Immediately after picking the walnut, its kernel has a light milky kernel color. In some cases, it can be dark, but this is more of an exception, as walnut diseases occur during ripening or this is a feature of the variety.
Over time, the kernel darkens, acquiring a permanent color. This happens during the drying of the walnut and is a completely normal process. The kernel may become slightly darker, but still remain light, becoming wheat, amber or dark amber in color.
What does the color of the walnut kernel depend on and why does it darken?
The color of the walnut kernel depends on:
- kind of walnut;
- the presence of diseases or pests during the ripening process;
- timeliness of collection;
- the timeliness of peeling the walnut from the green skin;
- drying conditions.
If the type of walnut assumes a dark color, nothing can be done about it. If damage in the form of spots or pests appeared on green walnuts during formation and ripening, this problem needs to be solved immediately.
As for the conditions for collecting, peeling and drying walnuts, it is necessary to adhere to the rules that were compiled by the world's walnut producers. Based on experience, observations and experiments.
- The walnut should be harvested immediately after its ripening - when the green skin has started to crack.
- A walnut that has fallen to the ground must be collected immediately.
- In wet weather, the walnut must be collected as quickly as possible, since the walnut absorbs this moisture along with the coloring substances.
- After harvesting, the walnut is immediately cleaned from the green skin, as it contains coloring substances - iodine, juglone and tannins. They are the ones that most affect the color of the kernel, making it darker.
- Do not allow the green skin to darken on the walnut.
- After collecting and peeling the green skin, the walnut is sent to dry naturally or in industrial dryers. Both methods of drying walnuts must comply with the following rules:
- the optimal drying temperature must be selected so that the kernel does not dry out;
- there must be good air circulation;
- it is advisable to stir the walnut from time to time so that drying occurs evenly.
If you follow these rules, you will get a walnut with the lightest kernel.