Should Mustard Be Refrigerated? You Might Be Surprised by the Answer

Whether your go-to mustard is classic yellow, Dijon, spicy brown, stone-ground whole grain, or a variety mixed with honey, horseradish, or even cranberries, proper storage is critical to making the most of this versatile condiment. We talked to chef Brandon Collins, one of the only mustard sommeliers in North America, to find out if mustard should be refrigerated or stored in the cupboard. Collins also provided some guidance on how long mustards last and how to preserve their flavor for as long as possible.

"Ideally, mustard should be kept in the fridge, at least after opening," Collins tells Hunker. But that's not to say it will go bad if you leave it out. "Mustard by nature is antibacterial, so therefore, it is shelf-stable. When you add vinegar, salt, etc., it helps to extend the shelf stability," he says.

Ultimately, like Sriracha, mustard never really spoils in the sense that it will taste rancid or make you sick. Still, Collins notes, "Once air, water, and vinegar hit the mustard seeds, they start to release their 'heat,' which is not reversible; it can only be slowed down."

Because mustard doesn't go bad in the traditional sense, bottles and jars are usually labeled with a "best-by" date rather than an expiration date. That best-by date is there to let you know that the product will start to lose its flavor and potency by that point, even when it's been kept in an unopened, sealed container.

Technically, mustard can last indefinitely, but it won't have much flavor after a while. For maximum potency, use mustard by the best-by date on the bottle. After opening, refrigerate your mustard to preserve its flavor and eat it within six months to enjoy it the way it was intended to taste, rather than a dulled, aged version. "Though it is shelf-stable, it should still be kept in the fridge after opening to prolong the complexity, heat, and flavor," says Collins.

Those who prefer room-temperature mustard can leave it unrefrigerated, but they should try to eat it within one to two months to maintain the flavor profile as much as possible.

If you don't eat your mustard within the recommended time frame, Collins says that you can keep it longer — but only "if you are fine with the flavor loss."

Not really. All mustards should be kept in the refrigerator after opening to keep them tasting their best. Of course, strong, spicy mustards may still taste good longer than those with a more mild, subtle flavor profile.

Though mustard itself might not go bad, bits of bread, swirls of mayonnaise, and other contaminants embedded in your mustard can become hotbeds of bacterial growth. "While mustard itself will prevent a lot of things from growing in it, as you start to add foreign ingredients, there will be a level at which mustard cannot prevent growth," warns Collins.

To avoid contaminating your mustard with other foods, use a clean utensil every time you scoop it out. Avoid spreading it on your sandwich and then using the same knife to get more mustard. Collins says, "If you think there could be cross-contamination, always make sure to put it into the refrigerator." Remember that when cross-contamination occurs, refrigeration becomes a food safety issue rather than simply a matter of taste.