Does Butter Go Bad?
Butter is made from fat and protein components of churned cream, and contains about 80% butterfat. It is difficult for bacteria to penetrate such a high amount of fat, but over time it can break down, says Michael Laiskonis, a chef at the Institute of Culinary Education.
"Over time (and when exposed to heat, light and oxygen) particles within the fat will begin to break down and create off-flavors and aromas," he says. "This is mitigated by refrigerating butter and making sure it is well wrapped." In general, butter kept in the fridge will last one to three months, while butter stored in the freezer will last up to a year.
What Do Butter's Sell-By and Expiration Dates Mean?
Different indicators on food packaging—sell-by, best if used by, use-by—have different meanings. These do not indicate safety dates for food, with the exception of infant formula, but indicate quality, according to the USDA.
A "best if used by" or "best before" date indicates quality, but your food will not be "bad" after the marked date. "Sell-by" dates are not safety dates, but indicate to grocers and retailers when the product should be rotated off the shelves. And a "use-by" date is the last date recommended by the manufacturer to use the product, also based on quality, not safety.
Other dairy products like milk, cream or yogurt (even dairy-free options) might not taste or smell good as these dates pass by, but butter doesn't always show signs of spoilage as immediately.
Related: Does Almond Milk Go Bad?
How to Tell If Butter Has Gone Bad
Laiskonis suggests letting smell and taste be your guide to determine if your butter has gone bad: "Sour or off-flavors are the common cue, as are discoloration, and obviously the appearance of any molds. I always recommend that if its quality and safety are ever in doubt, best to throw it out."
How to Store Butter in the Refrigerator
Butter often acts as a sponge, and can absorb the flavors and aromas of food stored near it even when refrigerated, which is why kitchen items like crocks and containers are popular options for creating an airtight seal around your butter.
Keep your delicate butter tightly wrapped in the original packaging for best results, ideally in the designated butter compartment to keep odors out and the freshness in.
How to Store Butter in the Freezer
If you've found yourself with too much butter on your hands, toss it in the freezer. Previously frozen (and properly thawed) butter can be used the same way you would use regular refrigerated butter.
Just like in the fridge, "wrapping well to avoid oxidation and flavor transfer is key," adds Laiskonis. Keep your butter in the original packaging and place it inside a sealable bag, or cut it into smaller quantities and wrap them individually before placing them into a sealable bag.
When it's time to use your butter, stick it in the fridge to slowly defrost for several hours. Or, try bashing smaller pieces with a rolling pin, baking pro Dorie Greenspan suggests. Microwaving is not a recommended technique, as it thaws your butter unevenly.
How to Store Butter on the Counter
There is a surprising amount of debate when it comes to storing butter in the refrigerator versus on the counter for daily use. Ultimately, pasteurized and salted butter can be kept in a proper storage container at room temperature to maintain the quality and integrity of butter.
But like in the refrigerator and freezer, butter can absorb flavors and odors when sitting on your kitchen counter, so it is not recommended to leave it sitting there for days on end.
The USDA's Food Safety and Inspection Service says it's fine to leave butter out overnight so it will be soft enough to spread the following morning. However, "If butter is left out at room temperature for several days, the flavor can turn rancid so it's best to leave out whatever you can use within a day or two," says FSIS.
If you enjoy readily spreadable butter and have the counter space, invest in a butter crock, a special type of butter dish that uses a water-filled base to create an airtight seal.
Do I Store Salted Butter Differently from Unsalted Butter?
The difference between salted butter and unsalted butter is obviously salt. Salt can act as a preservative for everything from meat to citrus, and does the same for butter to prolong the shelf life.
"Salt is a known preservative in foods since it reduces water activity in foods, inhibiting microbial growth and chemical reactions. Hence, salted butter lasts longer than unsalted butter," says Jennifer Chiongbian, a Culinary Institute of America-trained chef.
On the other hand, unsalted butter contains no added salt and using it in your favorite baked goods can help control just how much salt goes into your recipes. Since it is butter in its "pure" form, it will have a shorter recommended shelf life, but can still be stored in your refrigerator.
Ultimately, butter can still be eaten and used in recipes despite what the expiration or sell-by dates say. Venae Watts, a fifth-generation butter maker and co-owner of Ohio's Minerva Dairy, advises, "You can absolutely eat butter past the sell-by or expiration dates. Just be smart and do the two-step test: look and taste. The butter that passes is perfect to enjoy."
Now put that butter to good use, like in this recipe for Sautéed Broccoli & Kale with Toasted Garlic Butter or in this one for delicious, flaky biscuits.