TREATMENT OF CREAM PREVIOUS TO THE CHURNING. 223 



renewed every day by adding sweet skim-milk. When a 

 disease of the butter is being fought, pure cultures must 

 for some time be applied every day for preparing the 

 starter; otherwise a fortnightly application of pure cultures 

 will suffice." 



In my latest experiments with pure cultures in practical 

 dairying I have used the following method of procedure : 

 Morning milk from a well-kept farm was separated as soon 

 as it came to the creamery. Part of the skim-milk obtained 

 was carefully pasteurized;* then cooled to 77-82 F. (25- 

 28 C.), and the pure culture added. The temperature was 

 not lowered below 68 F., and the milk, which was covered 

 by a clean cloth during the whole time, was therefore 

 curdled as early as the afternoon of the same day. The 

 cream separated in the morning was pasteurized (at 158 F.) 

 and cooled to about 39 F. It was kept at this low tem- 

 perature for at least six hours; but perferably until the 

 evening, being occasionally stirred. At about 6 P.M. it was 

 heated to 73 F., the starter was added, and the cream-can 

 then kept wrapped in a hay mattress at ordinary room 

 temperature (64 F.). The cream was stirred at least twice 

 during the evening, with an hour's interval. It was usually 

 properly acid and uniform the next forenoon, and after 

 some cooling was poured into the churn.f 



*This milk may safely be heated to 185-194 F. (85-90C.). 

 Even if the starter has a cooked taste, the cream ripened by it will 

 not according to my experience have this taste unless extraordinarily 

 large proportions of starter are used. 



fThe starter used by C. O. Jensen in his experiments was pre- 

 pared in the following manner, according to his own description : 

 "200-600 cc. (about 7-20 oz.) of milk was drawn from the cow, 

 the udder and teats having been washed with a corrosive-sublimate 

 solution (1.1000) ; the teats were then wiped with a sleamed towel, 



