Can Peanut Butter Go Bad? Here’s the Scoop.

Can peanut butter go bad? How do you know if it's no good? We'll tell you how to identify funky PB.

You reach into the pantry and find a jar of peanut butter that’s been sitting there for, well, who knows how long. After taking a peek at the best-by date (you’re in the clear!), you open the jar and stare into an ocean of oil. The peanut oil has separated from the solids during its long sit, which makes you wonder if it’s safe to eat.

Actually, it makes you question whether peanut butter is one of those foods you never knew had an expiration date!

Can peanut butter go bad?

Yes, it can go bad. But separated oil isn’t a sign of expired peanut butter. Natural peanut butter doesn’t contain additives, stabilizers or hydrogenated vegetable oils, all of which keep the peanut solids and oils together. The oil on top is actually a sign that you bought a high-quality peanut butter!

(Psst: There’s a genius tip to prevent this kind of separation, and it kind of changed my life.)

It’s hard for peanut butter to spoil because it’s mostly fat—that’s what makes it taste so good. Natural peanut butter only contains peanuts and sometimes salt, and while some nut butters also contain oil, sugar or stabilizers, there’s nothing there to add any water. This gives peanut butter its extremely low moisture content.

Since the majority of spoilage comes from microorganisms that grow in water, unopened peanut butter can happily sit on your shelf without going bad for a long, long time.

How do you know if peanut butter is bad?

You won’t find mold growing on it, but its high fat content means it can go rancid. (That’s the same reason we don’t recommend buying cooking oil in bulk.) Oxygen is the enemy here, and exposure to air can cause your peanut butter to develop off flavors. Rancid foods won’t kill you, but they also don’t taste great, either.

A sure sign of rancid peanut butter is a change in texture—perhaps it used to be soft and creamy, and now it’s dry and hard. It may also look darker in color or it might smell funky (sharp, bitter, soapy or metallic odors are a giveaway).

How should you store peanut butter?

To keep your peanut butter safe and fresh, it’s best to store it in the refrigerator. This is a requirement for natural or homemade peanut butter since these varieties lack preservatives. Once opened, it should last five to eight months past the best-by date.

If your peanut butter has been in the fridge for a while, it might be time to create an excuse to eat more peanut butter!

Have extra PB in the pantry? Find a recipe for dessert
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Lindsay D. Mattison
Lindsay has been writing for digital publications for seven years and has 10 years of experience working as a professional chef. She became a full-time food writer at Taste of Home in 2023, although she’s been a regular contributor since 2017. Throughout her career, Lindsay has been a freelance writer and recipe developer for multiple publications, including Wide Open Media, Tasting Table, Mashed and SkinnyMs. Lindsay is an accomplished product tester and spent six years as a freelance product tester at Reviewed (part of the USA Today network). She has tested everything from cooking gadgets to knives, cookware sets, meat thermometers, pizza ovens and more than 60 grills (including charcoal, gas, kamado, smoker and pellet grills). Lindsay still cooks professionally for pop-up events, especially when she can highlight local, seasonal ingredients. As a writer, Lindsay loves sharing her skills and experience with home cooks. She aspires to motivate others to gain confidence in the kitchen. When she’s not writing, you’ll find her cooking with fresh produce from the farmers market or planning a trip to discover the best new restaurants.