October 31

How Long Does Peanut Butter Actually Last?

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You’re faced with the common pantry dilemma. You're staring down the tube of a questionable container of peanut butter and you have to know...

is it safe?

I have no way of telling you with 100% confidence your peanut butter is still good, but I can help you get there.  

This article answers the frequent kitchen question of, "How long does peanut butter last?"

Enjoy!

A Few Important Notes


First, if you're truly concerned about the quality of the peanut butter, just throw it out. Better to be safe than sorry. Plus, you can rest easy with a fresh container from the grocery store.  

But to ease your nerves, here's a few more things to consider:

Secondly, Peanut butter has a very low moisture content, thus it is not a suitable environment for most "bad" bacteria. That doesn't mean pathogenic infection isn’t possible, it means that it's highly unlikely (some rare cases 1, 2, 3). So unless you leave your peanut butter container open in the bathroom or next to your raw chicken supply, it's probably harmless.  

Thirdly, peanut butter is full of unsaturated fats. These fats can become oxidized by oxygen in the environment which can lead to some rancid, unpleasant odors. This usually takes a pretty long time to happen, but the process is sped up if the peanut butter is left opened for extended periods of time. These molecules are harmless to your body, just unpleasant to taste.   

If you're still concerned, let's do a peanut butter quality test to find out if your peanut butter is still O.K. to eat.

Peanut Butter Quality Test


Step 1) Take your peanut butter container and look for any holes or deformities. Also take a look at the cap for any obvious breaks in the seal. 

- Any holes or deformities can lead to excessive oxidation and therefore rancid smells. Holes can also increase chance of inoculation by harmful bacteria. If you find any openings, best to throw it away. 

peanut-butter-and-peanuts


Step 2) If the container is well intact, check for an expiration date to get an idea of how old it is. 

- If you are still within the expiration range, your peanut butter is probably fine and ready to eat. If not, continue on.


Step 3) If the container is well intact, open the lid and look for any discoloration in the peanut butter. Look through the side of the container as well. 

- Any discoloration could be a result of bacteria and/or mold. If this is the case, best to throw it away.


Step 4) If the color is consistent with peanut butter, time to use your nose. Take a quick whiff from a distance. If it doesn't repulse you, draw your nose closer. 

- If the peanut butter smells bad, it will definitely taste worse. This means your peanut butter has gone rancid. Best bite the bullet and go to the store for a fresh container. 


Step 5) Alright, if it passed the smell test, it's time to dig in! Put a small portion on a spoon and place it on your tongue. This is the ultimate quality test and will reveal whether the peanut butter is worth eating or not. 

- If you're satisfied with the flavor, then the peanut butter is most likely fine. If you’re still concerned and want a window of time to refer to, check the table below.


Peanut Butter Shelf Life References

Reference

Container

Temp

Time Window

-Opened 

-Unopened

Room Temp

3 Months

6-9 Months

-Opened 

-Unopened

Room Temp

2 Months

6 Months

Reference: University of Nebraska, Lincoln
Opened Container @ Room Temp: 2 Months
Unopened Container @ Room Temp: 6 Months

Reference: Spruce Eats
Opened Container @ Room Temp: 3 Months
Unopened Container @ Room Temp: 6-9 Months

So...what is the right answer? 

It's hard to give a universal answer for all circumstances. Surely there are those rare instances where the peanut butter looks and smells good, but has gone bad. 

And vise versa.

Lets say you have a tube of peanut butter that has had relatively low exposure to oxygen (no holes and kept closed more often than not). It's probably perfectly fine for the durations mentioned above, or even longer for that matter.

Just be mindful that some pathogenic bacteria can survive in peanut butter, they just can't proliferate. So keep the cap on and keep it away from your raw meat. 

Other Frequently Asked Peanut Butter Questions


-Does peanut butter go bad?

Peanut butter shelf life survival will completely depend on your definition of "gone bad."

If bad = accumulates unappealing flavors over time, then yes, peanut butter can go bad over time. Like most things in life, oxygen does not help flavor. It tends to create unappealing qualities in everything we attempt to preserve. 

If bad = fosters pathogenic bacteria that can directly effect health, probably not. But in rare cases, the wrong bacteria can get inside and survive. Salmonella is the main offender (1, 2). If inoculated in the peanut butter, the fats have an odd way of protecting the bacteria. They won't thrive, but they may survive.  

