Exposure to warm temperatures for long periods of time will cause the fat in the nuts to change and become rancid. You can tell that walnuts are getting old if they are rubbery or wrinkled. They have gone rancid if they have a strange smell similar to paint thinner. Break a piece of your nut and eat it.
The taste and flavor of the nut immediately repel you. The taste of stale nuts is an unpleasant bitter or bitter taste. If that's what your nuts taste like, spit them out immediately and discard the rest of the broth. Because the oxidation of nuts changes them at the molecular level, it's relatively easy to tell when they've gone bad.
First of all, look closely at them, have they changed color? Is there mold growing on them? Then sniff out, stale walnuts often smell a bit like alcohol and can also smell musty if they've started to get moldy. And finally, don't be afraid to try it, eating a stale nut in small quantities is not harmful, but it will taste bad and you will know immediately if they are gone. If that's the case, you'd probably like to know how long walnuts last and how to tell if a nut is in bad shape. Nuts can be stored at certain temperatures, but they generally won't last as long if stored at a warm room temperature.
The shell is an excellent protective barrier, so shelled walnuts last longer and have less stringent storage requirements. Walnuts are rounded, single-seeded stone fruits of the walnut tree that are typically used for meat after full ripening between September and November, when the shell is removed, revealing a golden, wrinkled nut shell, which is generally available in two commercial segments (three or four shells). segments). can also be formed).
While the package is closed, you can put the nuts in the fridge as is, without the need for additional wrappers. So, you can expect quality nuts to stay fresh for at least 12 months if they are still in their shell. In case you want to protect shelled walnuts from going rancid, there is no need to refrigerate them. The University of California guidelines are a little more relaxed and state that shelled walnuts last four months, while shelled walnuts last three months in the pantry.
When properly stored in the pantry, walnuts can last up to 4 weeks, this can be extended to 12 months in the fridge and up to 24 months in the freezer. As I mentioned in the spoilage section, walnuts are prone to going rancid, thanks to their nutritional profile. There's a reason stale nuts are called “rotten,” and that's because, for some unknown reason, they turn green when left on a counter, in a closet, in direct sunlight, or in the trunk of a car. The best preventive measures are the nut shell itself, a sealed container, darkness and stable cold temperatures.
Of course, after those 12 months, you'll find stale nuts here and there, but most of the kernels will be fine. For shelled walnuts, refrigeration is what I recommend, especially if you need them to last longer than a couple of months. While it's true that walnuts stay fresh and edible for a long time, there comes a point where they don't taste good anymore.