28 DAIRY LABORATORY GUIDE 



EXERCISE 10 



EFFICIENCY OF METHODS OF COOLING MILK AND CREAM 



Object: To determine the variation in quality of cream, 

 when cooled and kept at room temperature, when set in water, 

 and when cooled in a refrigerator. 



Apparatus : A small quantity of milk and freshly sepa- 

 rated cream, acid testing outfit, thermometers, six pint bottles 

 or containers, and a piece of cheesecloth. 



Steps: 1. Secure samples of fresh milk and cream, and 

 test them for acidity, odor, and flavor. 



2. Number the bottles in sets 1, 2, and 3; then measure 

 out three bottles of milk and three of cream. Cover each 

 with a piece of cheesecloth. 



3. Place set No. 1 in the open at the ordinary room tem- 

 perature. Place set No. 2 in cold running water, if possible. 

 Place set No. 3 in a refrigerator. 



4. Examine the samples at frequent intervals, not to 

 exceed twelve hours, and record all data. 



Rules for Grading Cream. 



First Grade: All sweet cream of clean odor and flavor, 

 with not to exceed .2% of acidity. 



Second Grade: All sour cream reasonably clean in odor 

 and flavor, with not to exceed .8% of acidity. 



Application: 1. Determine from data whether the but- 

 ter made from such cream would grade Extra, First, or Second. 



2. How much butter can be made in one year from a cow 

 giving 5000 Ibs. of 3% milk, allowing 16% O. R.? 



3. What will the butter be worth at current quotations 

 for the various grades? 



