118 Dairy Bacteriology. 



Many proprietary compounds for milk preservation 

 have been placed on the market in the past, but the use 

 of all of these is illegal in most states. The federal law 

 also prohibits their use in all dairy products that pass 

 into interstate commerce. 



Within recent years a method for the preservation of 

 milk was introduced by a Danish engineer, Budde, which 

 consists of adding to milk a very small amount of peroxid 

 of hydrogen which is a very efficient antiseptic. The 

 peroxid is decomposed by some substance in the milk ; 

 the products of decomposition being water and free 

 oxygen. The peroxid together with the application of 

 heat at a comparatively low temperature (122 P.) is 

 sufficient to destroy the larger part of the bacteria in 

 the milk. Practical difficulties are encountered in the 

 commercial application, so that it is probable the process 

 will never be a commercial success. 



For the preservation of composite samples of milk for 

 analytical purposes, such as the Babcock test, strong dis- 

 infectants, as corrosive sublimate, are employed. This 

 material is very poisonous, and leaves the milk un- 

 changed in appearance. Some coloring matter is there- 

 fore usually mixed with the sublimate in making the 

 preservative tablets, so as to render their use more con- 

 spicuous. Corrosive sublimate not only stops all bac- 

 terial growth, but quickly destroys the life of the cells. 

 Bichromate of potash is generally employed in the pres- 

 ervation of composite samples for the Hart casein test. 



Destruction of bacteria in milk. Actual destruction 

 of the life of bacterial cells by heat is one of the most 

 important ways for preserving milk. Heat easily de- 

 stroys the vegetating, growing bacteria, while the spores, 

 of which there are always a number in milk, are very 



