28 DAIRY LABORATORY GUIDE 



EXERCISE VIII 

 STARTER MAKING 



Sterilize a clean-flavored batch of sweet skimmed 

 or whole milk by running it through a pasteurizer 

 and heating to about 212 F., preferably two days in 

 succession. Allow the milk to run into a sterile 

 quart bottle. 1 Cover spout of pasteurizer and open- 

 ing in the bottle with clean white cloth or parch- 

 ment paper to prevent contamination from the 

 surrounding atmosphere, as in the case of pasteur- 

 ization. Cover bottle as soon as full and cool to 

 80 F. Add contents of bottle or capsule of com- 

 mercial culture and allow to remain at 80 F., until 

 rnilk becomes partially thickened, or has the consist- 

 ency of* thick cream. This usually requires from 

 eight to twelve hours. At this stage it is called 

 startoline. Pour from the top of the bottle into a 

 can containing from five to ten gallons of pasteur- 

 ized milk the entire contents of the bottle, with the 

 exception of about one tablespoonful remaining in 

 the old bottle. Put the spoonful of starter remain- 

 ing in the old bottle into a clean sterile bottle and 



1 Where glass jars are used a steaming cabinet is very con- 

 venient. This should be made to hold three times as many 

 jars as are required daily. Place one day's supply in, heat to 

 from 200 to 212 F. for half an hour. On the following day add 

 a like number and repeat the heating. On the third day add 

 another day's supply and again repeat the heating. The first 

 jars have now received three applications of heat and are prac- 

 tically sterile. By replacing each day as many jars as are taken 

 out a supply of sterile mother starter is constantly on hand. 



