206 CREAMERY BUTTER MAKING 



The circulation of the water in the cooler is indicated 

 by the arrows. A cooler consisting of 12 discs will cool 

 the cream from two separators to within 10 degrees of the 

 temperature of the water. 



It will be noticed from the cut that the cooler is pro- 

 vided with a cover, but it is best to leave this ofif as pas- 

 teurized cream needs very thorough aeration. 



A cooler like that shown in Fig. 22 will cool and aerate 

 cream satisfactorily when made large enough. It should 

 be at least 10 feet long and i foot wide. Fig. 64 illus- 

 trates another form of cream cooler which has proved 

 very efficient. 



Pasteurization will not prove successful unless the 

 cream is rapidly cooled to at least 65° F. immediately after 

 it leaves the pasteurizer. 



During the past four years a great many experiments 

 have been carried out at the Michigan Dairy School 

 along pasteurizing lines, with a view of determining the 

 advantages of making pasteurized butter. 



The experiments have had for their immediate objects: 

 I. To study the relative merits of pasteurizing whole milk 

 and cream ; 2. To study the extent to which pasteuriza- 

 tion improves the cjuality of the butter ; 3. To study the 

 keeping quality of pasteurized butter. 



The results of these tests are briefly summarized as fol- 

 lows : 



1. There was practically no diiiference in the quality 

 of the butter produced from pasteurized whole milk and 

 that made from pasteurized cream. 



2. Where the milk was of average purity the butter 

 from the pasteurized cream scored on an average 3 points 

 higher than that from the unpasteurized, using 15% 

 starter in each case. 



