Food and Nutrition

How To Tell if Your Peanut Butter Has Gone Bad (Because It Probably Has)

Photo: Stocksy/Mariela Naplatanova
A quality PB&J sandwich can quickly take you back to your childhood. Something about the slightly salty and nutty spread paired with a sweet and tart jam like strawberry or grape always hit the spot growing up. And honestly, nothing's changed; we will never stop reserving a special spot in our pantries for peanut butter. After all, what else will you reach for when you need a post-workout pick-me-up, an ideal hiking sandwich spread, or a midnight snack?

That being said, while some can go through an entire peanut butter jar in a week (h/t to parents with little ones), most of us actually take several months to reach the bottom of the container. All good, save for the fact that this spread spoils a lot faster than you assume.

Indeed, despite the fact that it appears to last virtually forever, peanut butter often expires within just a few months after opening or sooner. Here, we’ve gathered a few pointers for determining whether your creamy-slash-crunchy nut butter has spoiled or is still usable with indicators like smell, taste, and appearance.

Does peanut butter go bad? You bet. Here's how to check if yours has spoiled

As peanut butter contains minimal moisture due to its high fat content, a sealed jar of the spread can sit in the pantry for anywhere from six months to two years before spoiling if it's made with preservatives. However, an opened jar—which exposes the butter to microorganisms fueled by oxygen—can only last two to three months, depending on the type and how it’s stored. More importantly, an unopened jar of natural peanut butter (i.e. one made without preservatives) will last just six months maximum; once opened, it will likely start to turn rancid after just a month.

Why? Studies show that natural peanut butters made without oil, sugar, or stabilizers tend to have a shorter shelf life than those made with ingredients like hydrogenated, palm oil, or preservatives like sodium benzoate. Once an opened jar of nut butter begins to interact with environmental factors, its oxidative stability—free radical reactions between fatty acids and oxygen that cause rancidity—begins to diminish.

A jar of nut butter with low oxidative stability will begin to taste rancid, bitter, or pungent as time goes on. According to a study on the quality of stabilizer-free natural peanut butter during storage, natural PB kept at 10°C (50°F) began demonstrating loss in oxidative stability after just 12 weeks. Alternatively, when stored at higher temperatures of 25°C and 35°C (77°F and 95°F, aka closer to a kitchen's room temperature), the stability shortened to only four weeks.

Aside from the pungent taste of rancid peanut butter, the spread will also emit a foul odor. If the butter gives off a bitter, metallic, or soap-like scent, it is time to part ways. Additionally, if the color darkens, the texture becomes dry, or there are signs of mold growth, the peanut butter has gone bad. However, don’t be alarmed by natural oil separation; it’s completely normal and a sign of good-quality natural nut butter. And, of course, always check the expiration date to use as a point of reference.

How to store peanut butter so it lasts longer

Storing nut butters in a dry, cool environment can help them stay fresh for longer. Once opened—and if you don't expect to be using it up in the immediate future—simply place the jar in the fridge to reduce moisture exposure and bacterial growth, which will add months to its shelf life. If you see separation occurring between the solids and oils, flip the jar upside down when stashed away. This will help re-incorporate the ingredients once flipped back, right side up. You can also soften cold PB fast by simply leaving it out at room temperature for ten to 15 minutes.

You can also freeze peanut butter. Try these hacks for seamless spreading

If your household doesn’t consume peanut butter regularly and you’re looking for a way to cut back on food waste, freezing the nut butter will buy you even more time to use it up—think years. Transfer the contents of your opened jar of peanut butter to ice cube trays to freeze the spread in convenient chunks, then drop them into freezer bags.

Better yet, according to a viral TikTok video, you can also enlist your freezer to make the most perfect PB&J sandwich. The trick helps you avoid tearing the bread as you spread your glob of peanut butter by freezing thin layers of peanut butter on parchment paper for ready-to-use portions. In the video, Eitan Bernath explains that you should start by spreading a large amount of peanut butter on a sheet of parchment into a thin layer using a spatula. Then, cover the layer with another sheet of parchment paper and press firmly with your hands or using a rolling pin to smooth out the peanut butter into an even, uniform layer.

@eitanI think it would be much easier just to make it the old fashioned way...😂🍇🍞🥜 (IG: @EITAN) #food #cooking #recipe #peanutbutter #5minutacrafts♬ original sound - Eitan Bernath

Next, freeze the parchment-lined peanut butter on a flat sheet tray for at least half an hour to an hour. You can perform the same steps and freeze thin sheets of jam, too (though depending on the consistency, it may not freeze as well as the peanut butter). Once the spreads have completely frozen, remove them from the tray, and cut them into individual-sized portions. If making a traditional PB&J sandwich, cut the layers to match the shape of your bread. Lastly, carefully remove the parchment paper before assembling your sandwich. The result? A delicious PB&J sandwich, minus the torn bread (and more importantly, no expired peanut butter in sight).

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