TREATMENT OF MILK FOR MARKET 165 



Concentrated Milk. A new method of treating milk has been 

 recently devised which offers some exceptional advantages. The 

 process is covered by patents, but it consists in the withdrawal 

 of a considerable portion of the water from the skim milk, and 

 the subsequent remixing of the product with the cream in proper 

 proportion. In its preparation the use of heat by special devices 

 is adopted, and the skim milk is treated for about two hours to 

 a temperature of 140. This reduces it to a thick mass which 

 resembles cream. The cream, which has meantime been pas- 

 teurized, is now mixed with it in proper proportions, and the 

 material is then known as concentrated milk. When the proper 

 amount of water is subsequently mixed with this concentrated 

 milk, 3 parts of water to I part of milk, it is restored to its 

 original condition so closely as to be almost indistinguishable 

 from fresh milk. It tastes the same, it curdles with rennet, 

 cream rises upon it in much the same way as on fresh milk, 

 and so far as experimental tests have determined, its digestibility 

 is not in any degree impaired. 



The advantages of concentrated milk are several. I. Its 

 treatment at a temperature of 140 for two hours absolutely 

 destroys all disease germs, including the tuberculosis bacillus, 

 so that there is no possibility of the product distributing in- 

 fectious diseases. 2. The treatment reduces the number of 

 bacteria so greatly that the chance of the milk being the cause 

 of diarrheal troubles is practically removed. 3. The condensa- 

 tion of the milk increases the proportion of milk sugar. This 

 produces a substance in which bacteria do not grow readily, 

 although they grow rapidly enough if it is diluted with its 

 normal amount of water. As a result concentrated milk may be 

 kept, if cooled, for a very much longer period than any type of 

 fresh milk. If kept at a temperature of below 50, it will not 

 only keep sweet for six to eight days, but at the end of this time 

 the number of bacteria will be surprisingly few, for example: 

 in a series of tests, after six days the milk contained less than 



