Do I Need to Refrigerate Ketchup? An A-to-Z Guide to Storing Condiments
Soy sauce? Peanut butter? Maple syrup? Settle some scores with this breakdown.

You keep mustard in the fridge, but your partner (or roommate or dad) balks at the idea. Who’s right? The fine print on the bottle, on nearly all of the bottles — “refrigerate after opening” — isn’t much help.

Turns out, that urging is rarely about health risks and more about quality, said Abby Snyder, the associate professor of microbial food safety at Cornell University.

Dressings separate, bright sauces darken and fiery flavors fade, given enough time. Spoilage microbes might even get a foothold, making condiments and other ingredients unpleasant but not unsafe to eat. All of these processes are slowed or even halted in the fridge, but they’re already heavily inhibited by low levels of water (which bacteria need to survive) and high levels of their nemeses (salt, acid, sugar, active probiotic cultures or other preservatives).

So do you even need to refrigerate? “A good rule of thumb: If you bought it from the refrigerated section at the store, it should stay in the fridge at home,” said Carla Schwan, the director of the National Center for Home Food Preservation at the University of Georgia.

For everything else, other than a handful of examples below, consider your lifestyle. “If you use it often and it’s shelf stable, keep it in the pantry or on the counter,” said Lisa Cheng Smith, the founder of the Taiwanese pantry shop Yun Hai. “If you use it more rarely, put it in the fridge to make sure it stays in peak condition.”

A few other tips for making your condiments last: Keep shelf-stable bottles tightly sealed in a cool, dark, dry cabinet — not over the stove — as light and heat will speed up oxidation. (If you live somewhere hot and humid, you might need to move through them faster or keep more in the fridge.) And always use a clean, dry spoon or knife — no fingers — to avoid planting bacteria or the moisture they crave.

Below you’ll find everything you need — informed by food safety microbiologists, fermentation experts and the manufacturers and purveyors themselves — to help you make the call on 22 common staples, and set any debates to rest. (Yes, you can move the peanut butter to the cabinet now.)