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Do Pistachios Go Bad? Pistachios Shelf Life and Spoilage

Today we’re going to cover the shelf life, storage, and spoilage of pistachios.

Say you’ve just found a bag of pistachios stored away in a cabinet in the kitchen. Unfortunately, it’s a couple of months past the “expiration” date, and you’re wondering: do pistachios go bad?

That’s when knowing how long pistachios last or how to tell when pistachios are bad is helpful. And that’s what we’re going to cover below.

Let’s jump right in.

A bag of pistachios

Table of Contents

Do Pistachios Go Bad?

Pistachios go bad when stored for too long or in warm or humid conditions.

Like other nuts and high-fat products, pistachios sooner or later go rancid. You’ll know that you have rancid pistachios when they start to taste bitter and sharp. They might also begin to give off a crayon- or paint-like smell, but that’s not always the case.

Rancid pistachios aren’t necessarily unsafe to eat, but the experience isn’t pleasant. If your pistachios are rancid, throw them out.

(In other words: you can eat them if you like, but I wouldn’t risk baking a pistachios cake with these.)

Now, going rancid isn’t the only possible sign of spoilage. Let’s talk about others.

Bunch of shelled pistachios
(credit: Joanna Kosinska)

How to Tell if Pistachios Are Bad?

Toss your pistachios if:

  • There are pantry bugs in the bag. If your pistachios sit in the pantry or kitchen cupboard and you have some insect issues, those little guys can get to your pistachios too. Assuming that the nuts don’t sit in a sealed bag or container, of course. If you find eggs, dead insects, or anything of the like in the nuts, toss them.
  • There’s mold. While mold growth on pistachios isn’t likely to happen, those nuts are done for if you notice any.
  • They are rancid. To examine pistachios, check their smell and taste. If they smell like old paint or putty, they are rancid nuts. Same thing if the flavor is sharp, biting, and bitter.

Again, what’s most likely to happen to your old pistachios is that they will go rancid.

The good news here is that pistachios don’t go rancid that easily thanks to a relatively low amount of polyunsaturated fats.

But what if those pistachios aren’t rancid or spoiled but simply taste meh?

Using Stale Pistachios

If your pistachios have lost their freshness and taste stale, not all is lost. Here’s what you can do with stale pistachios:

  • Toast them on a non-stick skillet for a couple of minutes until they get fragrant. They won’t taste as good as fresh pistachios but should taste better after that treatment. Alternatively, you can toast them in the oven.
  • Stir them into ice cream or any other dessert.
  • Use them in a baking project. If you’re into baking, you can try a new pistachio recipe or simply fold them into muffins, cupcakes, or yeast breads that you bake regularly.

Next, let’s briefly cover unopened pistachios.

Unopened Pistachios

Not all pistachios open up. If you’re buying unshelled pistachios, sooner or later, you’ll find a few (or a lot) nuts that only have a tiny crack or are completely sealed. That’s normal.

Those not-quite-open pistachios are still okay to eat. Some popular opening strategies include:

  • Using a nutcracker. Just be gentle; these are not walnuts.
  • Opening using a knife. If there’s a small crack, insert a knife into it to split the pistachios open.
  • Using a rolling pin. Wrap the nuts with a kitchen towel and roll over them gently until you hear the shells cracking.

Obviously, any other strategy you use when shelling other nuts should work too.

Pistachio nuts

How Long Do Pistachios Last?

Pistachios keep quality for about 6 months at room temperature in the pantry or kitchen or about 12 months in the fridge. Unshelled pistachios last slightly longer than shelled ones.

If you need your pistachios to last for even longer, freeze them.

(More on freezing later on.)

Now, you might’ve read that pistachios last only a couple of weeks at room temperature. For instance, you can find such info on the University of California’s site.

But if you do some digging, you can find that the USDA doesn’t particularly agree with that by stating:

Once they have been dried, nuts can be held at 20 ºC (68 ºF) and 65 to 70% RH for up to a year (Ferguson et al. 1995).

Who should you trust? Many pistachio retailers say on the labels that if you keep the nuts appropriately stored, they can last for half a year or even longer at room temperature. And I think this estimate is closer to the truth than the super short one.

It makes even more sense if you remember that pistachios don’t go rancid quickly, which I mentioned earlier.

All in all, those shelf life suggestions are about how long the nuts retain the best quality, not how long it takes for them to go bad. And because of that, all of those suggestions have some merit to them, in a sense.

Long story short, instead of relying on dates, check the quality of your pistachios to determine if they’re still okay to use or not. And if you know from the get-go that yours will sit in storage for a prolonged period, like more than six months, refrigerate them.

