| MadSci Network: Chemistry |
> Why do meats turn brown when they are cooked?
This is an excellent question, and one which touches on a current food safety question of great importance.
Just a few short years ago we recommended that people cook their hamburgers until the center turned brown, to insure that all pathogenic E. coli were killed. Some recent research by the USDA indicates that some hamburgers will turn brown prematurely, before they have reached the inactivation temperature for pathogenic E. coli.
for more details see:
http://www.fsis.usda.gov/OA/news/colorpr.htm
and for a more technical summary, including scientific references see:
http://www.fsis.usda.gov/oa/pubs/colortech.htm
Ok, now I'll get off my food safety soapbox and answer your question <grin>.
I found your answer in the book:
Title: Food chemistry / edited by Owen R. Fennema. Publication info: New York : M. Dekker, c1976. pg 609.Meats can turn brown for a variety of reasons, but the primary factor is that the major meat protein myoglobin denatures (i.e. unravels) during cooking. This denaturation causes a rapid release of the "heme" pigment from the "globin" part of the molecule. The free heme is very sensitive to oxidation. On heating, red meat turns brown as the red molecule heme is converted to the brown molecule "hemin". Bear in mind this a simplistic explanation, as other reactions (amino acids + sugar -> maillard browning products) can also play a role.
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