From eggs to ketchup to pickles, a lot of stuff in our shopping bags bears that well-known phrase “Refrigerate after opening.” But as our fridges become overstuffed, it’s only fair to ask: Do all these things really need to live in cold storage? If you’ve ever visited friends in another country and seen how many of their foods sit out at room temperature, you might legitimately wonder if Americans are refrigerator crazy.

The quick answer is yes … and no. We’ve already seen why refrigerating bread is not the best option, and if eggs really need to chill. What about other foods?

First, it helps to understand the different kinds of bacteria that occur in refrigerated foods. According to the USDA Food Safety and Inspection Service’s guide “Refrigeration and Food Safety,” there are two: pathogenic bacteria that lead to food-borne illnesses, and spoilage bacteria that change the way food looks, smells, and tastes. When food develops dangerous levels of pathogenic bacteria, it could look, smell, and taste normal while still being dangerous. But when spoilage occurs, something can taste gross but won’t necessarily make you sick.

So let’s talk about specific foods that don’t need refrigeration. Condiments like fish sauce, soy sauce, and hot sauce do not need to be refrigerated—they contain enough natural preservatives to be just fine at room temp. The fridge actually changes the texture or flavor of some foods that should never have a home there: potatoes (starches turn to sugar, yielding an off flavor), tomatoes (they get mushy quicker), honey (it gets too thick), and onions (they soften, and leach onion-y scent onto nearby foods). All oils (except for volatile seed or nut oils like sesame and hazelnut—these quickly turn rancid at room temp) can be stored in the pantry, since cold storage makes them cloudy and thick.

There are foods that fall in the middle; it’s fine to keep them at room temperature, but it might change their quality or shelf life. An open bottle of ketchup is good for a month in the pantry, six months in the fridge. Peanut butter is just fine in the cupboard, but natural peanut butter lasts longer in the fridge. Real maple syrup can be kept out, but if you don’t use it very often, the fridge will prevent mold from growing.

A great resource for specific foods is the website StillTasty. Type in the food you have a question about, and using various sources (USDA, U.S. Food and Drug Administration, state government agencies, and food and beverage manufacturers, to name a few), you’ll get a clear answer in seconds.

Got a Nagging Question about food you're dying to have us answer? Leave it in the comments.

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