Definition of "peptone" [pep•tone]

• Any of various water-soluble protein derivatives obtained by partial hydrolysis of a protein by an acid or enzyme during digestion and used in culture media in bacteriology. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Is it _pepsin_, the active principle of the gastric juice, which converts proteids into peptone, that is wanting, or is there a deficiency of _pancreatin_?"
• "With weaker doses of antigen and with antigens that are harmless or practically so, such as peptone, the anaphylactic leucocytosis does not last as long but is nevertheless pronounced."
• "This is because the pancreatic ferment (trypsin) has digested the casein into "peptone," which does not curdle."