Blog | Food preservation

How To Tell If Pistachios Are Bad.

A little-known fact about pistachios is that in China, the nuts are quite often referred to as the ‘happy nut’.

I’m sure you are wondering why. Well, this is because pistachios while in their shell which is slightly cracked open look like they’re smiling.

For this reason, during the Chinese New Year, pistachio nuts often have given out as gifts or favors.

These nuts are further believed to be a symbol of happiness, good health, and fortune.


Pistachios tend to grow in bunches, kind of like grapes, and are surrounded by a fleshy exterior and are actually, believe it or not, related to mangoes (crazy, I know).

When they ripen, the pistachio nut grows inside until the shell splits open revealing the nut inside.

But before we drop more interesting titbits about the happy nuts, let’s talk about a few key things relating to these green nuts.

How can you tell if pistachios are bad?

Like all other nuts, pistachios have the likelihood to go bad if they are not stored in the right manner.

There are of course a couple of ways to tell when pistachios are going bad. Foremost is to take a whiff of the pistachios.

Rotten or stale pistachios tend to give off a foul smell, sort of like paint or according to some people, nail polish remover.


A keen look at the pistachios can also give clues whether they are bad. Be wary of any mold on the pistachios.

This leads to the creation of some powdery coating on the nuts.

Also, be keen on the dried-out body of the nut that looks dehydrated, almost like it lost most of the nutmeat and there is only “excess” skin left over.

It goes without saying that the presence of any bugs or insects in the packaging, as well as an odd color of the pistachios should also be a tell-tale sign that the nuts have gone bad.

Do Pickles go bad? Click here to learn.

How Long Do Shelled Pistachios Last?


The shelf life of shelled pistachios, as with many other nuts greatly depends on the manner in which the nuts are stored.

First, for pistachios, a cool, dry area is the most ideal place for storage.

If you are keen on maximizing and extending the shelf life of your shelled pistachios after opening the packaging, it is highly advisable to place them in a tightly sealed airtight container.

These properly stored pistachios will last for about one to two weeks at normal room temperature within your pantry.


In the case where you would want to further extend the shelf life of your shelled pistachios, storing them in the refrigerator would be a great idea.

This will keep the pistachio nuts fit and fresh for about three months or so.

And yes, you can definitely choose to go a step further and freeze the pistachios.

This method will ensure the nuts maintain their best quality for about twelve months.

When freezing pistachios, it is best to do the freezing immediately you get home, and not wait a few days before getting to it.

Also, check out: How to Tell If Salmon Is Bad.

How Long Do Roasted Pistachios Last?


Roasted pistachios are available for purchase while in the shell as well as shelled ones, that is, without the shell.

I would recommend you purchase the ones in the shell for longer shelf life.

It would also be more advisable to purchase roasted pistachios in small quantities and store them in an airtight container or a heavy plastic bag.

When it comes to the roasted nuts, once stored they will last for about three to six months, that is if they are stored in the proper manner.

Alternatively, you may also choose to store your nuts in the refrigerator or freezer.

Always ensure that you have checked for the expiry or ‘sell by’ date provided on the packaging by the manufacturers.


(This is if you buy readily roasted pistachios as opposed to roasting them at home yourself).

This will give you a rough estimate of how long the dry roasted pistachios can last.

For short term storage of up to three months, it would be best to store the nuts in a pantry if you have one.

It would be more ideal to store your nuts in an airtight glass container rather than a plastic container because this will increase the length of time the nuts can remain fresh for.


It is worth noting that the key to storing roasted pistachios in the pantry is to ensure that they are not exposed to heat during storage.

This is because the heat could affect the oils in the pistachios and act as a catalyst in making the nuts go bad even quicker.

Six Months Storage

For storage of up to six months, storing your roasted pistachios in the refrigerator would be a better option.


Nuts tend to be a very smell absorbent set of foods, as such, keeping them away from other strong-smelling foods would be best (yes, even in the refrigerator).

That way you avoid them picking up the scents of nearby foods.

It is also wise to ensure that the packaging or container is airtight to prevent condensation while the nuts are in the refrigerator.

Pistachios Long-Term Storage.

For longer-term storage, freezing the nuts is the way to go.

Freezing the pistachios will keep them fresh for up to one whole year.

In order to maximize freshness, freeze the nuts immediately after bringing them home if store bought or once cooled after roasting them at home.

What do Bad Pistachios Look Like?


Generally, the consumption of stale pistachios in small quantities may not immediately lead to you becoming sick.

It would not advisable to do so as in the long run, it may lead to digestive problems or have more harmful effects on your body.

Some other more distinctive signs or pointers that pistachios have gone bad are:

  • Discoloration:
    • Fresh pistachios vary in color from yellowish red to green, if you notice that they have started to look more of brown, then they may be going bad.
  • Shriveled, dried out nutmeat:
    • This is where the outside of the nut looks dehydrated as compared to the rest of the nut.
  • Mold on the surface of the nut that creates a powdery layer on the nuts.
  • Insects or bugs in the package.
    • This is a no-brainer if you open the packaging or container and see creepy crawlies, throw the whole bag away.

What Happens If You Eat Old Pistachios?


Strictly speaking, we all know that anything under the sun has the ability to go bad, yes, even pistachios.

Now, stale pistachios are not exactly unsafe to eat (that is if consumed in small quantities) but who would want to intentionally experience that sharp unpleasant taste after doing so?

Most nuts contain some fats that react when they are exposed to heat, light, and air.

This breaks the bonds in the molecules and the fatty acids left behind are what make nuts rancid.


If you eat stale pistachios, chances are that you won’t suffer any side effects, other than the unpleasant taste in your mouth.

But in some cases, they can lead to irritation of the lining of your stomach and intestines as well which causes a stomach upset and having gas.

You may also experience nausea, vomiting, or even diarrhea.

In some very rare and isolated cases, eating such contaminated nuts may cause worse symptoms to appear right away.

If so, You ought to seek medical attention immediately if any of the symptoms you are having are severe or extreme.

Are Brown Pistachios Bad?


The pistachio fruit naturally has a hard exterior shell that is brown in color.

The seed, however, has light green flesh. When the fruit ripens, the shell changes from green to a yellowish red color.

However, according to history, when pistachio nuts were first imported to the United States from the Middle East, they were dyed in order to cover or hide the stains appearing on the shells from outdated harvesting methods being used then.

To date, some pistachios are still dyed red for marketing purposes so occasionally you may come across red pistachios.


Once you notice that the pistachios have started developing an odd dark brown color, they are going bad.

There really is no need to risk consuming the nuts at this stage.

It would be better to just throw them out and get another pack. It will save you the unpleasant sharp taste as well as a potential upset stomach and gas.

Why are My Pistachios Soft?


Your pistachios are soft because they have probably been exposed to the air and have absorbed some moisture from them.

You could try drying them up or refreshing them by toasting them in an oven. Spread the nuts out on a baking sheet or a shallow pan.

Set the baking sheet or pan in the hot oven, close the door, and turn the oven off to let the nuts cook in the preheated oven.

Five minutes should be enough for the nuts to have started browning a little. If they have, remove them from the oven and let them cool.

In case they are not dry yet, leave them inside for another three minutes or thereabout.

The pistachios can easily burn, so you have to be alert and keep a close eye on them throughout the process.

Sometimes, the pistachios will still feel a little bit rubbery and soft while hot, but the key is to let them cool off first.

After cooling they should crisp right up and have all the crunchy goodness.

Also, click here to learn; How to tell if a chicken is done Cooking.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *