is sufficiently large for a small family. For home made purposes, where no sterilizing apparatus is at hand, an extemporaneous sterilizer can easily be made from good stout bottles, or jars.

Modified Cow's Milk

After sterilising the milk the next step is to separate the milk and cream and then re-combine them in the same proportions as are found in human milk. The top of the milk, or cream, may be taken off after it has stood for ten or twelve hours in the refrigerator, or other cool place. Average cream contains ten per cent. fat. Assuming this as an average, the following formulas for milk modification for artificial infant feeding are recommended: -

For feeding infants, one week old, first week : sterilized cream, two ounces, or four tablespoonsful; fat-free or skimmed milk, the same amount; lime-water, one ounce, or two tablespoonsful; water, fifteen ounces; seven even teaspoonsful, or seven drams, of milk sugar. Dissolve the sugar of milk in the fifteen ounces of sterilized or clean water. Mix the milk, cream, and water with the sugar of milk. Divide half of this mixture into ten bottles, two tablespoonsful in each, equivalent to one ounce, thus making the ten meals required for a day till the baby is a week old, feeding once in two hours during the day, and once in the night between 9 p.m. and 5 a.m.