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Can Pistachios Go Bad?

Found an old package of pistachios stored away in a cabinet? That’s not unusual. You probably put it there with the best intentions, but after storing there a bunch of other products, you forgot about it altogether.

Now that this package is in your hands, you want to know if pistachios can go bad. And how to tell if they are okay to eat or not.

This article covers exactly that, plus other useful information about those nuts, such as their shelf life, and the best way to store them.

Sounds interesting? Read on.

Bunch of shelled pistachios
(credit: Joanna Kosinska)

Can Pistachios Go Bad? How Do You Know If Pistachios Are Bad?

Technically speaking, every food product can go bad, even honey if you help it. Nuts definitely go bad, and there are a couple of things to look out for:

  • signs of mold on the nutmeat
  • dried out body of the nut that looks like it lost most of the nutmeat and there’s mostly “leftover” skin
  • bugs or insects in the package (if that’s the case, discard the whole thing)
  • odd color (pistachio nutmeat should be yellow to green)

More often than not, the nuts look alright, even if you stored them for quite a long time. If that’s the case, the next step is to check if they are rancid. Two main signs of rancidity are:

  • harsh, paint-like smell
  • sharp, unpleasant taste

Rancid pistachios aren’t unsafe to eat (UOCN), but the experience isn’t a pleasant one. If your pistachios are rancid, throw them out.

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

If the nuts aren’t rancid but do taste a bit stale, try shelling and toasting them on a stick-free skillet for a couple of minutes until they get fragrant.

That brings us to the next topic: shelf life.

How Long Do Pistachio Nuts Last?

If you’ve ever read that pistachios last only a couple of weeks at room temperature, you’re not alone. Such info can be found on the University of California’s site (UCANR).

If you do a bit of digging, you can find that the USDA doesn’t particularly agree with that by stating (USDA):

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? Well, 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 temp. And I think this estimate is closer to the truth than the super short ones you can find online.

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

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

Of course, if you wish to store pistachios for a prolonged period, like a year or longer, cold storage is the way to go.

Long story short, pistachios should retain quality for half a year at room temp, about a year in the fridge, and close to two years in the freezer. I’m not sure who buys so many nuts that they need them to keep up for two years, though.

If you’re buying pistachios packaged, check the label. Remember that the date there is just an estimate, and it’s okay to eat out of date pistachios. Make sure that they aren’t bad or rancid, of course.

Last but not least, unshelled pistachios last a bit longer than shelled ones. That’s the case for many other nuts (e.g., hazelnuts and walnuts) that you can buy in both varieties.

Heap of pistachios
Heap of pistachios

How To Store Pistachio Nuts?

We’ve already briefly touched upon this. You already know that room temperature or slightly lower is okay for short- to medium-term storage. And if you need the nuts to last for longer than half a year, a fridge or a freezer is in order (UOCN).

Now let’s talk about specifics, such as packaging.

If you buy pistachios from the bulk bins in a supermarket (make sure they’re fresh!), you probably get home with a plastic or paper bag with the nuts. That’s good enough for short term storage, like a couple of weeks, but that’s it. If you want to keep the nuts for as long as possible, pour them into a resealable container or bag. Such a container is a must when storing in the fridge, so the nuts don’t pick up any smells.

If you prefer packaged pistachios, they often come in resealable bags, so that’ done for you. If that’s not the case, transfer the nuts into one after first opening the packaging.

When leaving pistachios at room temperature, make sure they sit away from any sources of light and heat. A cabinet in the kitchen or pantry usually does that job pretty well.

Protecting the nuts from air, light, and heat prevents them from going rancid (WIKI).

Pistachios in a glass bowl
Pistachios in a glass bowl

In a Nutshell

  • pistachios can go bad, but if you take good care of them, that won’t happen for a long time
  • choose fridge or freezer for long-term storage, pantry for short- to medium-term
  • keep the nuts in an airtight container
  • if storing at room temperature, remember to put them away from heat and light