This is natural protein from animal or vegetable sources that has been broken down with synthetic chemicals. Animal protein has been found to be similar in molecular srtructure to hair. The hydrolyzed protein should, however, be avoided in favor of completely natural protein that does not contain synthetic chemicals.
Hydrolyzed protein is a solution derived from the hydrolysis of a protein into its component amino acids and peptides. While many means of achieving this exist, most common is prolonged heating with hydrochloric acid, sometimes with an enzyme such as pancreatic protease to simulate the naturally occurring hydrolytic process.