Metmyoglobin

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Metmyoglobin (MbFe (III)) is the oxidized form of the oxygen-carrying protein myoglobin (MbFe (II)). It is caused by autoxidation in the body of vertebrates . Metmyoglobin is the cause of the characteristic brownish-gray discoloration of dead meat that occurs during storage. During the oxidation, the iron (II) changes to an iron (III) ion .

physiology

There is a balance in the body between the Fe (II) and Fe (III) forms of myoglobin, so that a constant two to three percent of the total myoglobin consists of MbFe (III) (the same applies to hemoglobin / methemoglobin ). Metmyoglobin can also be activated by reacting with hydrogen peroxide (H 2 O 2 ) to perferryl myoglobin, an excited state that quickly decomposes to ferryl myoglobin MbFe (IV) = O, in which iron has the coordination number  4.

Food chemistry

In dead muscle tissue , the concentration of metmyoglobin increases when there is a lack of oxygen in the packaging (e.g. when pieces of meat lie on top of each other). The normal process of breaking down metmyoglobin through the pores is blocked in this way and the iron contained in meat becomes discolored (oxidized).

With color stabilization in meat technology, the addition of nitrite metmyoglobin and nitrosyl .

Together, both form stable complexes of bright red color (nitrosylmyoglobin and nitrosylmetmyoglobin). The process is known as reddening .

Individual evidence

  1. a b C. P. Baron, HJ Andersen: Myoglobin-induced lipid oxidation. A review Archived from the original on March 4, 2016. Info: The archive link was automatically inserted and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF) In: J. Agric. Food Chem . 50, No. 14, July 2002, pp. 3887-3897. PMID 12083855 . Retrieved March 12, 2013.  @1@ 2Template: Webachiv / IABot / www.aseanbiotechnology.info
  2. DA Ledward: Metmyoglobin Formation in Beef Stored in Carbon Dioxide Enriched and Oxygen Depleted Atmospheres . In: Journal of Food Science . 35, No. 1, August 2006, pp. 33-37. doi : 10.1111 / j.1365-2621.1970.tb12362.x .
  3. ^ Hans-Dieter Belitz , Werner Grosch , Peter Schieberle : Textbook of food chemistry . 6th completely revised edition. Springer, Berlin / Heidelberg 2008, ISBN 978-3-540-73201-3 , p. 593 , doi : 10.1007 / 978-3-540-73202-0 .