Why does (my) corned beef go moldy so quickly?

Whenever I’ve cooked one of those ready-to-cook corned beef roasts from the grocer, the leftover meat goes moldy in 3-4 days. Beef or pork roasts I’ve made don’t do this (at least not for a fairly long time), nor does corned beef lunch meat I get at the deli. So why does a corned beef I cook at home turn blue-green in a matter of days? Should I find a better butcher or brand, or does this just go with the territory?

Mine doesn’t last more than a day or two in the fridge. It either goes into sandwiches or is just snacked on.

At the risk of asking a stupid question, you are refridgerating the leftovers? Because I’ve never seen corned beef spoil any quicker than any other leftover cooked meat.

If you see a shimmery blue-green, that could be due to a thin film of something (probably grease?) on the surface of the meat. Thin films can produce blue-green shiny colors by interference effects, you’ve perhaps seen this on soap bubbles or oil slicks. I’ve seen this on corned beef, and it’s not mold, the corned beef is still perfectly good.

I agree with C K Dexter Haven. I don’t think mold will occur in such a short time, but I’ve seen corned beef with a greenish sheen on the outside, and it’s perfectly edible.

I find that with cooked meats, the taste, and sometimes the feel are more accurate in judging spoilage. The smell is usually quite noticeable, plus I use the following rule of thumb: if I’m not sure one way or another about the smell, assume it’s bad and chuck it. As for feel, some meats can get slimy/greasy feel as they go off.

Thanks for all the responses! A few replies:

Little Nemo, yes, of course I’m refrigerating it.

Huh, yes, it does often look like a thin blue-green film! And that’s not mold? Huh, again. It does look pretty disgusting, maybe I need to rinse the corned beef when it’s done cooking, would that help? Or perhaps cut off all the edges just a little. I’d really not like to eat blue-green meat, ew.

Purd Werfect: I know what you mean about smell/taste, and I’m (perhaps overly) careful about refrigerated meats being a little “off”, and I won’t eat them even if they seem fine, just a little off. However, I find that sliced deli meat, especially ham, can get a little ‘slimey’ but still be fine; I’m told that the sliminess is from the meat shrinking over time, forcing the moisture to the surface.

What C K Dexter Haven said.

Good to know. Thanks!

As I said, I knew it was probably a stupid question. But I was thinking maybe you had heard about how people used to preserve meat by brining it and thought that modern corned beef was preserved like this and didn’t need to be refrigerated.

Yeah, this is almost certainly solidified grease. Beef roasts often do this in the fridge, especially corned beef. Try taking a hunk and reheating it – I’d wager dollars to donuts that the coloration will disappear (or nearly so) as the grease remelts.

If it’s solidified grease, why does it not appear blue-green on day two in the fridge, but blue-green on day 4? If it’s not mold (or worse) what causes the change after a couple-three days?