Since the dawn of time -- or at least the invention of the refrigerator -- there have been heated debates about whether certain sauces, condiments and spreads should be kept in the fridge or pantry.

Ketchup belongs in the fridge, right? And peanut butter in the pantry? Well, it depends who you ask.

Is "refrigerate after opening" a rule we really must abide by? Or is it more of a gentle suggestion?

Well, luckily, NYT Cooking recently published an A-to-Z guide to storing condiments -- and food columnist Eric Kim is here to walk us through the highlights.

Shelf-stability depends on your use. Because of the acid and salt content in condiments, most of them are shelf-stable, so long as you don't let moisture in.

It all comes down to moisture content. Water makes things spoil because it promotes bacteria, and pH level affects how bacteria grows. The lower the pH, the longer it lasts. Science!

Pantry, but after 2 to 3 months, it should go in the fridge. The National Peanut Board says 3 months after opening, the natural kind should be in the fridge. I'm a Skippy guy so I know that the not-so-natural kind does not need to go in the fridge ever.

Fridge. But if you're going to bake, then it's OK to leave it out for a day or two on the counter. People don't always know what bakers mean by "room temp." When we say room temp for butter, we mean take it out overnight -- you won't get sick!

My personal opinion is if you want to preserve that flavor, fridge. Food that is cold stays fresher longer -- that's not something new. Assuming you aren't going through a bottle of hot sauce a week, that cold will keep the flavor stronger for longer.

Fridge! It'll stay fresher for longer.

Fridge. If you leave it in the pantry for too long, much like mustard seed or any dry spice, it eventually loses its flavor. It's not that you will get sick, but it just won't taste as good.

Pantry. But for this it should be in a cool, dark place because light actually breaks down particles within the oil and makes it taste not as good. That's why olive oil bottles are often dark glass.

There's one kind of oil I do put in the fridge -- sesame oil. Seed oils go rancid so if you're not using it regularly it should go in the fridge.

This should go in the fridge after opening, but honestly, I've always kept it out because it's so salty and preserved, so I think it's fine on the counter. But its flavor will last longer in fridge.

Refrigerate after opening. Before you open it, it's been sealed off from moisture or bacteria that can go in there. Once you open the jar, you're letting in these external factors that we don't realize are getting in.

Part of it has to do with separation of the oil -- if your counter is hot in the summer and you leave mayo on the counter, the oil and egg yolk will actually separate.

Fridge. Pure maple syrup is a natural product -- maple water sap that's been reduced. If you leave it out on the counter too long, it can firm up. It's a precious liquid so needs to be in the fridge.

But the "fake" kinds can definitely be left in the pantry.

Definitely pantry. If you put it in the fridge, it'll solidify. Honey has antibacterial properties, so you can leave out. It lasts forever.

Sometimes the top gets crusty because of the crystallization of sugar. If that happens, warm the bottle in a water bath.