Tasting
Storing pistachios: in the shell, shelled, as a cream
A pistachio doesn’t really go off: it goes rancid. Cold, darkness and a well-sealed jar put that moment off by several months. Here is how long they keep, form by form.
We tend to think nuts last for ever. Pistachios last less well than most: they are a fatty nut, and fat ages badly. Stored properly, they keep for a year. Forgotten in an open bag above the oven, they are spoilt within a few weeks.
How long do pistachios last?
It all depends on temperature. The most precise figures come from the Postharvest Technology Center at the University of California, Davis, and apply to raw pistachios.
| Temperature | Shelled | In the shell |
|---|---|---|
| 0 °C | 10 months | 12 months |
| 10 °C (cool cellar, bottom of the fridge) | 3 months | about 4 months |
| 20 °C (kitchen cupboard) | 1 month | about 6 weeks |
| 30 °C (kitchen in summer) | 1 week | best avoided |
| Freezer | a year or more | |
Two points to bear in mind when reading this table. The in-shell figures at 10 and 20 °C are estimates: the source only says that the shell extends storage life by 25 to 50%. And these are periods of best quality, not cut-off dates: after that, the pistachios are not dangerous, they simply start to lose their flavour.
Where should you keep pistachios?
Four rules, in order of importance.
- Somewhere cool. Ideally between 0 and 10 °C, and never above 20 °C. The fridge is therefore the best place, especially in summer and for shelled pistachios.
- Away from air. A glass jar with a rubber seal, or an airtight tin. Producers pack under vacuum or under nitrogen for the same reason: oxygen is what turns them rancid.
- Away from strong smells. Pistachios pick up the smells of whatever is next to them. A sealed jar solves that too.
- Dry and dark. Damp makes them soft, and light speeds up oxidation.
In practice: an open bag you will finish within the month can stay in the cupboard, in a jar. Beyond that, put it in the fridge.
Can you freeze pistachios?
Yes, and it is the best way to keep a stock. Frozen, pistachios keep for a year or more without losing their flavour. Put them in a well-sealed freezer bag, pressing out the air. To use them, let them come back to room temperature in the closed bag, so that condensation forms on the bag and not on the nuts.
Why do some pistachios keep less well than others?
Because every bit of processing exposes a little more of the fat to the air.
| Form | Storage life, compared with the whole raw kernel |
|---|---|
| In the shell | 25 to 50% longer |
| Shelled, raw, whole | the reference |
| Chopped, in pieces or ground | half as long |
| Roasted | up to four times shorter |
The shell is the best packaging there is: it protects the kernel from air and light. That is why we advise buying in the shell whatever you want to keep, and only chopping or roasting pistachios when you are about to use them.
How can you tell if pistachios are rancid?
- The smell. A fresh pistachio smells of very little. A rancid one smells of paint, putty or old cardboard.
- The taste. Acrid and bitter, with a feeling that lingers at the back of the throat.
- The colour. The kernel turns brown and loses its green.
A pistachio that has simply gone soft, with no bad smell, has taken on moisture: a few minutes in a low oven will make it crunchy again. On the other hand, the slightest trace of mould is a reason to throw away the whole batch. Moulds on nuts can produce aflatoxins, toxins that EU regulations limit to 10 micrograms per kilo in pistachios sold to consumers.
Can you eat pistachios after the date on the bag?
Usually, yes. The date printed on a bag of pistachios is a “best before” date. It is about quality, not safety. Once it has passed, smell and taste them: if the pistachios are neither rancid nor mouldy, they are fine.
How do you store pistachio cream or paste?
It depends entirely on what is in it.
- A 100% pistachio paste contains almost no water, which makes it very stable. The technical data sheet of one French manufacturer gives a shelf life of nearly three years between 3 and 15 °C, and states that it does not need to be refrigerated, even once opened. Over time the oil rises to the top: that is normal, just stir it back in.
- A sweetened paste or cream containing water, syrup or milk is a different product. A pastry paste with 48% pistachio has to be kept in the fridge, and only for one month after opening.
If in doubt, read the label: if water or milk is on the ingredients list, it goes in the fridge. Always use a clean, dry spoon.
Frequently asked questions
Should pistachios be kept in the fridge?
There is no need for a bag you will finish within the month. It is a good idea beyond that, in summer, and for shelled pistachios: between 0 and 10 °C, they keep three to ten times longer than at room temperature.
Do pistachios go off?
They don’t become dangerous with age, unless they go mouldy. They go rancid: their fat oxidises and takes on an acrid taste. Kept cool and away from air, that moment can be put off by several months.
How long do shelled pistachios last?
About a month at 20 °C, three months at 10 °C and ten months at 0 °C for whole raw pistachios. Half that if they are chopped.
How do you store fresh pistachios?
Fresh, undried pistachios are perishable: keep them in the fridge and eat them quickly. We have not found a published reference figure for how long they last. Shop-bought pistachios, on the other hand, are dried to below 7% moisture, which is what allows them to keep.
How do you make soft pistachios crunchy again?
Spread them on a baking tray, give them a few minutes in a low oven, then let them cool in the open air. This won’t rescue pistachios that have gone rancid.
Sources
- Pistachio: postharvest fact sheet, UC Davis Postharvest Research and Extension Center, 2025.
- Storage temperatures and storage life for nuts, M. Cantwell, UC Davis Postharvest.
- 100% pistachio purée: technical data sheet, Jean Hervé, in French.
- Regulation (EU) 2023/915: maximum levels for contaminants in food, EUR-Lex, French-language version.
- Raw pistachios: nutrient composition, USDA FoodData Central.
