102 GRADING AND TESTING MILK AND CREAM 



every creamery has its own conditions and problems to meet, and 

 consequently should be in a position to determine, readily and 

 accurately, what its losses of fat in the buttermilk are. It will 

 then be in a position to study how to reduce them. 



The third point is that the average creamery, under its 

 methods of testing, is not aware of what its losses are. It is not 

 uncommon to note, in creamery records, tests of .1 per cent to 

 .2 per cent for the buttermilk, whereas it is known, from hun- 

 dreds of analyses made in the laboratory of the American Asso- 

 ciation of Creamery Butter Manufacturers, that the average 

 loss exceeds .5 per cent fat. The loss does not fall far short of a 

 pound of butter to every hundred pounds of buttermilk. 



Realizing the necessity for a simple test that would corre- 

 spond closely with chemical analysis for buttermilk (or skim- 

 milk) , and that could be operated by anyone capable of conduct- 

 ing a Babcock test, the senior author asked Professor Mitchell to 

 devise such a test, if possible. In his efforts he has fortunately 

 been very successful. 



The different methods of making a Babcock test of butter- 

 milk, including the new modification of the same, are briefly out- 

 lined below. 



The following method of testing buttermilk (or skim-milk) 

 has been in use for many years, and is still more generally used 

 than any other. A double-necked skim-milk bottle, graduated 

 to read as close as .01 per cent for 18 grams, is used. Most of 

 the bottles read up to .25 per cent some to .50 per cent. After 

 the buttermilk is well mixed, a 17.6 c.c. pipette is used to transfer 

 18 grams of it to the test bottle. To this is added 20 c.c. of 

 commercial sulphuric acid (sp. gr. 1.82-1.83). The acid and milk 

 are then thoroughly mixed by giving the bottle a gentle, rotary 

 motion. Care must be exercised, in mixing, to avoid choking 

 the small neck and causing some of the contents to be thrown 

 out through the large neck. The bottle is then placed in the 

 centrifuge and whirled at full speed for about five minutes. 

 Hot water (soft or distilled) is then added to the bottle to fill it 

 almost to the neck and the machine is again run for one or two 

 minutes. Hot water is then added to float the fat into the small 



