The Babcock test is an inexpensive and practical procedure to determine the

fat content of milk The fat content of milk is the proportion of milk, by weight, made up by butterfat. The fat content, particularly of cow's milk, is modified to make a variety of products. The fat content of milk is usually stated on the container, and the color ...

. It is named after its developer,

Stephen M. Babcock Stephen Moulton Babcock (22 October 1843 – 2 July 1931) was an American agricultural chemist. He is best known for developing the Babcock test, used to determine butterfat content in milk and cheese processing, and for the single-grain experime ...

(1843–1931), professor at the

University of Wisconsin A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, t ...

.Stephen M, Babcock (1890): "A New Method for the Estimation of Fat in Milk, Especially Adapted to Creameries and Cheese Factories". In ''Annual Report'', Agricultural Experiment Station, University of Wisconsin.E. B. Hart (1949): "Stephen Moulton Babcock". ''Journal of Nutrition'', volume 37, issue 1, pages 1–7. Babcock milk testing bottle
. Item 2014.0223.06, Online catalog, Smithsonian Institution. Accessed on 2019-03-04.

History

The bottle and the test were developed by Stephen Babcock in 1890 as a simple but accurate way to detect adulterations practiced by some

dairy farm Dairy farming is a class of agriculture for long-term production of milk, which is processed (either on the farm or at a dairy plant, either of which may be called a dairy) for eventual sale of a dairy product. Dairy farming has a history that ...

ers, including diluting the milk with water or skimming some

cream Cream is a dairy product composed of the higher-fat layer skimmed from the top of milk before homogenization. In un-homogenized milk, the fat, which is less dense, eventually rises to the top. In the industrial production of cream, this process ...

. The test was quickly adopted by dairymen, and also by farmers to help the

breeding Breeding is sexual reproduction that produces offspring, usually animals or plants. It can only occur between a male and a female animal or plant. Breeding may refer to: * Animal husbandry, through selected specimens such as dogs, horses, and rab ...

of milk

cow Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult ma ...

s. The tests were usually done monthly by an employee of the local Dairy Herd Improvement Association. Babcock's refusal to patent his process or the device greatly helped its widespread diffusion.Babcock's Revolutionary Dairy Invention
Wisconsin Historical Society. In 1911, the

American Dairy Science Association The American Dairy Science Association (ADSA) is a non-profit professional organization for the advancement of dairy science. ADSA is headquartered in Champaign, Illinois. Consisting of 4500 members, ADSA is involved in research, education, and in ...

's Committee on Official Methods of Testing Milk and Cream for Butterfat, chaired by O. F. Hunziker, met in Washington DC with the Dairy Division of the

USDA The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...

, the

U.S. Bureau of Standards The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...

and manufacturers of glassware.Ernest O. Herreid (1942): "The Babcock Test; A Review of the Literature". ''Journal of Dairy Science'', volume 25, issue 4, pages 342–343. As a result of those talks, the procedure and the special glassware were standardized by the US government in 1917.Roscoe H. Shaw (1917): ''Chemical Testing of Milk and Cream''. U.S. Government Printing Office. Additional specifications were published by the Association of Official Agricultural Chemists (now AOAC International) in 1927.(1927):
AOAC 920.111-1920(1997), Fat in cream
. Digital document available from AOAC International. Catalog accessed on 2019-03-04.

Process

The test is based on the observation that a suitable amount of

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...

added to the milk will dissolve proteins and other components, except the

fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers spec ...

. Heating and centrifuging cause the fat to separate and float to the top, in a layer free of bubbles. The amount of fat in the milk can then be estimated from the volume of that layer. The procedure was commonly carried out in a special flask with a long neck, called a

Babcock bottle A Babcock bottle is a clear glass flask with a long graduated neck, used in the Babcock test to evaluate the cream contents of milk. It is also called a Babcock milk test bottle, milk test bottle, cream test bottle, and other similar names.

. Specifically, the test consisted of the following steps:Otto Frederick Hunziker (1917): "Specifications and Directions for Testing Milk and Cream for Butterfat". ''Journal of Dairy Science'', volume 1, issue 1, pages 38–44. # Place 17.6 mL (18

gram The gram (originally gramme; SI unit symbol g) is a Physical unit, unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram. Originally defined as of 1795 as "the absolute weight of a volume of pure wate ...

s) of milk into a Babcock bottle. # Add 17.6 mL of 90-92%

at 15-20°C. # Spin the flask in a hand-cranked

centrifuge A centrifuge is a device that uses centrifugal force to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities (e.g. cream from milk) or ...

for 5 minutes. # Add water at 60°C until the fat layer is all in the neck. # Warm the bottle to 55-60°C and spin it for another minute. # Immerse the bottle upright in 55-60°C water until the fat layer is settled. # Read out the fat contents from the graduated scale. The scale on the neck was calibrated so as to give a direct readout of the percentage of fat in the original sample (assumed to be 17.6 mL), in 0.1 percent increments, without the need for computation.

Test for ice cream

The original Babcock test was not suitable for estimating the fat contents of

ice cream Ice cream is a sweetened frozen food typically eaten as a snack or dessert. It may be made from milk or cream and is flavoured with a sweetener, either sugar or an alternative, and a spice, such as cocoa or vanilla, or with fruit such as str ...

, since the sugar and other ingredients would be charred by the sulfuric acid and contaminate the fat layer. After thousands of experiments, a modified test, suitable for the purpose, was developed in 1930 by L. K. Crowe at the

University of Nebraska A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, the ...

. It used a solution of

ammonium hydroxide Ammonia solution, also known as ammonia water, ammonium hydroxide, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH3(aq). Although ...

in N-butyl alcohol, and a mixture of sulfuric acid and

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...

.L. K. Crowe (1930):
Testing Ice Cream for Butterfat
. Bulletin 246, University of Nebraska at Lincoln, Department of Dairy Husbandry.

References

{{Reflist Milk University of Wisconsin–Madison

History

Process

Test for ice cream

See also

References