DAIRYING 47 



478. These tests show that the acidity of the different 

 samples reached a maximum beyond which it did not develop even 

 though they were held under favorable conditions for souring. 

 They also show that buttermakers should not expect cream con- 

 taining 25 and up to 50 per cent, fat to develop an acidity beyond 

 the figures given in the table. A cream containing 25 per cent, 

 fat may reach 0.6 per cent, acid, but a richer cream such as a 40 

 per cent, fat cream will not sour much beyond 0.5 per cent acid. 



2. CONDITION OF THE MILK 



The cream from a perfectly sweet, clean milk will ripen more 

 slowly and in a much more satisfactory way than cream skimmed 

 from milk in which the ripening has already started. Milk that 

 has not been .properly cooled after milking and has begun to sour 

 from age or impurities will not supply a cream free from taints. 

 The defects of the milk are carried into the cream, and they are 

 often the cause of an abnormal ripening of the cream. 



When the milk is pure and free from all foreign matter as 

 well as taints the cream skimmed from it will be in such a satis- 

 factory condition that the buttermaker may be able to control the 

 ripening process and make an excellent quality of butter. This 

 is not to be depended on, however, if a great variety of bacteria is 

 carried to the cream from the impure milk. 



A large churning of butter may be injured by one lot of im- 

 pure milk and the entire quantity of milk or cream to which it is 

 added suffer a loss in butter price on that account. This does not 

 seem fair when a reasonable amount of care will keep milk and 

 cream sweet and pure. 



3. THE WEATHER CONDITIONS 



During hot, sultry weather bacteria- thrive and multiply rapid- 

 ly, but in a cool, clear atmosphere the growth of these ferments is 

 somewhat retarded. The effect of changes in the weather is often 

 noticed in cream which is ripened in open vats. Damp, dark, and 



