CARE OF MILK AND CREAM 1Q7 



them to reform, but if they will observe the 

 filthiness of this practice they will recognize 

 it as a great source of contamination. 



EXERCISES 



1. How many bacteria are there in a cubic centi- 

 meter of ordinary milk twenty-four hours old ? 



2. Are these bacteria larger or smaller than the 

 fat globules? 



3. How do bacteria get into the milk? 



4. Why not keep the bacteria out by straining the 

 milk through very fine absorbent cotton? 



5. Will milk sour if kept at a temperature of 45° F. ? 



6. What causes some milk to be "ropey"? 



7. Is colostrum milk poisonous ? 



8. Why do we have more bitter milk in the winter 

 time than in the summer time? 



LABORATORY PROBLEMS 



XVIII. To Determine the Influence of Adding Water to 

 Milk on the Lactometer Reading and Fat Content 



1. Take a quart of milk and determine the lacto- 

 meter reading and fat content of the same. 



2. Add varying quantities of water, for example, 

 10 c.c, 20 c.c, 40 c.c, per 100 c.c. of milk and mix 

 well. Determine the lactometer reading and fat con- 

 tent in each case. 



3. Compare results obtained with those obtained 

 under 1. 



LABORATORY PROBLEMS 



XIX. To Determine the Purity of Milk by Means of the 



Fermentation Test 



1. Carefully wash with cleaning powder and hot 



