I learned the thing about aging beef from my online friend who owned a satellite TV hacking forum in the late '90s. He was a major barbecuist! (I'm a published author. I'm allowed to coin words because of my literary license.
) He and I discussed cooking often, online, email, even on the phone.
He explained to me that last day steak was on sale as a manager's special only because the FDA has set such ridiculously stringent standards for beef shelf life that the markets are forced to sell it on the last day or throw it away. He said he would buy "last day" steaks and then let them sit in his refrigerator another week or even two!
That sounded just crazy to me. Of course beef is aged, even for fairly long times, hanging in a refrigerated commercial refrigerator -- to age the beef, but I didn't think that applied to sitting in a supermarket shrink wrapped package in my refrigerator. (It's probably better to remove the steak from its package and re-wrap it to remove some of the possible sources of bacteria.)
Well I tried it, let a nice steak sit in my fridge for a week, then opened it. To be blunt it did have a mild unpleasant odor but it wasn't rank or anything. I cooked and ate it and I was amazed in the improvement in taste and tenderness! (The odor disappeared as soon as it hit the heat.)
These days I always visit the manager's specials and paw through what's there to see if there are any items I like. I know beef can go a week and don't even give it a thought -- if necessary I know it can go over a week. I'm not as sure about pork but I am having a stuffed pork chop for dinner tonight that I bought a few days ago. The stuffing is probably problematic and I wouldn't push it with steak. I won't buy chicken or fish unless it's to eat the same day.
I'm sure it's a good thing the FDA is over-protective than under-protective, and there are aesthetic considerations too. As I said a week after sell-by date beef could have a mild odor, and appearance can suffer too, turning somewhat grey.
That grey color is a farce anyway. The meat is treated with carbon monoxide to keep it from oxidizing which is what turns it grey. Untreated meat would probably turn grey within a couple days of being put on the shelves. I've never noticed the exact dating but my best guess is the butcher dates the meat to be sold with a sell-by date about a week after cutting and packaging.
My opinion is that beef is perfectly safe to eat at least 3 weeks after the butcher has packaged it, provided the butcher had sanitary equipment and the meat was kept at the proper temperature for the entire 3 weeks.