Unshelled pistachios in a wooden bowl
Unshelled pistachios in a wooden bowl

Shelled vs. In-Shell Pistachios

Unshelled pistachios retain good quality for a couple of weeks, maybe a month or two, longer than shelled ones. That’s because the shell protects the nutmeat from some of the air and humidity.

Of course, since most pistachios are split open, that protection is limited. That’s why the shell gets you some extra weeks and does not double the overall storage time.

For nuts such as hazelnuts and walnuts, the shelf life difference between shelled and unshelled ones can be pretty significant. Unfortunately, that’s not the case for pistachios.

(Check out my articles: Do hazelnuts go bad? and Do walnuts go bad? for more info.)

Last but not least, take convenience into account. If you’re much more likely to eat those pistachios if you buy them shelled, sacrificing a couple of weeks of shelf life is probably worth it.

Next, let’s talk about the date printed on the label.

Expiration Date

If you’re buying pistachios packaged, there’s probably a best-by date on the label somewhere. Remember that this date is just a rough estimate and not an expiration date by any means.

In other words, pistachio nuts typically keep way past that date, and eating out-of-date pistachios is okay.

Before digging in, check the nuts for signs of spoilage I outlined in the spoilage section. And if everything is fine, enjoy them, no matter the date.

(Of course, if your pistachios are six months past their date, and that’s enough to make you uncomfortable eating them, feel free to toss them.)

If you’re buying pistachios in bulk, there’s no date on the label. That makes things even more straightforward: you can only rely on the quality of the nut.

Pistachios best-by date
Pistachios best-by date

How To Store Pistachios?

Store your pistachios in a container or bag in the fridge if you need them to retain quality for about a year. If around six months of storage time is enough for you, an airtight container or resealable bag in a cupboard is okay.

As you probably know, you need to store nuts in the fridge or freezer if you want them to last a long time. However, if a slightly shorter storage time is okay, you can leave them at room temperature.

To keep your nuts from going rancid too soon, you need to protect them from air, light, and heat. Let’s talk about specifics.

In the Fridge

When storing pistachios in the fridge, make sure the nuts are sealed tight in a freezer bag or storage container. This way, they don’t pick up any odors from nearby foods and don’t absorb any moisture.

If you have a small fridge and can’t spare any space, or simply don’t need your pistachio nuts to last months on end, you can leave them at room temperature. Here’s how.

Heap of pistachios
Heap of pistachios

Room Temperature Storage

Transfer your pistachios into an airtight container or freezer bag, and place it in a cool and dark place, such as a cupboard in the pantry. Make sure the nuts sit away from sunlight and heat sources, such as the oven and heaters.

That’s the best way to store them at room temperature.

Alternatively, if you need to store pistachios for a short period (think a few months tops), using a ventilated bag is okay too.

Those bags allow plenty of airflow, which is far from ideal, but at least ensure any humidity easily evaporates. Because of that, they are okay as a short-term storage option.

If you have a problem with pantry bugs, use a freezer bag or, better yet, an airtight container. A ventilated bag is an easy target for any insect out there.

Pistachios in a glass bowl
Pistachios in a glass bowl

Can You Freeze Pistachios?

Pistachios freeze perfectly fine, and if you want to store yours for more than a year, it’s best to freeze them.

Here’s how you freeze pistachios:

  1. Place the pistachios in a freezer bag.
  2. Squeeze out the air.
  3. Seal the bag.
  4. Freeze it.

A minute or so of active time, and you’re done.

(The same method works for freezing other nuts, including pine nuts and Brazil nuts.)

Pistachios don’t stick tight when frozen, so you don’t have to bother with any pre-freezing to be able to grab a bunch without defrosting them all.

To use frozen pistachios, scoop them from the bag and let them sit on the counter for 30 minutes to warm up a bit. Then they’re ready for snacking.

If you need them for baking purposes, you can probably skip defrosting.

Pistachios Shelf Life and Spoilage Summary

Thank you for reading. I hope you found this guide helpful. Here are the key takeaways:

  • Pistachios eventually go bad. If you store them long enough, the most common scenario is that they’ll go rancid.
  • You can tell your pistachios are rancid if they’ve turned bitter and sharp or smell like old paint. Flavor change is much more common than smell change.
  • Bagged pistachios come with a date, but that date is only a rough estimate of how long pistachios last. Pistachios, similar to other nuts, often retain good quality way past that date. Check the nut’s quality instead of relying on dates.
  • You can store pistachios in a cupboard at room temperature for at least half a year or refrigerate them for at least a year. In-shell pistachios typically retain quality slightly longer than shelled ones.