Of course, walnuts last a shorter period of time if not properly stored. Opened packages will last a shorter time, again depending on the variety. But remember that nuts, unlike many other proteins, usually have an expiration date and not an expiration date. Because of this distinction, you can safely use nuts to supplement your favorite foods even after the expiration date has expired.
As a general rule, walnuts purchased in their shells will last a shorter period of time than those that have been shelled. This has a lot to do with packaging and is true as long as the package is not opened. Once the package is opened, walnuts with their shells intact will generally last a longer period of time than those that were already shelled. Most shelled walnuts retain their quality for about 4 to 6 months at room temperature.
Walnuts in shell are kept for a couple more months, about 6 to 9 months. If you choose to refrigerate your nuts, extend that period by 50 to 100 percent. Freeze walnuts if you need even more time. Yes, walnuts are very greasy, and will eventually go rancid if this is the case, they will taste very poor.
They can also dry out or, in more rare cases (especially if improperly stored) become infested with insects or molds. To keep your nuts from going stale for as long as possible, you protect them from air, heat and light. Of course, after those 12 months, you'll find stale nuts here and there, but most of the kernels will be fine. Therefore, it's a good idea not to remove walnuts from their shells until you're ready to use them.
This is especially true for walnuts, pecans, and cashews that quickly turn rancid in hot environments. Therefore, it is advantageous to know how to check if a nut is still fit for consumption or if it has passed its prime. In other words, when it comes to in-shell walnuts, open them before assuming they're in poor condition because they've been stored for too long. Place chopped or ground nuts in an airtight container or in a resealable bag that will keep moisture out.
Unlike shelled walnuts, shelled walnuts last longer because of the shell that surrounds them that gives them protection. If you store the nuts properly, you can enjoy them whenever you want without having to worry about whether your nuts have spoiled. Consuming stale or rancid nuts such as almonds, walnuts, or cashews in small amounts may not cause you to get sick immediately, but it is generally not recommended, as it can make digestion difficult or have other long-term harmful effects on the body. Refreezing frozen and thawed walnuts will greatly diminish their quality, making them soft and tasteless.
In other words, instead of relying on the printed date, you should do a quality check on your nuts and go from there. A healthy shelled nut weighs when you pick it up, and when you shake it, you can't hear the movement of the grain inside the nut. However, if you have shelled walnuts, you'll need to use some of your senses to determine if they've gone rancid. Many experts suggest that to freeze shelled walnuts, use an airtight container to make them last longer.