Pasteurised Milk

Pasteurised milk is similarly prepared to sterilised milk, and is, in fact, sterile, but the temperature is only raised for twenty minutes to 1670 F., instead of the boiling point, 2120 F. It is somewhat more easily digested than sterilised milk, but it does not keep so long and spoils in one or two days. It has the advantage of tasting more like fresh milk.

PLATE 1.

Care of Modifying Materials.

Care of Modifying Materials.

Aseptic Precautions.

Aseptic Precautions.

Milk Room and Coolers for modifying materials.

Milk Room and Coolers for modifying materials.

Special Sterilizers for returned packages.

MILK LABORATORY (INTERIOR). (From Paediatrics, by T. M. Rotch, M. D).

Cleansing Milk Bottles

Both sterilised and Pasteurised milk should be warmed by placing the milk bottles in warm water without opening them. If the bottles are to be used again they should be rinsed and left standing full of water to which one or two teaspoon-fuls of borax or soda have been added. Before filling with milk they should be washed with a fresh swab and hot soapsuds, rinsed again with boiled water, and kept for at least twenty minutes in boiling water, or they may be placed in a steam sterilising apparatus under pressure. Rubber nipples for infants' bottles must be kept in borax water and rinsed several times daily. Rubber tubing should be discarded.

The heat of Pasteurisation is sufficient to destroy all bacteria likely to be present without so much alteration of the properties of the milk as occurs in sterilisation.

Different experimenters have shown that the tubercle bacillus in milk is destroyed by a ten-minutes' exposure at 1670 F., whereas the germs of cholera, pneumonia, and typhoid fever may be quickly destroyed in milk at 1400 F. (Van Geuns).

Freeman has shown by experiments that -

"1. Pasteurisation of milk at 750 C. (1670 F.) affords a safeguard against the deleterious effects of any bacteria which it may contain, without interfering with its nutritive qualities.

"Pasteurisation at about 750 C. (1670 F.) destroys efficiently the germs of cholera, typhoid fever, diphtheria, and tuberculosis as well as the Streptococcus pyogenes, the Staphylococcus pyogenes aureus, and the Bacillus coli communis".

The Bacillus acidi lactici is also prevented from acting after exposure to a temperature of 1600 F.

It is found that by immersing bottles' of milk in water which has just been removed, while boiling, from the fire, a fairly uniform temperature of 1670 F. is obtained. Naturally, the relation between the volume of water used and the quantity of milk must be properly balanced, and various forms of graduated receptacles are sold which make the process very easy and simple.

A graduated covered pail, into which the boiling water is poured, is fitted with a rack to submerge enough bottles of milk for the day's use, and this is all that is necessary. After half an hour's exposure to the heat the milk, as in the case of sterilised or pancreatinised milk, is set in a refrigerator until ready for use.

Under some conditions both sterilised and Pasteurised milk form smaller curds than raw milk, although this is not the case with the coagulae formed by gastric juice (Freeman).

The poor in New York city are now supplied with cheap Pasteurised milk through the philanthropy of Mr. Nathan Straus, who in

1893 opened the first milk depot for dispensing pure milk and Pasteurised milk, at a cost of but one and a half cent for an eight-ounce bottle. A sterilised nipple is also furnished with each bottle. The bottles have sloping necks, to facilitate cleansing, and spheroidal bottoms to prevent them from being left standing about uncorked. In an account of this system by Dr. Freeman he states that:

"In addition to Pasteurised ordinary milk and Pasteurised modified milk, a Pasteurised milk diluted with barley water and sweetened with cane sugar, and containing also table salt, has been introduced at the suggestion of Dr. Jacobi. The formula used is:

Table salt................................................. oz.

White cane sugar.......................................... 10 oz.

Milk...................................................... 1 gal.

Water................................................... 1 gal.

" This barley milk will be dispensed in six-ounce bottles".