Nov. 26, 1917 
Enzyms of Milk and Butter 
445 
The extracts from the unsalted butters were not dialyzed. This 
accounts for their higher initial acidity. 
Lipase activity during four days at 40° C. was too small to be accurately 
measured, except in the extract from the stored centralized butter. 
in. oxidase content oe miek and butter 
Since the investigations of oxidase activity in milk have been limited 
to a few easily oxidized substances and since oxidases show a specificity 
toward chemicals in their action, it was thought desirable to investigate 
by Bunzel’s method the action of milk on several of the common chro¬ 
mogens (7). Four c. c. of milk were used in each test. Negative results 
were obtained with paraphenylene diamine, phenolphthalein, hydro- 
quinon, pyrocatechin, phloroglucin, a-naphthol, and para-, meta-, and 
ortho-cresols. Positive results were obtained with metol and pyrogallol; 
but since the action of the latter was about 20 per cent the greater, 
pyrogallol alone was used for the final determinations. The results given 
in Table VIII were obtained in duplicate, the duplicates agreeing very 
closely. 
Table VIII. — Estimation of oxidase in milk as shown by the oxygen absorption of 
pyrogallol 
[Readings are expressed as millimeters of mercury, each millimeter representing an absorption of 0.025 c. c. 
of oxygen.] 
Time. 
Skim milk 
z. 
Whole milk. 
Skim milk 2. 
Raw, 
Boiled. 
Raw. 
Boiled. 
Minutes . 
60. 
0. 16 
O. OO 
O. OO 
0. 00 
no 
. 40 
. OO 
. OO 
IOO. 
. OO 
• 17 
. OO 
120. 
0-95 
. 70 
. 16 
• 17 
. OO 
140. 
1. 07 
. 20 
•35 
. OO 
160. 
1. 28 
•97 
.27 
.40 
. OO 
180. 
i- 33 
13 
.40 
. 
300.. 
1. 70 
.91 
36°. 
1. 97 
I. 22 
420. 
2. 25 
I. 48 
460. 
2. 32 
I- 55 
There was no agreement in the results obtained from the skim m ilk 
from the same herd on different days; boiling failed to completely inhibit 
the activity of the whole milk, and the action was very slow in starting. 
It can not be caused by a normal milk oxidase. In every case a browning 
of the samples was quite marked before oxygen absorption started. 
Seven curd solutions from different butters gave no action with 
pyrogallol. 
15755°—17 - i 
