Why do processed meats spoil so quickly?

It's an otherwise normal Thursday evening, except for the fact that you added an hour to the end of your workday, got caught in traffic on the way home and then vowed to scrounge through the refrigerator for supper because you refused to spend the little free time you had left wandering through a grocery store.

It seemed like a decent plan until you actually inspected the contents of your kitchen's cold storage. A few baby carrots, some ancient hummus in a plastic takeout container, a tomato and — aha! — half a package of raw bacon. It wasn't that long ago that you were whipping up BLTs for the whole gang, so this bacon should still be edible, right? Upon closer inspection, you're not so sure ... it's a suspicious shade of tan, and it doesn't quite smell right, either.

Why does processed meat spoil so quickly? If it didn't, you'd already be well on your way to a plate of crispy bacon. If only you had some leftover meat that wasn't processed. After all, unprocessed meat keeps longer, right?

Wrong. Unprocessed meats, like sliced turkey, chicken cutlets or steak, have a shelf life of three to five days when raw or freshly cooked. Processed meats, on the other hand, can last several weeks in the refrigerator. Hot dogs, for example, can hang out in the refrigerator for two weeks if unopened and one week if opened. Lunch meat has a two-week safe zone when refrigerated in its original packaging, but it should be eaten within five days if the packaging is opened or if it was purchased from a deli [source: Meat Safety].

So, what qualifies as processed meat? The bacon on your morning bagel, the pastrami on your late-night sandwich — any meats that have been preserved by smoking, curing, salting or adding chemicals fall into the "processed meats" category. This includes deli lunch meats that have a casing or that have been compressed into cylindrical form, as well as ham, sausage, hot dogs and cured pork chops. In general, meats compressed into neat shapes designed to fit on bread or buns are processed.

While processed meats remain edible longer than fresh meats when stored in your refrigerator, it's still a good idea to consult the "best by" dates on the packaging. These guidelines will let you know when the meat is safe to eat and when it's no longer edible. Any meat — processed or not — poses a risk if consumed when outdated.