ON BUTTERMAKING 23 



How is a commercial starter prepared for use? 



A small bottle containing a culture of lactic acid 

 producing bacteria is procured from some dairy 

 bacteriology laboratory, or from some reliable dairy 

 supply house. Directions are usually sent out with 

 these, but the following method is the one usually 

 followed : 



Place i quart of clean, sweet milk in a sterile glass 

 jar. Heat the milk gradually in water until a tem- 

 perature of 200 F. is reached. Hold at this tem- 

 perature for at least one hour. Then allow the 

 milk to cool to 90 F., being careful not to place the 

 glass suddenly in cold water. 



As soon as 90 F. is reached the content of the 

 small bottle is carefully added to the milk and 

 mixed through it. The mixture is now allowed to 

 cool gradually to 70 F. and then retained at this 

 temperature for 24 hours, when it should be sour. 

 This is called a " mother-starter," or " starter-line," 

 and is not to be used in ripening the cream, but in 

 preparing starter for the following day. 



To do this, take 100 pounds of clean, sweet skim 

 milk in a previously sterilized can and heat to at 

 least 200 F. for at least one hour. Then cool 

 rapidly to 70 F. and add the contents of the quart 

 jar prepared the day previous, mixing it thoroughly 

 through the milk with a sterilized dipper. Hold at 

 70 F. for 18 to 24 hours, when it should be sour, 

 slightly coagulated and clean in flavor. A small 

 amount of this is saved out to inoculate the starter 

 for the following day, and the process can be re- 

 peated and carried on in the same manner from day 

 to day. 



