PASTEURIZATION OF MILK. 189 



less danger of spreading disease. In Denmark all 

 skim-milk and buttermilk must be heated to 180 

 degrees before it is returned to the farm. This plan 

 has materially lessened the spread of tuberculosis in 

 that country. Hydrogen peroxide is used to test 

 whether or not dairy products have been pasteurized, 

 and the law is rigidly enforced. 



The disadvantages of pasteurization are : 



1. The extra cost for labor and machinery to heat 

 and afterwards cool the milk or cream. A milk pas- 

 teurizer that will heat milk for two power separators 

 will cost from $150 to $200. 



2. There is difficulty in pasteurizing milk or cream 

 which is " over-ripe," and this may cause trouble in 

 hot weather, when milk or cream is not properly cared 

 for and cooled at the farm and is delivered in poor 

 condition. 



3. Some trouble is experienced from the froth which 

 rises on the milk as a result of heating. No practi- 

 cable remedy for this has yet been discovered. 



4. There is a tendency to lack of flavor, and some- 

 times there is a slightly " cooked " flavor as a result 

 of pasteurization. The cooked flavor usually disap- 

 pears in less than two weeks. Lack of flavor is 

 objectionable for local markets. 



Two points are essential if pasteurization is prac- 

 tised, viz., proper means of heating and cooling the 

 cream, and the use of a proper culture to give the 

 desired flavor to the cream and butter. Commercial 

 cultures should be propagated three or four times in 

 pasteurized skim-milk before they are used in cream 



