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? Here are some tips.

    Ketchup It can remain at room temperature. 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, according to Benjamin Chapman, associate professor and food safety extension specialist at North Carolina State University.

    Eggs Your safest bet is refrigerating your eggs. Eggs may carry 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.

    Butter For better or for worse, butter is mostly fat. Only a small portion is actually dairy, which is typically pasteurized, explains microbiologist Angela Winslow, 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 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, 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. The exception: Cut lemons and limes are acidic enough to fend off bacteria when left out.

    Mayonnaise 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 growing bacteria all by itself. 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.

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

    Cheese It depends. Hard cheeses can last for quite a while unrefrigerated. That’s because their water content is low and bacteria rely on water to grow. However, cheeses with high moisture content should be refrigerated.

    When in doubt, always opt for storing your foods in the fridge.

    Even if you store all of your food in the fridge, you probably still need to turn down the temperature. It’s safe to see them set below 5 degrees Celsius.

    (SD-Agencies)