Do Walnuts Become Toxic After Long Storage?

I have walnuts that I picked myself, some of the shells are still green. Do I have to remove them and how long can I store my walnuts? Do you have tips for proper storage?

Walnuts can be stored in the shell in an airy, cool and dark place for around 12 months. You should take a closer look at older nuts before you eat them. If you catch a nut that tastes bad, it’s better to spit it out.

The nut kernels can also be frozen. The sooner that happens, the better.

Nuts can become either moldy or rancid.

If the nuts are rancid, the fat they contain has gone bad. Under the influence of light, oxygen and moisture, the fats are broken down and products are created that not only smell and taste bad, but are also sometimes harmful to health. Our sensitive sense of smell and taste usually protects us from consuming rancid nuts in large quantities. If this happens anyway, gastrointestinal upsets can be the result.

Mold often appears on nut kernels and shells as a whitish-grey coating. It can be furry-fluffy with tiny hairs, or it can appear like a fine spider web.

As a precaution, nuts that show traces of mold should not be eaten, even if this is only visible on the shell. Nut mold can contain toxic mycotoxins.

Proper storage of self-harvested walnuts

When it comes to walnuts, the time of harvest is very important. Only when they are really ripe can they be stored after drying.

You can tell when the walnut is ripe when the green shell of the walnut bursts open. Most of the time, they soon fall to the ground. During harvest time, it is therefore important to pick up the nuts from the ground every day. Otherwise, the moisture would encourage mold growth.

You can simply “peel off” the green coat of ripe nuts with your hands. Any residue can be brushed off with a brush. Gloves should be worn if possible, since the tannic acids contained darken the skin quite stubbornly. Under no circumstances should you wash the nuts, as the moisture causes the nuts to mold more quickly.

After that, the walnuts should dry spread out for about two weeks. Turn several times a day. The nuts should not be on top of each other or touching. Sorting out stained or shriveled nuts is important.

It is best to keep the nuts in airy packaging in sacks or nets in a frost-free, but as cool, dark and dry place as possible.
Ideally, the nuts will last until the next harvest season.