Mustard is perhaps one of the oldest condiments in the world. In fact, the ancient Roman cookbook De re coquinaria (Latin for “on the subject of cooking”) contains several recipes for a sauce remarkably similar to the classic condiment we know today. So you would think by now there would be an agreed-upon way to store it. To settle the debate once and for all, we reached out to the French’s team for an official answer, and it turns out that, yes, you do need to refrigerate opened mustard.
Like the ancient recipes, nearly every mustard available in stores contains vinegar or wine. This isn’t simply to enhance the flavors of the other ingredients but also because vinegar and wine have low pH levels, which means they are highly acidic. And it’s this high acidity that acts as a natural food preservative by inhibiting the growth of bacteria that can cause spoilage. That’s also what makes mustard so shelf-stable and why it’s typically not sold in the refrigerated section of supermarkets. But once you bring it home, you’ll want to be careful with how you store it—especially once you break the seal.
How to Store Mustard, According to French’s
If you don’t plan on using the unopened mustard right away, it’s fine to keep it out of the fridge—just make sure to store it the French’s recommended way. “Keep unopened mustard at room temperature [and] away from light,” says Hadar Cohen Aviram, executive chef and senior manager, culinary development, U.S. consumer, McCormick & Company. “These might cause it to lose flavor faster.” Aviram also says to look for the “Best By” date stamped on the bottle and use it up before then in order to enjoy the optimal level of the mustard’s flavor.
Once the mustard’s open, French’s recommends storing it in the refrigerator—a protocol that goes for all of their mustard products, including brown and Dijon variations. “The cold, dark environment will keep freshness at its best,” says Aviram. But not just any place in the fridge will do—and it’s not on the door like many may think. For maximum preservation, store mustard at the back of the bottom shelf, which is usually the darkest, coolest place in most refrigerators.
Why Storing Mustard in the Fridge Is Best
If you’re wondering how keeping mustard in the refrigerator helps keep it fresh, it turns out that there’s a simple scientific explanation. “The rate of oxidation increases as exposure to light and heat increases,” says Aviram. “Oxidation is a reaction that happens in foods that are exposed to air (think browning of sliced apples, crackers going stale and oil going rancid). Cool, dark environments slow down oxidation, therefore maintaining freshness, [flavor and color].” This also explains why many mustard products are packaged in thick, opaque plastic bottles.
On the contrary, Aviram says that mustard stored in a warm environment, or in direct sunlight, can oxidize at a faster rate. In other words, it may lose its freshness, flavor and color more quickly.
Tips from the French’s Team
Though storing mustard in the refrigerator is the best way to preserve it, many people simply don’t enjoy the taste of cold mustard—particularly when used to top a warm dish. Because mustard won’t spoil as quickly as other condiments—like mayonnaise and creamy dressings—Aviram offers this pro tip: “We know some of our French’s fans do not like cold mustard. [For] mustard lovers who prefer their condiments at room temperature, start your meal prep by portioning out the desired mustard amount into a small bowl to allow it to temper. By the time you’ll need the mustard, it’ll be at room temperature.”
This next piece of insider intel might surprise even the biggest French’s mustard fans, but it will also likely solve a problem many face—and that’s keeping the attached cap out of the way while squeezing out the mustard. “Did you know French’s yellow mustard cap allows you to pull it all the way back until it ‘clicks’? 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,” says Aviram. Protecting the condition of the cap just got a whole lot more important.
The Bottom Line
To sum things up: It’s OK to keep unopened mustard out of the fridge—just make sure to use it up before it expires. Once opened, keep it in the fridge to preserve its freshness, flavor and color. If you prefer room-temp mustard, portion out a small amount in advance. And always make sure to pull back the cap until you hear a “click” to ensure a smooth flow and to keep the cap from getting crusty.