1. The dark brown skin of walnut kernels may not be edible.

2. There are many reasons that can cause the skin of walnut kernels to turn black. For example, when the skin of walnut kernels comes into contact with air, oxidation will occur. At this time, the skin of walnut kernels will turn black. In this case, we can continue to eat this walnut.

3. But sometimes the black skin of walnut kernels is also because the walnuts have been stored for too long. During this process, the walnuts will gradually deteriorate and become rancid, which will also cause the black skin of the walnut kernels. In this case, In this case, you cannot continue to eat walnuts.