It should be noted, these infections are highly unlikely to breed in the home. However, it can happen at the factory, and on a massive scale. Make sure to choose a brand that you trust.

Here is the FDA's guidelines for what criteria peanut butter must meet to be considered peanut butter. 

-Does Peanut Butter Last Longer in the Fridge?

Yes, peanut butter will last longer in the fridge. The fridge slows down oxidation and any enzymatic breakdown that may be occurring. The question becomes, what flavor & texture sacrifices are you making when you store peanut butter in the fridge?  

With many of the "unnatural,” partially hydrogenated peanut butters, refrigeration will result in a tougher consistency. This may make it slightly harder to spread. This usually only becomes a problem when using softer, more delicate bread.

With "natural" peanut butter, there are usually no secondary oils added (no partially hydrogenated oils). Without the partially hydrogenated oils, the oil and peanuts can separate and make for an even tougher consistency when refrigerated. .  

Neither of these scenarios occur if you stir the peanut butter frequently.


-Can You Freeze Your Peanut Butter?

You sure can. 

If you decide to do this, oil separation may become more drastic. There aren't many instances where this would be a good idea. If you were trying to keep the peanut butter stable for as long as possible, this would be the way to do it.

-How to Properly Store Your Peanut Butter

Always follow the guidelines on the container. I like preserving my peanut butter in the fridge for flavor stability and the coolness of the taste. If unopened, I leave it in the cupboard. If opened, I always put it in the fridge. I eat peanut butter on a daily basis though, so oil separation is never an issue. 

-Will a Peanut Butter Sandwich Go Bad?

peanut-butter-and-jelly-sanwich

Let's break down all the ingredients of a true PB&J:

Peanut butter = Long shelf life

Jelly = Long shelf life

Bread = Usually very short shelf life 

The bread will notoriously be the first to go bad on a peanut butter and jelly sandwich. If you see any noticeable mold, steer clear. But If you made a PB&J and left it in the fridge for a day or so, it should be fine as long as the bread is still good.  

-Does Oil Separation Mean the Peanut Butter's Gone Bad?

Oil separation after storage just means the oil (non-polar segment) detached from its peanut (polar segments). This is actually how peanut butter would naturally be, if it had not been forced into mixture.

Companies add partially hydrogenated oils to make the peanuts and oil more miscible, but it doesn't completely alleviate the problem. This happens more often with longer storage, especially in the fridge. Nothing to worry about, unless the flavor becomes unappealing. 

-How can I Store Peanut Butter to Increase Shelf life?

Again, my best advice is to store it in the cupboard until you break the seal. Then, leave it in the fridge. The accepted recommendations are 6-9 months in the fridge, but that's just an estimate. Kept in the fridge, peanut butter can usually last for a long, long time.

-Does Peanut Butter Expire?

According to the expiration date on the peanut butter, yes, peanut butter expires. As far as physically making you sick, it is highly unlikely. 

-How Long Can You Eat Peanut Butter After it Expires?

You can wait for a long time after the expiration date as long as the container is fully intact. But again, the flavor will change with oxidation, so its up to your standards of what constitutes quality peanut butter.  

-Can Expired Peanut Butter Harm You?

If the expired peanut butter is inoculated with pathogenic bacteria, yes. Again, this is rare, but in the right circumstances, some bacteria can survive in a low water activity environment. 

-Can You Do Anything with Old Peanut Butter?

If you find the peanut butter hanging out in the cupboard for too long, finding creative ways to use it can be fun. That is, if the peanut butter quality is still good and no rancid smells are detected.

Try using the peanut butter in a dessert.

Having that peanut butter undertone can really provide some great flavors in desserts like cookies, pastries and cakes.   

Peanut-butter-cookies

Concluding


I hope this article was helpful. Peanut butter has been my go-to food for life, and knowing how long it's going to last is just a part of loving it. If you have any questions or comments, please don't hesitate to leave a comment below. I'd love to hear if you feel differently about the true shelf life of peanut butter.

Thanks for listening,

Michael

Founder of Robust Kitchen


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About the author

Michael spends his days eating, drinking and studying the fascinating world of food. He received his Bachelors Degree in Food Science and Technology at the University of California, Davis and spent much of his time at the school brewery. While school proved to be an invaluable experience, his true passion lies in exposing the hidden crannies of food for the cooking laymen.

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