Voi. Lxxmi. 
Published Weekly by The Rural Publishing Co., 
333 W. 30th St., New York. Price One Dollar a Year. 
NEW YORK, AUGUST 9, 1919. 
Entered as Second-Class Matter, June 20, 1879. at the Post XT ._ 
Office at New York. N. Y.. under the Act of March 3. 1879. N O. 4o4o. 
A Talk About Acid Milk 
When It Comes; What It Means 
Te there any way to help the acid in milk? We sell 
milk to people who will not take it unless it is below 
18 per cent acid. I have all young cow-s. and do not see 
why there should be an excess of acid in the milk. I 
have cooled in every way; have fed different feeds and 
cows run in ordinary pasture. Why should there be so 
much acid, and is there any way to overcome it? 
New York. mrs. m. j. l. 
A CID CONTENT.—When milk is drawn from the 
cow it has a slight acid reaction. In other 
words, there is some acid in it. but not enough to 
make it taste or smell sour, of course. Among other 
MILK SUGAR.—Another constituent of milk is 
sugar. If milk contained no sugar, or if it was pos¬ 
sible to keep all bacteria out of it. milk never would 
taste sour. In other words, it would simply contain 
the original mineral acidity found in it when drawn 
from the cow. However, milk always contains sugar, 
and no matter how careful we may be. some bacteria 
capable of changing a portion of this sugar over into 
milk acid, or lactic acid, as it is called, get into the 
milk. The rapidity with which these bacteria de¬ 
sample of low butterfat milk testing, say 0.14 per 
cent acid when drawn from the cow, will taste sour 
when the bacteria have converted enough of the milk 
sugar into acid so the milk shows by test 0.2 to 0.22 
per cent acid. This means then that 0.06 to 0.002 
per cent lactic acid has developed, and this, added to 
the 0.14 per cent originally in the milk, makes it 
taste sour. Now it is most interesting to note that 
a sample of high butterfat milk testing 0.2 to 0.22 
per cent when fresh, as is likely to be the case, also 
Guernsey Cow Pearl Rose of Beaver Ridge 63932. Fig. 3’ t 6 
constituents, milk contains about 0.7 per cent ash or 
mineral matter. The acid in milk when drawn from 
the cow is due to certain acid phosphates that make 
up a portion of this mineral matter; also to the pres¬ 
ence of a certain amount of carbon dioxide gas that 
is in the milk. On the average, milk contains 0.17 
per cent acid when drawn from the cow. Milk from 
breeds testing low in butterfat will have 0.12 to 0.16 
per cent acid, while high-testing milk .will contain 
0.16 to 0.22 per cent, and occasionally higher from an - 
individual cow. This acid does not harm the milk, 
never increases in amount, and does not seem to he 
sour, like the lactic acid that is developed later. 
velop acidity in milk, and hence cause it to taste 
sour, depends on the original number with which the 
milk is contaminated (contaminated from unsterile 
utensils mostly), and on the temperature at which 
milk is held. You of course know if milk is held at 
much above 55° F. it sours rather quickly. This is 
simply due to the fact that the temperature is right 
for these little organisms to grow and act on the 
milk sugar. 
THE SOUR TASTE.—The point at which milk 
begins to taste sour depends on the person tasting it 
and on the per cent of mineral acidity originally in 
the milk. For example, it has been found that a 
has to develop about 0.06 per cent lactic acid before 
it tastes sour. This would mean that the test would 
show 0.26 to 0.2S per cent at poiut of tasting sour. 
This proves that the per cent of original acid in the 
milk has nothing to do with the sour taste. 
CONDENSERY STANDARDS.—A condensery has 
to have the best quality of milk for condensing be¬ 
cause the milk is condensed 2 and a fraction parts to 
1, and hence every defect in it is in a general way 
multiplied by 2. If milk contains an appreciable 
amount of lactic acid this is also multiplied by 2 
and makes the condensed product have so thick and 
flaky a texture that it is impossible to shake it out 
