If you buy pickles in the refrigerated section of the grocery store, then it’s best to keep storing it in the fridge at home. But really most pickles don’t need to be refrigerated due to their contents.
The high salt and vinegar content in pickle jars is strong enough to ward off harmful bacteria and micro-organisms. Pickling something is actually a food preservation method, so your pickles should stay good for quite a long time.
Some foods are able to preserve themselves, like vinegar. It virtually has an indefinite shelf life. It’s recommended to keep vinegar in a cool, dark place, out of direct sunlight. A pantry or kitchen cupboard is perfect. This only goes for plain vinegar.
Others condiments, like vinaigrettes containing herbs, garlic, onion or other add-ons, may actually require refrigeration. If you are still questioning whether vinegar really has such a long shelf life, know that the Vinegar Institute did a study confirming such.
Due to ketchup’s natural acidity, it is inhospitable for microorganisms to grow and turn your ketchup bad. So, you don’t need to store it in the refrigerator. Lots of people do this, and many report that it has a better flavor at room temperature.
If you live in a particularly hot climate, then you might want to consider keeping your ketchup bottle in the fridge after opening. Or if you rarely use it, the fridge will increase its longevity.