What does it mean if the biuret reagent turns yellow?

If the biuret reagent turns yellow, it indicates that there may be the presence of certain proteins or peptides, but the reaction is not typical. Normally, biuret reagent is used to test for proteins, producing a purple color in the presence of peptide bonds. A yellow color could suggest interference from other substances or the presence of specific compounds that alter the expected reaction. It's important to conduct further tests to confirm the nature of the substances present.