'Can I Still Eat That?' How Long Your Favorite Foods Stay Edible

We’re going there—the back of the fridge—the place where you scrounge around after a hard practice, searching for something that will satisfy your hunger without a paper bag dripping with grease and “special sauce.” The back of the fridge can surprise you. There’s nothing quite like finding a slab of steak you’d forgotten. But if you're not careful, it can also sideline you.

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Spoiled food is something most amateur chefs have to deal with. At best, it could produce a yucky off-taste; at worst, it could make you very sick.

“The biggest cause of food spoilage is probably bacteria,” explains Joe O’Leary, Ph.D, professor of food science at the University of Kentucky. “We get some chemical, some enzymatic spoilage, but generally bacteria are the biggest cause of spoilage.”

The longer you let food sit in the fridge, the more bacteria are likely to be present in and on it. The more bacteria, the higher the likelihood that something could make you sick. Of course, if you’re like most people, you probably throw most of your food in the fridge to slow the growth of these bacteria.

“When you lower the temperature you slow the rates of chemical reactions and microbial growth,” O’Leary explains. “Lowering the temperature about 10 degrees centigrade will change the reaction rate about tenfold. Pasteurized milk, if you keep it in the fridge when you get home from the store, might keep about two weeks. If you let it sit at room temperature in summer weather, it might not even last two days.”

Spoiled food isn't always dangerous, but it's better to be safe than sorry. O'Leary says, "Spoiled food might be safe to eat, but might also be hazardous. Since we don’t know the cause of spoilage, it is best to pitch it."

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So about how long will some your favorite foods last before they spoil?

Poultry

Your leftover chicken breast should be on the menu before the end of the week if you want to keep it from going bad.

“If you have poultry in your fridge for a little over a week, the surface will become slimy and start to give off odors,” O’Leary says. “Slime is probably the most noticeable [sign that it has spoiled].” Of course, if you leave chicken sitting on your counter top, you’ve got considerably less time. “Generally, we don’t want things like meat left at room temperature for more than four hours,” O’Leary says. “It can become unsafe during that time period, even if it doesn't look any different.”

Shelf Life: A week in the fridge, a few hours on the counter.

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Beef

Ground beef and steak have different shelf lives.

“Ground beef will probably last about a week,” O’Leary says. “Steak, depending on how it’s packaged, that might be a couple weeks or longer. Some of this newer packaging for steaks and roasts will really extend its shelf life.”

Generally speaking, both ground beef and steak turn brown when they start to spoil. But since they come from different places and are handled differently during packaging, other indications may be different. O’Leary says, “Some of them will just change color, some will produce odors. Any time you produce odors in food, it’s a pretty good indication that it’s ready to spoil or already spoiled.”

Shelf Life: About a week for a cut of steak in the fridge. Four days for ground beef.

Bananas

Unlike the other foods on this list, you don’t want to put bananas in the fridge. They’re not meant to be in temperatures that cold, and the environment will prevent them from ripening correctly. As far as knowing when they’ve spoiled, it’s a personal preference.

“If you put them in a container, the ethylene gas will stay around them and they’ll ripen quicker,” O’Leary says. “If you leave them exposed and the temperature is [moderate], you can let them ripen to a nice yellow. I kind of like them when they’re just about to turn brown, as they’re a little sweeter then—but it’s a personal taste on what you like.” Of course, if you sniff a banana and it gives off a moldy, mildewy scent, that’s a good sign it's gone bad. You can also give it a squeeze: if it’s super mushy, it’s probably bad.

Shelf Life: Depends. A nice, yellow color and a firm texture (with a bit of give) indicate that it’s still good. Soft, brown and mushy are signs that its gone bad. And don’t throw these in your fridge!

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Apples

There are lots of different varieties of apples, but generally you get a few weeks out of them, assuming you left them out on the counter.

“Generally, around 50 degrees is an ideal temperature for apples, but it depends on the variety,” O’Leary says. “They’re quite different in how they react to temperature. [I would ballpark that most last] maybe a month.”

Of course, if apples are stored properly, they can last for months on end. Generally, this means a cool, dark place with little humidity. “When I was growing up in Ireland, we had a guy with an orchard nearby,” O'Leary says. “He’d pick apples in the fall, and he had an area where he stored them that was covered and below ground. They would keep until next summer.” Generally, an apple that has gone bad will be soft, mushy and brown.

Shelf Life: Depending on storage conditions, weeks to months.

Potatoes

You can stock up on this powerful source of carbs and hold onto them for months, provided you keep them out of the fridge.

“Too low of a temperature and you’ll get [the potato’s] starch converted to sugar,” O’Leary says. “Generally, you don’t want them refrigerated. Around 55-60 degrees Fahrenheit is the ideal temperature.” O’Leary says when potatoes were harvested in his home in Ireland, they’d last from the fall to the next summer with no problem: “We would generally harvest potatoes in the fall and we’d have them until the new crop came in next May. We’d keep them over six, nine months. They’d still be good.” Generally, a spoiled potato becomes soft and discolored. Potatoes may also sprout if you leave them unattended, but his doesn’t mean they’ve gone bad. Just remove the sprouts, and they’re still good to eat.

Shelf Life: Provided you’ve stored them in a cool, dark place, potatoes last quite a long time—maybe even six months. On your counter top, they will probably last at least two weeks.

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Eggs

Another staple in an athlete's diet, eggs can be tricky to judge until you’ve cracked them. If you get a rank smell, you know you’re in trouble.

“If you get a sulfide odor, they’re definitely spoiled,” O’Leary says. Stored in your refrigerator, eggs will last around a month. Any longer and you risk encountering dangerous stuff. “Eggs are much more likely to be contaminated with things like salmonella,” O’Leary says. “Today, we generally refrigerate our uncooked egg products. They need to be held at a low temperature.”

Shelf Life: About one month in your fridge.

This article originally appeared on STACK.com: 'Can I Still Eat That?' How Long Your Favorite Foods Stay Edible