Babcock test

The Babcock test is the first inexpensive and practical test factories could use to determine the fat content of milk.

Motivation

Until the 1890's, dishonest farmers could water down their milk or remove some cream before selling it to the factories because milk was paid for by volume. Honest farmers, as well as those that produced naturally rich milk, were not being compensated fairly.

Babcock Test process

Stephen Moulton Babcock researched the problem at the University of Wisconsin-Madison and developed the following process:

1. Measure milk into graduated test tube. You usually take 18 grams of milk or 17.6 milliliters.
2. Add 17.6 milliliters of 90-92% sulphuric acid.
3. Centrifuge at 50ºC.
4. Measure fat which will be floating on top of liquid in the test tube.

Principle of Babcock test

Key to this process is that everything in milk except the fat dissolves in sulphuric acid. The fat floats to the top. The centrifuge ensures complete separation with no bubbles in the fat, and the fat content can be measured using the graduations on the test tube and knowing the initial amount of milk used.

Utility of Babcock test

After the development of the test, it was much easier for a dairy operation to not only compensate farmers fairly, but to produce a consistent product that consumers could depend on. The Babcock test was also utilized by farmers to selectively breed for cows who produced milk with higher butterfat content—the tests were usually done monthly by an employee of the local Dairy Herd Improvement Association (DHIA).

About Babcock

Professor Babcock did not patent his invention considering himself an agent of Wisconsin working for the welfare of Wisconsin.

See also

• Stephen Moulton Babcock
• Hydrometer Device for measuring milk's relative density