Walnuts contain oil and because of that they can easily turn rancid. Light, moisture and heat will all reduce the shelf life of your walnuts by causing the oils to change structure. Walnuts should smell mildly nutty and have a sweet taste. If they smell bad, they are probably rancid and you should throw them away.
To ensure the best taste, wait to shell or chop walnuts until you’re ready to use them.
Walnuts thaw quickly at room temperature and can actually be used straight out of the refrigerator or freezer.
Occassionally we hear of cases where walnuts have been contaminated with bacteria (such as E. Coli). If you suspect this is the case for walnuts you have stored, throw them away. In both the US and Canada, there are government websites that lists all recent food recalls. Make sure that you are not eating anything on these lists.
Walnuts with Shells Removed:
Walnuts that have had their shells removed need to be refrigerated or frozen.
When storing walnuts in the refrigerator, you need to keep them in an air-tight container away from other foods. Walnuts easily absorb moisture and odors from other foods, and food with strong odors (fish, onions) can seriously affect the taste of walnuts.
They can be stored in the refrigerator for up to 6 months.
Walnuts can be stored in the freezer for up to 1 year.
Walnuts in the Shell:
Walnuts in the shell should be stored in a plastic bag in a cool dry place. Do not store them in the vegetable crisper of your refrigerator because the humidity will cause them to deteriorate much faster.
Walnuts in the shell can be stored for up to 3 months.
Walnut oil should be stored in a cool, dark place for up to 3 months. To prevent walnut oil from becoming rancid, refrigeration is best.