Why do walnuts spoil. How to prevent damage?

A walnut can go bad for many reasons:

1. Pick up too early. Collecting a walnut that is not yet fully formed and has not shown signs of maturity is unacceptable. The kernel of the walnut shrinks during drying or storage, and during processing, you can get only a “rusk”, the cost of which is low.
2. The walnut was not cleaned from the green pericarp and its residues. Washing and cleaning the walnut in the shell allows you to wash off all the coloring substances (iodine, juglone and tannins) and prevent the darkening of the walnut kernel. It is worth noting that the dark kernel of the walnut is not considered spoiled, it is suitable for consumption and use, and even many like it to taste more than the light one, but the dark kernel has a lower cost.
3. The walnut was not dried or dried incorrectly. A high-quality shelled walnut should be moderately dry, namely, have a moisture content of less than 10%. If the walnut has not gone through the drying phase, has been dried unevenly, or has not been dried to the optimum moisture content, it will become moldy. Such a walnut cannot be sold and eaten. Drying a moldy walnut, washing or heat treatment will not restore the quality of the walnut. If at least one moldy walnut is found in the bag, the entire bag, and sometimes the entire batch, is not allowed to be consumed, since the mold spreads quickly and will soon appear on other walnuts.
4. If the storage rules are not followed, the walnut can:
   - be covered with mold or rot if stored in a room with high humidity and / or without air circulation;
   - overdry and shrivel, start to release oil (rancid) if the air temperature in the room is too high.
5. Walnuts can harbor parasites - worms or other insects. This is due to improper collection, drying or storage.

To prevent damage to the walnut, you must follow the rules for collecting, cleaning, drying and storing. Nothing can be done with an already spoiled walnut, it must be disposed of. When buying an inshell walnut, it is important to check the quality by carcking. It is also important to remember that an already peeled kernel has a shorter shelf life and even more stringent storage rules compared to an inshell walnut.