The Gerber method is a primary and historic chemical test to determine the fat content of substances, most commonly milk and cream. The Gerber method is the primary testing method in

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and much of the world. The fairly similar Babcock test is used primarily in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, although the Gerber method also enjoys significant use in the U.S. as well. The Gerber method was developed and patented by Dr.

Niklaus Gerber Niklaus Gerber (8 June 1850 – 9 February 1914) was a Swiss dairy chemist and industrialist. He was born in 1850 in Thun, Switzerland. He attended the University of Bern and University of Zurich, studied chemistry in Paris and Munich and spent ...

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

in 1891. Milk fat is separated from proteins by adding

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

. The separation is facilitated by using

amyl alcohol Amyl alcohols are alcohols with the formula C5H11OH. Eight are known. A mixture of amyl alcohols (also called amyl alcohol) can be obtained from fusel alcohol. Amyl alcohol is used as a solvent and in esterification, by which is produced amy ...

and centrifugation. The fat content is read directly via a special calibrated butyrometer. Gerber developed specialized butyrometers (tubes),

pipettes A pipette (sometimes spelled as pipet) is a type of laboratory tool commonly used in chemistry and biology to transport a measured volume of liquid, often as a media dispenser. Pipettes come in several designs for various purposes with differing ...

, and

centrifuges A centrifuge is a device that uses centrifugal force to subject a specimen to a specified constant force - for example, to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby s ...

. Water baths built specifically for the Gerber tubes are often used. The test is still in widespread use today and is the basis for numerous national and international standards such as ISO 2446, International Dairy Federation (FIL) Regulation 105, BS 696 (United Kingdom), and IS 1223 (India). Larger facilities may prefer to use faster analysis techniques such as

infrared spectroscopy Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functio ...

as these greatly reduce the potential for user error and reduce the time and COSHH requirements. The test continues to be improved and standardized.

Problems likely to be encountered during Gerber butterfat content determination

The two major defects associated with the Gerber method include: # Charring – is observed as tiny black specs at the fat/non-fat interface in the butyrometer. This problem is due to charring of the milk proteins by the concentrated Gerber acid. It could also arise as a result of pouring the milk sample directly onto the acid in the butyrometer. To avoid charring, first, ensure the acid concentration is right. Secondly, while adding the milk sample, let it flow on the side of the butyrometer to avoid violent reaction when it drops on the surface of the acid. # Light colored fat column (with or without brown specs at the interface) – may affect one's ability to read the fat content correctly. This problem is due to weak acid, which fails to dissolve all the milk non-fat content. To avoid this problem, use sufficient volumes of the Gerber acid at the correct concentration.

References

External links

*Explanation of th
apparatus and procedure
for the Gerber test *The {{usurped,
ultimate guide to the Gerber method
} of butterfat content determination. Chemical tests Food analysis Milk Science and technology in Switzerland