Appearance of colour on adding and caustic soda to the food item indicates the presence of proteins.
When copper sulphate and caustic soda are added to a food sample, a violet color indicates the presence of proteins in the food.
In an experiment, Radha took small amounts of an unknown food item in a test tube. Then, she added two drops of copper sulphate solution in the test tube along with a few drops of caustic soda solution. After a few minutes, the colour of the food item changed to violet.
In the given experiment, the change in colour of the food item to violet indicates the presence of