Add some of the egg white to the Biurets solution in the test tube and mix thoroughly while still hand warming. Add 1-2 ml of Biuret reagent to all the test tubes. Test For Starch Test For Proteins Biochemistry Notes Science Notes Biology Notes To identify the presence of a macromolecule the predicted color change in the substances which will differ in each test. . The protein and biuret color-change reaction is a reaction in which the charge of copper ions in the biuret reagent change from a 2 to a 1 in the presence of the peptide. The normal color of biuret reagent is blue. Add 1-2 ml of the test solution egg albumin and deionized water in the respective test tubes. Benedict Test for Reducing Sugars Test detecting. Demonstration of the biuret test for proteins. That is because proteins are made up of polypeptides which in turn are made of amino acids joined by peptide bonds. A color change of blue to pur...