UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 944 
Contribution from the Bureau of Animal Industry 
JOHN R. MOHLER, Chief 
Washington, D. C. 
May 12, 1921 
\ THE ALCOHOL TEST AS A MEANS OF DETERMIN- 
ING QUALITY OF MILK FOR CONDENSERIES. 
By A. O. Dahlberg and H. S. Garner, Research Laboratories, Dairy Division. 
CONTENTS. 
Page. 
Review of previous work 1 
Test methods used , 2 
Experiments at Grove City creamery- 4 
Comparison of acidity and alcohol 
tests of milk for condensing 4 
Relative value of acidity and alco- 
hol tests 8 
Page. 
Experiments at condenseries 9 
Work at Factory A 9 
Work at Factory B 11 
Conclusions 13 
List of references 13 
REVIEW OF PREVIOUS WORK. 
The urgent necessity for some means of determining the quality 
of milk received at condenseries and other dairy manufacturing 
plants has resulted in the continued use of the acid test even after 
its defects have become generally recognized. This test is based on 
the assumption that a titratable acidity above the normal for fresh 
milk indicates an increase in acidity due to bacterial action. 
It is well known, however, that a certain part of the alkali added 
to milk to obtain an end point with any given indicator is combined 
with constituents of the milk other than the acids. While this has 
been recognized it has not been generally realized how great a varia- 
tion in the apparent acidity may be due to this cause. It has been 
recently pointed out by Rice ( 1 ) 1 that the casein and the phosphates 
both combine with alkali and are subject to a sufficient variation to 
cause in some instances an apparent high acidity in fresh milk. 
Our own experience, which is not unusual, has shown that not 
infrequently milk rejected because of high acidity was fresh milk 
in which bacterial action was highly improbable. In making evapo- 
rated milk the most essential characteristic is the ability of the milk 
1 See list of references at end of bulletin. 
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