There are two types of people in this world: those who store ketchup in the refrigerator and those who don't. It might seem like an innocuous distinction, but it's actually a heated debate, and folks have strong feelings on both sides. One Twitter user even went so far as to call someone who stores ketchup in the pantry "an animal" (which, to me, seems like an overreach, but hey, we all have our priorities). But who's right? Do you need to refrigerate ketchup, or can you just leave an already opened bottle of ketchup hanging out on your kitchen counter?

Unfortunately for those looking to be proven right, there doesn't seem to be a totally correct answer to this one. Whether you should refrigerate ketchup or not depends on a bunch of different factors, starting with which brand of ketchup you buy. And most manufacturers do recommend that you refrigerate your ketchup for best results. For instance, Heinz ketchup is technically shelf-stable because of its "natural acidity," though the manufacturers add, "its stability after opening can be affected by storage conditions." Sir Kensington's all-natural ketchup, meanwhile, has no preservatives, so the manufacturers recommend always storing an opened bottle of their ketchup in the fridge for up to two months.

But according to a totally unscientific Twitter poll conducted by British supermarket chain ASDA, 54% of respondents keep their ketchup in the cupboard. So are those folks storing ketchup totally wrong by ignoring the manufacturers' instructions?

Not necessarily. It's safe to keep ketchup in the pantry because, "The vinegar and tomatoes in ketchup give it a high level of acidity, which slows down bacterial growth," explained microbiologist Dr. Peter Barratt told the Daily Mail. And as Lauren Feingold, a culinary and nutrition expert, told NBC's Today, you can store ketchup unrefrigerated for up to a month, especially if you're going through it quickly. (For what it's worth, Dr. Barratt's estimate is a bit shorter than Feingold's: only two weeks, as compared for four.) Even the US Department of Agriculture's Food Safety and Inspection Service 

So sure, keep storing ketchup in your pantry. But if you're an infrequent ketchup user or want your ketchup to stay as high-quality for as long as possible, you're better off putting it in the fridge.