Do You Really Need to Refrigerate That?

Do you really need to keep ketchup, eggs, or cheese in the refrigerator? If you’re scant on space, here’s what’s safe to clear out. (Photo: Radius Images/Corbis)

You buy pickles in the non-refrigerated foods section of the grocery store, yet keep them stored in your fridge. Ditto with the ketchup. And all your produce, for that matter. Before you know it, your fridge is packed to the gills — but how much of that stuff really needs to be kept cool to remain safe for consumption?

Yahoo Health talked to the experts to find which of these in-between foods need to be refrigerated, and which are OK to hang out at room temp:

Ketchup: Can remain at room temperature.
Ever wondered why restaurants keep ketchup on their tables rather than back in the fridge? Because it won’t make you sick, says Benjamin Chapman, PhD, associate professor and food safety extension specialist at North Carolina State University. Ketchup is so acidic that it prevents the growth of harmful bacteria. It will spoil faster if left out on the counter, but it could still take months to turn bad. And, even when it does, it won’t hurt anything but your taste buds, Chapman tells Yahoo Health.

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Eggs: Must be refrigerated.
If you’re reading this in the U.S. of A., your safest bet is refrigerating your eggs. Somewhere between one in 10,000 and one in 20,000 eggs in the U.S. carries salmonella. Refrigerating your eggs is one of the best ways to prevent the growth of the food-borne pathogen, Chapman says, since salmonella bacteria love to grow at room temperature. So why do people rarely refrigerate them in some other countries? Because those countries have either a lower risk of salmonella (many European countries have gone to great lengths to eliminate the bacteria) or worse food-borne illnesses to worry about, he says.

Butter: Can remain at room temperature.
For better or for worse, butter is mostly fat. Only a small portion is actually dairy, which is typically pasteurized, explains microbiologist Angela Winslow, PhD, a research associate with the Joint Institute for Food Safety and Applied Nutrition. “From a food-safety standpoint, as long as it is contained properly, [butter] will not grow any harmful bacteria since there is very little moisture content present,” Winslow says. “The salt content also would reduce the incidence of bacterial growth.”

Fruits and vegetables: It depends.
If you think about it, fruits and vegetables grow outside at temps far higher than room temperature. That’s why, when they are whole, they are safe on your counter. However, when you cut them (or in the case of lettuce, just tear their stems from the ground), you actually rip open the cells of the plant. This releases nutrients, water, and bacteria, and allows them to mingle with each other, says food microbiologist Donald W. Schaffner, PhD, distinguished professor at Rutgers University. For example, when you cut a tomato or avocado, you need to keep it in the fridge to prevent the growth of salmonella. However, it’s worth noting that listeria can grow (albeit slowly) at cold temps. That’s why, even if you keep cut melons in the fridge, you should throw them out or add them to the compost pile after four days, Chapman says. The exception: Cut lemons and limes are acidic enough to fend off bacteria when left out.

Mayonnaise: Must be refrigerated.
Well, this one is really more of an “it depends,” but we’re going to suggest sticking it in the fridge just in case. Most store-bought mayo is acidic enough to keep on the counter without it growing bad-for-you bacteria all by itself. (That’s why fast-food joints can keep it out in pumps until it’s used up.) But, if you cut some veggies with a knife, and then stick that knife in your jar of mayonnaise, you could potentially introduce bacteria into the mayo that is able to grow at room temperature, Chapman says. Meanwhile, whatever the recipe, homemade mayo is generally not acidic enough to fend off pathogens.

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Pickles: Can remain at room temperature.
They make you pucker for a reason: They are acidic, and acidic environments are not suitable for the growth of food-borne pathogens, Winslow says. Sure, some forms of bacteria are OK with acid, but they aren’t the kinds that will make you sick to your stomach, Winslow adds.

Mustard: Can remain at room temperature.
Like pickles, mustard is acidic enough that you can leave it on the counter without worrying about food-borne illness, Chapman says. Plus, most mustard is relatively high in sodium, and salt’s a pretty powerful pathogen preventer.

Maple syrup: Can remain at room temperature.
“It’s basically pure sugar — there’s not anything that could grow in it that would be of concern from a food-safety standpoint,” Chapman says.

Cheese: It depends.
“I once saw a supermarket selling mini-packaged hard cheeses at the register unrefrigerated. One customer commented and complained that they could not sell it because on the package it reads that it should be refrigerated. While true, hard cheeses can last for quite a while unrefrigerated,” Winslow says. That’s because their water content is low and bacteria rely on water to grow. “Does that mean that I do not refrigerate my sharp cheddar? Not necessarily. However, if I left it out overnight or even for a few days, I would not throw it away,” she says. However, cheeses with high moisture content should be refrigerated.

Disclaimer: When in doubt, always opt for storing your foods in the fridge. It’s a good “just in case” measure that can’t really backfire from a food-safety perspective, Winslow says. But even if you store all of your food in the fridge, you probably still need to turn down the temp. “We know that refrigerators often aren’t cold enough to prevent pathogen growth,” Chapman says. “We want to see them set below 41 degrees Fahrenheit, but research shows they generally are above 45 degrees.” He recommends buying a refrigerator thermometer in the kitchen section at your local department store.

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