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Southern Wisconsin Cheesemakers' and Dairymen's Association / Proceedings of the tenth annual meeting of the Southern Wisconsin Cheesemakers' and Dairymen's Association held at Monroe, Wisconsin, Thurs. and Fri., January 27 and 28, 1910

Hart, T. B.
Variations in the amount of casein in cows' milk and the operation of the casein test,   pp. 44-53 PDF (1.9 MB)

Page 49

Operating the Casein Test at Cheese Factories.
The Hart casein test is a simple and rapid method of
determining the amount of casein in milk. It is based on
the use of a centrifuge for separating the casein after its
precipitation with dilute acetic sold. The centri uge used
is much like a Babcock tester, except that the pockets are
deeper and it is geared to run at a higher speed. The test
bottle resembles somewhat an inverted Babcock cream test
bottle. The complete outfit can be purchased from the
dairy supply houses.
C h I or o f or m -A  high grade of chloroform should
be used. This can be obtained at local drug stores at
about fifty cents per pound, depending upon the quantity
purchased. It is better not to buy over two pounds at a
time. When not in use the chloroform bottle should be
kept in a cool dark place.
A c e t i c A c i d -A 10 per cent acetic acid solution is
usually furnished by the supply houses, at 25 cents per
quart. If the glacial acetic acid (99)- per cent pure) is pur-
chased, at 10 per cent solution is made by diluting 10cc. of
the strong acid to 100cc. with clean rain water or condensed
steam. Then 25cc. of the 10 per cent acid are diluted to
1000cc. with water.  This gives a 0.25 per cent solution,
the correct strength for the casein test.  The acid bottles
should be plainly labeled, in order that acid of wrong
strength will not be used.
The testing should be done in a room the temperature
of which is about 60 degrees or 7') degrees F. The curing
room is a good place for the tester; the making room is
apt to be too hot in the summer or too cool in the
The milk samples should be at a temperature of 65
degrees to 75 degrees F. It may be necessary to warm or
cool the samples before testing, depending on the season.

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