LACTIC STARTERS 45 



organisms, should be used in the preparation of starter. 

 The milk is ordinarily chosen from a producer whose 

 milk is usually in good condition. The quality of the 

 milk can be determined by the use of the fermentation 

 test. (See Chapter II.) It is better to choose only 

 the morning's milk for the making of starter, because 

 the bacteria have not had so much opportunity to 

 develop. In no case should the mixed milk be used in 

 the preparation of starter, as this eliminates all oppor- 

 tunity for selection. The flavor of the starter will be the 

 same as that of the milk from which it is made. 



62. Pasteurization is the process of heating to a high 

 temperature for a given length of time and quickly cool- 

 ing. It kills most of the micro-organisms in the 

 milk. In other words, it makes a clean seed-bed for 

 the pure culture. The temperatures of pasteurization 

 recommended for starter-making differ with the authority. 

 A temperature of 180 F. for thirty minutes or longer 

 seems to be very satisfactory, since under these condi- 

 tions nearly all the micro-organisms in the milk are killed. 



63. Containers. Various kinds of containers may 

 be used for starter-making. One-quart glass fruit jars or 

 milk bottles make very satisfactory containers, because 

 the condition of the starter may be seen at any time. 

 They are also easily cleaned. They have the disad- 

 vantage, however, of being easily broken, if the tem- 

 perature is suddenly changed, or if severely jarred. 

 Tin containers may also be used. Such containers are 

 not easily broken, but they are harder to clean and must 

 be opened to examine the contents; hence the liability 

 of contamination is very much greater. 



This small amount of milk may be pasteurized by plac- 

 ing the container in water heated to the desired tempera- 



