In 2011, just before the start of the winter holidays, Norwegians suddenly found themselves facing an immense, pressing crisis: a nationwide shortage of butter. A combination of factors gave rise to what became known as smør-panik, including summer weather patterns that curbed milk production, the emergence of a high-fat diet fad, and Norway’s lofty import tariffs on butter from other countries. As a result, Norway’s butter prices climbed up to the equivalent of $50 for 250 grams, or just over half a pound. The country’s dairy drama captured the world’s attention as butter smugglers were arrested, and butter shortage memes were made.
In the end, Norway’s citizens—and their cakes—made it through the panic unscathed, and butter prices have since stabilized. If this cautionary tale makes you want to stock up on a few (dozen) pounds of the stuff before cookie-baking season arrives again, here’s what you need to know about keeping your supply as good as new.
What is it, exactly?
Butter is a product of milk, which itself is a mixture of fat, water, proteins, and minerals. As anyone who’s overwhipped a bowl of cream should know, all it takes is a little agitation for the butterfat to separate from cream’s other components, collectively known as buttermilk. Butter produced in the United States legally must contain at least 80% fat, but imported and premium butters can reach between 85% and 90% fat.
That combination of high fat content and low water content is key to butter’s long shelf life. As Harold McGee writes in On Food and Cooking, “Because its scant water is dispersed in tiny droplets, properly made butter resists gross contamination by microbes, and keeps well for some days at room temperature.” (Read More: What Is Butter? A Comprehensive Guide)
Does butter spoil?
Sure, butter can spoil, but usually only under extreme conditions by today’s standards. Salt was originally added to butter as a preservative before the advent of refrigeration; in modern times, however, it’s really only used for flavoring. But even unrefrigerated butter can keep well for several days.
“It’s pretty rare to have butter go bad, unless you’re leaving it out for weeks at a time on the countertop,” says Hilary Haigh, co-owner of Vermont’s Animal Farm Creamery. She and her husband, Ben, purchased Animal Farm earlier this year from Diane St Clair, who taught the Haighs the hand-crafted techniques that made her unsalted, cultured butter one of the most sought-after dairy products in the US. (The preferred butter of Thomas Keller’s Per Se and The French Laundry, Animal Farm butter is usually only available to the general public once a year, when it retails for $60 per pound through Saxelby Cheesemongers.)
“I feel like you really have to abuse it in order for it to spoil,” Haigh tells me. “It’s more often that it takes on the odor of something else—like if you used a knife that you chopped some garlic with and you grabbed a scoop of butter with it, then that whole package of butter that was exposed to that knife is then gonna taste garlicky.”
Of course, butter’s remarkable ability to absorb flavors can be a good thing too. It’s precisely why compound butters are such effective delivery vehicles for the otherwise fleeting flavors of ingredients like truffles and fresh herbs.
McGee writes, however, that exposure to air and bright light can negatively affect the flavor of butter, causing its fat molecules to taste stale or rancid. Air can also dry out the surface of butter, leading to dark, unpalatable patches. They won’t make you sick, but they should be removed for better flavor and texture.
It’s worth noting that clarified butter or ghee—which has been cooked and filtered to remove its protein and water content—can last even longer than conventional butter: up to six months at room temperature and a year (or possibly even more) in the fridge. Regardless of how you store it, it too should be kept away from light and air.
Can I freeze butter?
“I don’t know why people freeze butter,” Haigh says with a laugh, “but it definitely does freeze fine. If you were trying to stock up on a butter sale somewhere, or if you bought a pound and realized you weren't actually gonna use it for a few weeks or more, then you might just throw it in the freezer.”
She adds that butter should stay perfectly fine in the freezer for up to six months, and the only thing to worry about is freezer burn—so remember to keep it wrapped tightly to prevent exposure to dry cold air. As with other dairy products, however, it’s best to simply buy only what you need and use it up promptly. Especially when it comes to high-end butters, time will only dull the delicate aromas and flavors of the cream.
While it’s not common in Western kitchens, intentionally aged butter is indeed a thing. North African cuisines prize a long-fermented butter called smen (سمن), which is used to flavor tagines and rfissa, a Moroccan chicken-and-lentil dish. In the old medina of Fes some years ago, I met a smen seller who cracked open a plastic blue barrel—buried to its top in the ground to keep it cool—and offered me a taste of the salted and intentionally rancid butter, which was grainy and tasted like a particularly powerful Gorgonzola.
Does butter need to be refrigerated?
You don’t need to refrigerate butter, just as you don’t need to salt your pasta water. (As a fellow food writer often says to me, “It’s food—do whatever you want with it!”) Your mileage may vary, but the US Department of Agriculture recommends that you leave butter unrefrigerated for no more than two days, after which its fat content can turn rancid and take on unpleasant flavors. This won’t make you sick—but it won’t taste creamery-fresh either.
As for how long butter keeps under refrigeration, there’s no consensus, really. USDA says butter will stay good between one to three months in the fridge, while our friends at Bon Appétit say it’s more like four months. Butter’s shelf life is mainly a question of flavor and texture rather than spoilage, so follow your senses and simply throw it out if it tastes unpleasant to you.
To extend the lifespan of butter, McGee suggests storing it in its original foiled or waxed paper, if that’s how it came when you bought it. If that’s not an option, stick with plastic wrap or baggies, always keeping the butter airtight in its wrapping. (Aluminum foil can hasten oxidation, so it’s best to avoid.)
And what about covered butter dishes and butter bells? Both protect butter from drying out, and neither works significantly better than the other—it’s merely a matter of aesthetics and personal preference.
Haigh tells me that she keeps her $60 butter in something even more utilitarian. “I actually just use either a mason jar with a lid or a Pyrex with a lock-type lid that really seals the container completely. I end up just taking it out of the fridge in the morning, and it softens up so that I can spread some on my toast. And then when the family’s done with it, I put it back in the fridge and it stays there until I need it again, because all butter is best at room temperature.”
All in all, Haigh says, spoilage shouldn’t be a concern when it comes to butter. “Butter is such an amazing product,” she says. “Rarely does it ever grow mold or spoil in the way that a loaf of bread does or a gallon of milk does.”
