Bacteriology 11 



It is the problem of the cheese or butter maker 

 first to keep the organisms pure, and second to in- 

 crease them to such numbers and in such an active 

 condition that they are commercially useful. The 

 common practice is to allow them to develop in some 

 material, usually whole milk or skimmed milk, or 

 even dissolved milk powder. 



The manufacturer's directions apply to average 

 conditions and must be varied to suit the individual 

 case. The directions should state the amount of 

 milk necessary for the first inoculation, usually one 

 or two quarts. 



Suggestions for Selecting Starter Milk. 



As the flavor of the starter will be the same as 

 that of the milk from which it is made, great care 

 should be used in its selection. The following sug- 

 gestions are offered to aid in this selection : only 

 clean-flavored sweet milk, free from undesirable 

 micro-organisms, should be used. Choose the morn- 

 ing milk because the bacteria have not had much 

 chance to develop. In no case should mixed milk be 

 used, as this eliminates all opportunity for selection. 

 Choose the milk from a producer who maintains 

 high standards and whose milk is usually in good 

 condition. The quality of the milk can be deter- 

 mined by the fermentation test. 



Pasteurization. 



Pasteurization kills most of the micro-organisms 

 in the milk and makes a clean seed-bed for the pure 

 culture. The temperature of pasteurization recom- 

 mended for starter making differs with the author- 

 ity. A temperature of 180° F. for thirty minutes or 

 longer seems to be very satisfactory because under 



