370 Animal Husbandry 
bottles. Tie some paper over the top to prevent contamination. 
(Bottle caps are good.) 
2. Fill the kettle or similar utensil about one-half full of water. 
3. Place the three bottles, each containing one-third of a quart 
of milk, in the water. (Bottles must not touch the bottom if 
heated over a fire). Support the bottles to prevent them from 
tipping over. Wire or cord may be used. 
4. Place on a stove or over a gas jet, or insert a steam jet. 
(Heat slowly to prevent breaking the glass.) Hold above 180° F. 
for 30 minutes (the boiling temperature is not too high). 
5. Cool at 90° F. (To prevent breaking the glass, lower the 
temperature rather slowly.) Shake the bottle often or the milk 
in the center of the bottle will not be cooled sufficiently. To cool, 
let a stream of cold water flow into the kettle. 
6. Loosen the covers but do not remove them. Open carefully 
the package of starter. Now remove a bottle cover or cap suf- 
ficiently to introduce the starter. (Pour in one-third of the com- 
mercial culture in each bottle.) Shake to distribute the lactic 
acid bacteria throughout the pasteurized milk. In shaking, use 
rotary motion to prevent contamination by the milk coming in 
contact with the cover. 
7. Incubate at about 70° to 85°. The temperature must be 
fairly constant. When a soft, custard-like curd forms, the starter 
is ripe. This will require from 12 to 24 hours. 
8. When ripe, set in cool place (50° or below) until time for 
examination. 
36. Stupy or STARTER MADE IN Last EXERCISE 
Object. To become familiar with a good starter. 
Materials. Starter made at last exercise. 
Directions. Without shaking the starter, inspect the curd for 
gas pockets. It should be perfectly free from gas pockets which 
indicate the presence of undesirable bacteria. Now shake well 
