MILK AND ITS PRODUCTS 197 



from overripening, so that its original good flavor may 

 be seriously impaired at the end of one month's use. It 

 is only where the utmost precautions are taken in pas- 

 teurizing the milk and ripening the starter, that it is 

 possible to propagate a starter for many weeks and still 

 maintain a good flavor. 



POINTERS ON STARTERS. 



1. Starters give best results when added to cream 

 or milk immediately after they have thickened. 



2. An overripe starter produces somewhat the same 

 effect in butter as overripened cream. Curdy flavors are 

 usually the result of such starters. 



3. To prevent overripening, starter cans or starter 

 vats must be used in which the temperature can be kept 

 under perfect control. 



4. Skim-milk furnishes the best medium for starters, 

 since this has undergone the cleansing action of the 

 separator and is free from fat, which hampers the growth 

 of lactic acid bacteria. 



5. Agitate and uncover the milk while heating to in- 

 sure a uniform temperature and to permit undesirable 

 odors to escape. 



6. Always dip the thermometer in hot water before 

 inserting it into pasteurized milk. The pasteurizing pro- 

 cess becomes a delusion when dirty thermometers are 

 used for observing temperatures. 



7. Always use a sterilized can for making a new 

 starter. 



8. Keep the starter can loosely covered after the milk 

 has been heated to prevent germs from the air getting 

 into it. 



