182 MODERN DAIRY PRACTICE. 



excellent chance to increase and start their characteristic 

 fermentations. In many places this is done from igno- 

 rance; in other places because the number or capacity of 

 the separators do not correspond to the quantity of milk 

 received. If the danger involved in such treatment of the 

 milk was properly understood, the expense of buying a 

 sufficient number of separators, or separators of sufficient 

 capacity, would not be considered. 



We saw on page 68 the advantage of pasteurizing the 

 unskimmed milk to be hauled away, so as to increase its 

 keeping quality. Pasteurization of milk is also often prac- 

 tised for another purpose viz., to obtain butter that will 

 keep better. It is both expensive and a waste of time to 

 separate the cream from such pasteurized milk by means of 

 any of the older methods, while it may easily be done by 

 application of the centrifugal method. Pasteurization of 

 the milk before separation not only gives a product that 

 will keep better, but also brings about another advantage, 

 as shown by Borje Norling: the production of a thinner 

 skimmed milk i.e., the cream is richer in fat. This 

 writer advises that new milk be first pasteurized, then 

 separated at about 159 F., the cream and the skimmed 

 milk to be cooled in separate coolers. He states that 

 numerous comparative trials have shown that if milk 

 is skimmed under similar conditions partly at common, 

 partly at pasteurization temperature, the skim-milk will 

 regularly show a lower fat content in the latter case.* 

 The method of pasteurizing the new milk before the 



* Limde found in his pasteurization experiments the following 

 average percentages of fat in the skim-milk, the speed and amount 

 of milk run through the separator being the same in both cases : 

 skim-milk from pasteurized milk, .14 per cent; from non-pasteurized 



