Does it have an effect nutritonally?
No. The meat doesn’t change. Only the living organisms IN the meat change. But frankly, if you’ve ever eaten repackaged, old meat and realized WHY it was so yuck, you wouldn’t go back to the same store. I’ve bought bright, pink looking hamburger meat that was sticky inside, and stank quickly, turning brownish from the inside out.
Naturally, meat turns brown from the outside in, and a little brown won’t kill you. But irradiation works better on the surface than the inside, so irradiate meat rots from the inside out. When it goes brown, it isn’t just a little exposure to air; it’s rotten nasty.
So that’s how you know if meat has been irradiated: if it doesn’t turn brown after you open the package for a day. (Irradiated meat will turn dark red when it dries on exposure to air, so note that that’s NOT what I mean by brown.)
Some of the chain stores in smaller markets are really bad about recycling near-spoiled meat. They’re used to wringing every cent out of their product before ditching it (the bog-box stores have too much turnover to get like that sometimes). And the old meat managers may not understand that the meat is closer to rotten than they think it is.
Believe me: nothing can take the romantic nostalgia for small businesses like working in a small, franchised supermarket.