STARTERS 



231 



air prevents the development of certain injurious organisms, 

 which may be present and which require air for growth. 



However, fine starters can be made from either whole milk or 

 skim-milk, and the point of first importance is that the milk 

 used be sweet and in a clean, sanitary condition. 



The milk which has been selected for the mother-starter, or 

 starter line, is then pasteur- 

 ized. The pasteurization is 

 best accomplished by the 

 intermittent method. If 

 considerable milk is to be 

 pasteurized it is best to 

 make use of a clean, steril- 

 ized starter can. If only a 

 small portion is to be pas- 

 teurized, just enough for the 

 mother-starter, the milk can 

 be put directly into the jars. 

 The jar half full is about the 

 proper amount of milk to 

 use. The directions sent 

 with some pure cultures 

 recommend as much as half 

 a gallon or a whole gallon 

 of milk. As a rule better 

 results are obtained if only 



FIG. 80. An Incubating Chamber for 

 Starters. The inner compartment will 

 hold a pail of water and the bottles for 

 the mother-starters. The temperature 

 can be kept at any desired point by the 

 use of warm or cold water. The four- 

 inch space between the walls is filled with 

 hay or mineral wool. (Dairy Bac- 

 teriology, Russell and Hastings.) 



about a pint of milk is 

 taken. If the milk for the 

 mother-starter is pasteur- 

 ized in the glass bottles 

 or jars, it is advisable to set the bottles containing the milk 

 into cold water, covering the jar so as to prevent outside con- 

 tamination, and then heat up the water gradually. Care 

 should be taken not to insert these bottles suddenly into scalding 

 hot water, or to let the steam strike them, for either is likely to 

 crack the bottles. Care should be taken also to exclude water 

 from milk used for starters. It is advisable to heat this milk, for 



