Why does ground beef turn brown?

[luke from georgia]

i bought a package of ground chuck at publix on sunday. at the time, it was red. it's raw meat, so i expect it to be red. today, it's brown. it's still raw, but not red like it was. i've seen this happen to old frozen ground beef, too.

does that mean the meat is spoiled?

[imported_delmonico]

No it means the hemoglobin in the meat has oxidized a bit. Should still be fine, smell it first to check for spoilage.

[Allie]

It's fine unless it smells.

[luke from georgia]

it smells good. into the pan it will go!
thanks!

[Dad of Toby]

Because the heat cooks it.....and it turns brown.

[Paddysmom]

No it means the hemoglobin in the meat has oxidized a bit. Should still be fine, smell it first to check for spoilage.

What a great piece of info, Glen! Thanks very much for that.

[Sams Mom]

No it means the hemoglobin in the meat has oxidized a bit. Should still be fine, smell it first to check for spoilage.

You beat me to it.

Of course I didn't know what chemical oxidized.It's the same with apples, avocados and bananas. They go brown (after you cut them) because of oxidation. You can stop that oxidation with citric acid (lemon juice/orange juice/pineapple juice). Not sure what you'd use for ground beef.

[imported_Nick]

No it means the hemoglobin in the meat has oxidized a bit. Should still be fine, smell it first to check for spoilage.

I don't think it's because the hemoglobin or myoglobin has oxidized as much as it has denatured or broken down. When both of those proteins accept oxygen, they turn red. Another possibility is that the blood has drained out, along with the color. It's sort of like how we turn blue without enough oxygen, the meat, I'm assuming, will lose its red color if the hemoglobin can no longer accept oxygen.

I don't know which one is more responsible, simple drainage or the protein breaking down...basically I'm just guessing.

[patm]

Some places treat meat with carbon dioxide to make it keep it's red color. It doesn't stay fresher longer - just looks that way

Giant, Safeway Inc and Tyson no longer use CO to treat meat and fish. Target has continued the practice, but today they "asked USDA for approval to add a warning to the label of meat that has been treated with carbon monoxide sold in its stores." We're not sure about the contents of the label, but its likely to be similar to the "Use by this date" warning suggested by Hormel and Cargill.

Bottom line: unless you know for sure your store doesn't use carbon monoxide on its meat, don't equate color with freshness, because the practice isn't going away any time soon.