TREATMENT OF MILK FOR MARKET 151 



The process of boiling milk in the home for keeping it or 

 using it as an ordinary article of diet is fairly common. It is 

 more common in Europe than in America, and in the larger 

 cities in Europe most of the milk which is directly con- 

 sumed is first boiled. With those in our largest cities who 

 do not have ice chests the custom of boiling the milk is 

 also common, this being done for the purpose of keeping it 

 longer. Such sterilization or boiling certainly has some ad- 

 vantages. Sterilized milk will never distribute any of the 

 specific diseases above referred to, nor will it be the cause of 

 diarrheal troubles due to the excessive growth of bacteria in 

 milk. The inconvenience of boiling the milk, the development 

 of the "boiled taste" that it produces, together with the fact 

 that such milk is somewhat less digestible than the raw milk 

 have prevented a wider adoption of this method. It is prac- 

 tically certain that the solution of the milk problem of our 

 cities is not along the line of sterilizing or boiling. 



PASTEURIZATION OF MILK 



This procedure has recently become very widely known. The 

 name was derived from Pasteur, who devised the method for 

 treating wines and thus protecting them from various unde- 

 sirable fermentations. The essence of the process is the heating 

 of a liquid to a moderate temperature, sufficient to destroy many 

 but not all of the bacteria, and insufficient to produce any very 

 great chemical changes. The heating should be followed by 

 rapid cooling. Pasteurization destroys a large part of the 

 bacteria in milk, and this reduction in number greatly increases 

 its keeping property. 1 



The temperature at which pasteurization is performed varies 

 considerably in different methods. In some cases a temperature 

 as low as 140, maintained for an hour or more, is adopted; in 

 other cases the temperature of 160 is used for a short time, pos- 



1 Bitter. Zeit. f. Hyg., viii., p. 240, 1890. 



