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safe mince?
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I have mince in the fridge that is due to be used today but it has gone from red to a kind of brown colour. Do you know what causes this, and is it still okay to use it?
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At least here in the U.S. adding coloration or other such artificial "enhancers" is forbidden by law. The color of the 'mince" (hamburger here) is a chemical reaction to exposure to air... see here: "... Different colors of beef are simply different forms of the same pigment, myoglobin, a chameleon-like chemical that can be purple, red or brown, depending on its environment. The myoglobin in freshly cut, raw "red meat" is in the form of deoxymyoglobin, which is a dark, purplish-red color. On exposure to air it turns into bright red oxymyoglobin, the color we love to see in our meat as a putative indication of freshness. But inside a package of ground meat, oxygen is unavailable, and after a few days, most of the myoglobin turns into its metmyoglobin form, which is a grayish brown. It may still be perfectly good meat.
Retailers control the oxygen exposure by covering the package with a plastic film that, while blocking out microbes, allows just enough oxygen penetration to keep at least the meat's surface a nice, red oxymyoglobin color. That's the most commonly used packaging method. But perversely, myoglobin can also turn into brown metmyoglobin from too long an exposure to air. That's how meat left out too long gets "old."
Another widely used method is to seal the meat while in its red oxymyoglobin form in a gas-tight package containing not air, but a mixture of gases that have no effect on myoglobin: usually nitrogen and carbon dioxide. Variations of this so-called "modified atmosphere packaging" have been in use for the past 50 years or so.
" (Source: University of Wyoming Agricultural Department).
Retailers control the oxygen exposure by covering the package with a plastic film that, while blocking out microbes, allows just enough oxygen penetration to keep at least the meat's surface a nice, red oxymyoglobin color. That's the most commonly used packaging method. But perversely, myoglobin can also turn into brown metmyoglobin from too long an exposure to air. That's how meat left out too long gets "old."
Another widely used method is to seal the meat while in its red oxymyoglobin form in a gas-tight package containing not air, but a mixture of gases that have no effect on myoglobin: usually nitrogen and carbon dioxide. Variations of this so-called "modified atmosphere packaging" have been in use for the past 50 years or so.
" (Source: University of Wyoming Agricultural Department).
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