Cereal Chem 38:501 - 506.  |  VIEW ARTICLE

The Biuret Test as Applied to the Estimation of Wheat Protein.

A. J. Pinckney. Copyright 1961 by the American Association of Cereal Chemists, Inc. 

The biuret test developed by the author in 1949 for estimating protein content in wheat and flour has been modified to make it simpler and more accurate. Formerly, aliquots of cleared alkaline protein extracts were combined with measured amounts of the alkaline copper reagent. In the modified method the stabilized alkaline copper reagent is applied directly to the weighed sample for simultaneous extraction and reaction. Color intensities of the centrifuged test solutions, as determined in a spectrophotometer, are closely correlated with the protein contents of the samples as determined by the Kjeldahl method. Comparative tests indicate that sodium potassium tartrate is superior to glycerol as a stabilizer for copper in the biuret reagent.