
You know what, I’m taking a side here: if it’s open, put it in the fridge. But not bread. Or apples. Or red wine.
Okay, I’m back on the fence.
Of course, as soon as you open a perishable and it’s exposed to the air, various bacteria have got all they need to start multiplying on your grub. Some condiments’ preservatives will keep them at bay for a while, but they’re slowed down even more in cold environments.
If only it were as simple as that. Plenty of people opt to keep their ketchup in the cupboard without getting ill from it – at least, as far as I know – and so no amount of science is going to convince some people to change their ways.

Science might fail to win people’s trust on the matter, but what about a brand?
When it comes to mustard, one of the biggest names in the game is French’s. With its bright yellow packaging, delicious and tangy mustard, and shapely bottles that give your fridge (or cupboard) a little bit of diner flair, it's a firm favourite for many of us.
Wading into the fridge vs cupboard debate is Hadar Cohen Aviram, Executive Chef for US Consumers at French’s parent company, McCormick & Company.
For Aviram, the answer as to where to store your mustard is pretty cut and dry.
“Keep unopened mustard at room temperature away from light,” she told Simply Recipes.
“Make sure not to store it in high temperatures or under direct light — these might cause it to lose flavour faster.”
Once it’s opened, guess where Aviram reckons it should be stored.
“The cold, dark environment will keep freshness at its best,” she said. “Try not to leave it out for long stretches of time—remember those high temps and light exposure? It'll make the mustard lose its flavour faster!"
While you’ve likely seen many a mustard bottle left on a counter at a restaurant or burger van, it’s the aforementioned preservatives that prevent it from spoiling as quickly as something like houmous or tzatziki.
The high acidity levels in mustard don't make for a great environment for bacteria, so it does mean you’ve got some wiggle room if you’re absolutely committed to telling fridge-storers where to go.
If you’re a little more sane than that, then surely Aviram’s got you convinced. No? Fine.
For both the fridge and cupboard faithfuls, the tests as to whether your mustard is past its best are the same.
When you give it a taste and the flavour’s become more mellow, it’s probably time to throw it out.
Aviram also said it’s best to keep the cap firmly affixed between uses and to consider it to be game over if you accidentally break it.

“French’s yellow mustard cap allows you to pull it all the way back until it clicks,” she said. “This helps keep the consistency of French’s mustard that fans know and love while avoiding those crusty bits. The end result is the perfect squeeze with the utmost convenience.”
If any of this advice has stirred up some righteous indignation in you, feel free to meet me outside the saloon at high noon with a fully-loaded bottle of mustard so we can settle this like men.
Featured Image Credit: Howard Kingsnorth/Getty Images