Proteins are polymers of amino acids. They are complex organic compounds containing nitrogen, hydrogen, carbon and oxygen. Proteins are abundant in our everyday food e.g. egg, soya bean, pulses, fish, milk etc. The presence of proteins can be confirmed qualitatively by usign several tests, Xanthoproteic test is one of them. Due to the presence of characteristic side chains in them, certain amino acids exhibit typical color reactions that form the basis for their identification.