Grade 



Date 



EXERCISE 23. (43) 



Object. — To prepare a commercial starter. 



Apparatus. — A pint bottle, sterilized; a sample of commercial starter; a 



sterilized graduated cylinder; a sample of pasteurized skimmilk; a 



thermometer. 

 Step 1. Measure out 25 cc. of the commercial starter into a sterilized pint 



bottle. Add to it 225 cc. of pasteurized skimmilk at a temperature of 



80° F. 

 Step 2. Place cover on bottle and set away in starter box at a temperature 



of 70° F. for 24 hours. Hold at this temperature until all changes have 



been noted. 

 Step 3. Record all the changes which a starter undergoes from the time it is 



made up until observations are complete. 



1. Write a full description of a starter and all the changes which take 

 place in its manufacture. 



2. Explain as fully as possible the reasons for each change. 



3. Give briefly the advantages of using a starter. 



