Have you ever pulled a walnut out of the bag and then found yourself gagging because of the bitter, rancid flavor? If so, you might be wondering whether your walnuts are bad and whether you need to throw them away.
If your walnuts taste rancid, they have gone off. They may not be unsafe to eat, but it is generally recommended that you do not consume them, as there is a chance that they could contain dangerous bacteria. They are also seriously unpleasant, so it’s best to throw them away and purchase a new bag. Bad walnuts may also have a sour smell.
We’ll look today at how you can tell when your walnuts are bad, and what to do with rancid walnuts. We’ll also cover some storage techniques that should keep your nuts as fresh as possible for as long as possible, so you don’t end up wasting them unnecessarily!
Are Rancid Walnuts Moldy?
Rancid walnuts are not generally moldy, although the two things can go together. Rancidness is a result of the fats in the nut oxidizing, and this creates changes in the fatty acids, turning them into ketones and short-chain aldehydes. These are not directly dangerous, but they taste unpleasant, and frequently smell bad too.
Unfortunately, this is an issue that walnuts are particularly known for, because they contain a large amount of fats. Although nuts do store well, walnuts that are exposed to the air will start to develop rancid oils pretty quickly, and may even go moldy if they get wet. A rancid nut is not necessarily harmful, but eating them could result in digestive issues.
It’s important to differentiate between rancid walnuts and moldy walnuts, since moldy walnuts are actively dangerous. A walnut that has got wet will often develop:
- Darker patches, or a fully dark exterior
- Patches of mold, especially where the nut has got wet
- An unpleasant, sour, or acidic smell
- A shriveled, shrunken appearance
- A mushy or soggy texture
- A strong, unpleasant flavor
You can usually eat rancid walnuts safely (although this is not recommended), but moldy nuts will need to be thrown away, as they are likely to contain bacteria that are dangerous to consume. Do not eat nuts that show any of the above signs. To be safe, you should also avoid eating rancid walnuts.
Can You Bake With Rancid Walnuts?
No, rancid walnuts cannot be used up in baking. This might seem like a good way to avoid wasting them, but unfortunately, it is likely to ruin the baking instead. Rancid walnuts have a strong, very bitter flavor, and this will come through even in baked goods. The fats will still be spoiled, so don’t put them in your cooking.
Unfortunately, there are no particularly good ways to use up rancid nuts. Once the oils have gone off, they will taste bad even when mixed with other foods. The only thing to do with them is throw them away, and store your next batch of walnuts more carefully (or use them up more quickly).
This is true for all rancid nuts, not just walnuts. Don’t put rancid pistachios, pecans, or almonds in any sort of baking; they will ruin it.
How Should You Store Walnuts?
You can store walnuts by keeping them in an airtight container, preferably in a cool, dark place. Rancidness is caused predominantly by exposure to too much oxygen, but it can also be triggered by warm temperatures and moisture. Shelled walnuts are much more prone to rancidness than unshelled ones, but either can be affected.
Some people recommend refrigerating shelled walnuts, but they can be kept at room temperature for a few weeks, provided they are sealed. If you would rather refrigerate them, it’s still important to seal them, or dampness from the fridge will get into the nuts and ruin them. Additionally, walnuts can easily absorb flavors from other foods in the fridge.
Walnuts in their shells may keep for up to 12 months, while shelled walnuts should last for up to 3 months in the fridge. If you need your walnuts to last for longer, consider freezing them. They will last for up to a year in the freezer, but should again be stored in an airtight container.
If you bite into a walnut and find that it tastes funny, check whether the rest of the container has been affected. Sometimes, it will only be one nut, but at other times, the whole batch will have turned rancid.
Conclusion
Walnuts that are rancid are not necessarily off, in that there may not be bacteria in them. However, they are not pleasant to eat, and they may cause stomach upset or discomfort. They also cannot be used in baking and will need to be thrown away. Remember to always seal your walnuts to slow down the oxidation process.
