In the test for protein, biuret reagent changes colour from blue to ___ in the presence of protein.
Sudha took a small amount of an unknown food item in a test tube. Then, she added a few drops of iodine to it. The colour of the unknown food item changes to blue-black.
The change in colour of the food item to blue-black indicates the presence of
Biuret solution turns ______ detecting the presence of proteins in food.