MILK SUPPLY AND CREAMERY PRODUCTS 71 



pensive to haul the milk a long distance to the creamery 

 and hand separators were introduced, each farmer skim- 

 ming his own milk fresh from the cows and delivering 

 the cream, only, to the creamery. This system has 

 the advantage of leavmg the skim milk on the farm 

 in the very best condition for the calves and hogs and 

 of saving time and expenses in transportation. It has 

 the disadvantage that many farmers can hardly be 

 expected to handle all of these separators as skilfully 

 and cleanly as the creamery expert can run his one or 

 few machines, and consequently that the skimming is 

 more or less imperfect — more butter-fat being left in 

 the skim milk and more impurities in the cream than 

 in the whole-milk creamery. But in practice the ad- 

 vantages of the hand separator and cream-gathering 

 system seem to be greater than the disadvantages and 

 it is rapidly taking the place of the whole-milk cream- 

 eries. 



Ripening the Cream. — Butter may be made by 

 churning whole milk, but usually it is made from cream 

 that has been ^'ripened" or soured by standing for 

 about 10 hours at a temperature of from 65° to 75° F. 

 Modern buttermakers often pasteurize the cream and 

 then add a ^'starter" to sour it. By preparing the 

 starter with a pure culture of lactic acid bacteria 

 one can get the desired acidity and aroma, and ex- 

 clude undesirable flavors (as to Pure Cultures and 

 Starters, see under '^Bacteria" and ^'Commercial But- 

 termilk"). 



The process of ripening requires considerable skill 

 and attention and is one of the most delicate functions 

 the buttermaker is called upon to perform. In the 

 first place the cream must be faultless, sweet and pure 



