The name ‘protein’ is derived from the Greek word ‘proteius’, meaning primary, and indicates the importance of this class of compound in all forms of living matter. All living cells contain propein, and muscle tissue is primarily protein. Proteins may defined as substances composed principally of amino-acids, chemically combined. Carbon, Hydrogen, Nitrogen, Oxygen, Sulphur and in a few instances, Phosphorus are the element present in proteins. The richest sources of a protein are lean meat, cheese and eggs. Cow’s milk contains approximately 3.55 percent protein. Other foods contain protein in varying amounts.