On refrigerating ketchup

Do I have to refrigerate ketchup once it’s open?

We’ve both seen ketchup sitting out on diner countertops, so that must mean “no”. But on the other hand, those bottles probably get pounded empty and refilled with (refrigerated) ketchup every day… so maybe it’s not a perfect analogy for home-use.

Ketchup is one of those refrigerate-after-opening foods. Other foods in this group includes pickles, olives, most condiments and sauces.

These foods are sterilized during manufacturing which makes them shelf stable until they are opened. But once opened, you need to refrigerate them to slow down any bacteria that might have found its way in. 

Ketchup specifically is acidic enough to ward off every illness-causing bacteria except one*.  Keeping your ketchup in the pantry will definitely shorten the shelf life — it’ll probably become discolored or moldy at some point (weeks? months?) even if these things won’t make you sick.

But yeah, if you want to live on the edge or you have a very full refrigerator then ketchup can live in the pantry.

*Salmonella can technically grow in ketchup-level acidic conditions. But how on earth would Salmonella get introduced into a ketchup bottle in your home kitchen? If you can come up with an answer then you should probably refrigerate ketchup.

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