CHAPTER IV* 



RELATION OF MICROORGANISMS TO SOME SPECIAL 

 DAIRY PRODUCTS 



GENERAL 



There is a number of special dairy products which do not normally 

 come into a discussion of market milk, butter or cheese, but which are 

 of considerable importance. A book of this sort would not be complete 

 without a discussion of some of these products from the bacteriological 

 standpoint. Some of these special products have been developed 

 as commercial enterprises and the processes of manufacture have been 

 zealously guarded as trade secrets. The result is that there is very little 

 available data on the manufacture of these products and very little 

 authoritative knowledge about their bacteriological condition. It is, 

 therefore, difficult to give a full discussion of the microbiology of these 

 products. A few of the more impqrtant ones will be discussed, however. 



CONDENSED MILK 



There are at least three quite distinct kinds of condensed milk 

 made under conditions which result in an entirely different bacteriolog- 

 ical condition in the finished product. These different products must, 

 therefore, be considered separately. Condensed milk means simply 

 milk from which a large part of the water has been removed, thus 

 decreasing its bulk, the purpose being to lessen the cost of transportation 

 and to increase the keeping quality of the product. Water is removed 

 from milk by some process of heating, either with or without vacuum, 

 the heating process being more or less equivalent to pasteurization. 



SWEETENED CONDENSED MILK. This product is made by reducing 

 cow's milk at the ratio of two and one-half to two and three-fourths 

 parts of fresh milk to one part condensed milk, by means of heat 

 and the addition of cane sugar. It is then put up in sealed cans. 



* Prepared by W. A. Stocking. 



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