July 18, 2024

Peanut butter can go bad. Eating spoiled peanut butter can cause a variety of concerns ranging from a mild tummy ache to a severe case of salmonella. Be sure to store peanut butter in a cool, dark area in a tightly sealed container.

What could be more perfect than peanut butter? It’s creamy, crunchy ,salty-sweet, and can be stored at room temperature longer than many pantry food items. This nutrient-dense pantry staple is packed with essential vitamins, minerals and fats.

As an added bonus, peanut butter seems to last forever. But does it? Spoiler: It spoils.

Here’s a rundown of the risks of eating bad peanut butter, signs of spoilage, and how to maximize its shelf-life.

While peanut butter can last a long time, it can definitely go bad.

Peanut butter boasts properties that give it a very long shelf-life. It’s oily, high in fats, and has low levels of moisture. This makes it difficult for bacteria to grow.

Peanut butter’s shelf-life depends on the brand and if its natural or commercial. Here’s how long a commercial peanut butter with stabilizers should last:

  • 912 months in pantry unopened
  • 23 months in pantry after opening
  • 12 months in fridge unopened
  • 34 months in fridge after opening

Most name-brand peanut butters contain add stabilizers or preservatives to further the shelf life. This includes:

These stabilizes are also used to enhance the creamy texture, prevent oil separation in the jar, and further deter the growth of bacteria.

Just like any other food, once the packaging is opened, the food is exposed to environmental elements.

Peanut butter naturally contains unsaturated fats which means it can become oxidized. Once the jar of peanut butter is opened, the fatty acids in the oil begin to lose its oxidative stability. When fatty acids in oils are exposed to oxygen, the chemical reactions that occur eventually result in the oil going rancid.

Generally, spoiled peanut butter smells and tastes terrible. If you can tell the vibe is off, don’t eat it! But if you do wind up consuming spoiled PB, there’s a chance you’ll experience stomach upset, diarrhea, or vomiting.

The high fat and low moisture of peanut butter doesn’t create an environment for most bacteria to grow. But, there have been some reported cases of peanut butter containing Salmonella bacteria. One study found that Salmonella survived in peanut butter for 24 weeks. Yikes.

Salmonella can cause serious symptoms like:

  • enteric fever (aka typhoid fever)
  • severe stomach cramps
  • vomiting
  • diarrhea

If left unchecked, salmonella can be a life-threatening concern. If you suspect you have salmonella, seek medical attention ASAP.

First things first, check your peanut butter jar’s expiration date. Most peanut butter products have these dates printed on the container or lid. If it’s already expired, don’t risk it. Now that that steps out of the way, here are some signs your peanut butter has gone bad.

  • Mold. Due to the high fatty acid-low moisture nature of peanut butter, you might not notice mold growing inside your peanut butter. However, there might be some on the inside of the lid.
  • Consistency. When fresh, peanut butter has that creamy, dreamy, spreadable consistency. But if you notice it has a hard, dry texture with a darker color to it, it’s probably time to say “thank you, next”.
  • Odor. Once the oils in the jar have been exposed to oxygen, the oil slowly oxidizes, becoming rancid. This creates a distinguished sharp, bitter, or soapy odor. Yuck.
  • Taste. Along with the pungent odor, rancid foods tend to taste horrible.

FYI: Natural peanut butter separates. If the oil is resting on top of the peanut part, that’s totally OK. However, that also means you need to use another method to see if it’s gone bad.

Here are some storage tips in order to maximize the lifespan of your favorite jar of peanut butter.

  • Seal jar securely. Be sure to put the lid back on the jar tightly. Keeping air out of the container will keep it from going rancid.
  • Mind the temperature. Keep your peanut butter in a cool, dark place (e.g. the top shelf of your pantry). You can also pop it in the fridge to make it last even longer.
  • Use a clean utensil. Avoid cross-contamination by using a clean utensil every time you scoop some out. No double dippers here!

Peanut butter can go bad. And when it does, you definitely shouldn’t eat it. Eating rancid peanut butter can lead to tummy troubles like cramps, diarrhea, or vomiting. In severe situations, it can also give you Salmonella. This can be life-threatening in extreme cases.

If stored and sealed properly, unopened natural peanut butter can last up to 12 months in the refrigerator or in the pantry. Once the container has been opened, it can last up to 3 months in the pantry or 4 months in the fridge.

The best way to determine a peanut butter’s shelf-life is to look at the jar’s expiration date. However, if you notice the peanut butter has a hard texture, darker color, or smells or tastes bad, you should get rid of it in a jiffy.


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