Sudan changes to deep orange or red in the presence of lipids. Sudan in not soluble in water lipids will absorb sudan's particle that will cause the change in color. Lipids will form distinct fat layer in the solution. This can be done during experiment where a macromolecule is unknown. Application of this experiment applies in health such as during confirmation of excessive fat in stool. The affinity of this dye to the lipids is high and alcoholic solutions of sudan dye can also be used.
