12 A Handbook for Dairymen 



these conditions nearly all the micro-organisms are 

 killed. 



The small amount of milk needed for starter 

 making may be pasteurized by placing the container 

 in water heated to the desired temperature. A very 

 satisfactory arrangement is to cut off a barrel and 

 place a steam pipe in it. Two or three extra 

 bottles should be prepared, as some of them may be 

 broken. Fill the bottles about two-thirds full so 

 that there will be room enough for the mother 

 starter and for later examination. To avoid pos- 

 sible contamination, it is desirable not to have the 

 milk or starter touch the cover. It is a good plan 

 when pasteurizing to have one bottle of water as a 

 check. Test the temperature for all the bottles by 

 inserting a thermometer in the bottle filled with 

 water. Never put a thermometer in the starter 

 bottles. Uniform temperature may be obtained by 

 shaking. 



Cleanliness. 



A successful starter can only be made if all uten- 

 sils coming in contact with the milk are sterile. Keep 

 the covers on the containers at all times. Don't put 

 thermometers into the bottles. When examining the 

 starter, pour it out — never dip into it. If the 

 cover is removed from the container, put it in a 

 sterile place. It is easy to spoil the culture if the 

 cover becomes contaminated. 



Glass fruit jars, or quart milk bottles, or tin 

 containers may be used for starter making. The 

 first two are more easily cleaned and their content is 

 always visible, but they break easily. The tin con- 

 tainer does not break, but it is hard to keep clean 

 and the chance for contamination is exceedingly 

 great. 



