Why Do Walnuts Go Stale So Quick And How To Store Them

If you’ve ever bitten into a rancid nut, then you’ll know that it’s not a pleasant experience and often means that the whole batch has sadly become stale and will need to be thrown out. Walnuts, in particular, have gotten themselves a bit of a bad reputation as a nut that goes bad very quickly, and this is due to their nutritional composition. So why do walnuts go stale more quickly than other nuts? And how can you store them to make them last longer? Read on to find out more. But if you've only started eating walnuts recently you might find our article on Everything You Need To Know About Walnuts a little more useful.

Why do walnuts go rancid so quickly?

To understand why walnuts go rancid so quickly, we first need to know a little more about the process of rancidification itself. Rancidification happens when fats and oils are exposed to air, light, moisture or bacteria, causing them to oxidize and to change at a molecular level. When oxidation occurs, fatty acids and oils, like those found in nuts, begin to change into short-chain aldehydes and ketones, which taste unpleasant and smell bad.  

The reason why walnuts go rancid so quickly is that they contain a very high level of fatty acids, meaning that they are more susceptible to oxidation when stored incorrectly. Other nuts that go rancid very quickly include pistachios and pine nuts, which also have a very high-fat content. The good news is that the oxidation process can be slowed down by storing nuts correctly. 

Before worrying about storing walnuts make sure you are buying fresh, good quality walnuts so your chances of a rancid walnut are slim to none! Check out our blog post on How To Make Sure Your Getting Fresh Quality Walnuts

How to store walnuts to stop them going rancid

The key to stopping walnuts from going rancid is to protect them from the key factors that cause oxidation, which include moisture, light, air and bacteria. Walnut shells naturally protect walnuts from some of these factors, increasing their shelf life, but shelled walnuts have no natural defense. 

To improve the shelf life of your walnuts, always store them in a clean airtight container, this will prevent moisture and air from getting to them and will also stop unwanted odours from tarnishing their flavour. To protect them from sunlight, store them in a dark place or in a dark-tinted container.  Another common enemy of walnuts is temperature, and so to extend the shelf life of your nuts even further, you may also want to consider storing them in the fridge or even the freezer. When stored correctly in the pantry walnuts can last for up to 4 weeks, this can be extended to 12 months in the fridge and up to 24 months in the freezer. 

How to tell if your walnuts have gone rancid?

Because the oxidation of nuts changes them at a molecular level, it is relatively easy to tell when they have gone bad. Firstly, look at them closely, have they changed in colour? Is there any mould growing on them? Then give them a sniff, rancid nuts often smell somewhat alcoholic and can also smell musty if they have begun to go mouldy. And finally, don’t be afraid to give one a taste, eating a rancid nut in small quantities is not harmful, but they will taste foul and you’ll know immediately if they have gone off. 

If you’ve ever bitten into a rancid nut, then you’ll know that it’s not a pleasant experience and often means that the whole batch has sadly become stale and will need to be thrown out. Walnuts, in particular, have gotten themselves a bit of a bad reputation as a nut that goes bad very quickly, and this is due to their nutritional composition. So why do walnuts go stale more quickly than other nuts? And how can you store them to make them last longer? Read on to find out more. 

Why do walnuts go rancid so quickly?

To understand why walnuts go rancid so quickly, we first need to know a little more about the process of rancidification itself. Rancidification happens when fats and oils are exposed to air, light, moisture or bacteria, causing them to oxidize and to change at a molecular level. When oxidation occurs, fatty acids and oils, like those found in nuts, begin to change into short-chain aldehydes and ketones, which taste unpleasant and smell bad.  

The reason why walnuts go rancid so quickly is that they contain a very high level of fatty acids, meaning that they are more susceptible to oxidation when stored incorrectly. Other nuts that go rancid very quickly include pistachios and pine nuts, which also have a very high-fat content. The good news is that the oxidation process can be slowed down by storing nuts correctly.  

Got walnuts that you need to use up? Check out 3 Quick Recipes With Walnuts