Chemical analysis of ammonia in milk.
By Dr. Marina Bicchiega (cdr laboratories).


Raw milk's hygienic quality is determined by a set of factors such as the animal's state of health, and the milking, collection and transport procedures. The possibility of carrying out quick checks, in real time, of the microbiologic and hygienic quality of milk allows intervening readily on milking and collection procedures and preventing the introduction of poor quality milk into the transformation and distribution processes.
However, the traditional microbiological techniques are not presently capable of satisfying the requirements of rapidity and simplicity that are necessary for effective monitoring. The test for ammonia, on the other hand, can be a quick and reliable indicator of milk's total hygienic quality.
In fact, since ammonia is a metabolite of microbial activity, there is a correlation of 0.82 between the total bacterial charge in the milk and its ammonia content, as confirmed by recent studies [1]. Furthermore, the ammonia value, not being sensitive to thermal treatments such as pasteurization, can be a useful indicator of quality even for pasteurized milk [1,2,3,4].
An analyzer capable of carrying out the chemical analysis of ammonia in milk proves itself thus to be of considerable importance for milk production centers, for companies that deal with the transformation and packaging of milk and its by-products, for institutes assigned to the control and for dairy industry research laboratories.

[2] Determination of ammonium in milk and dairy products by ion chromatography Gaucheron F, Le Graet Y INRA, Laboratoire de Recherches de Technologie Laitiere, Rennes, France.

[3] Berthelot, M., Report Chem, Applique, 1 (1859) 28

[4] Ann Clin Biochem 1978 Sep;15(5):270-5 Optimal conditions for the estimation of ammonium by the Berthelot reaction Gordon SA, Fleck A, Bell J.