There is something wrong with the quality of chestnuts or chestnuts have been boiled for too long and have not been soaked in water.

Chestnut blackens, except that the growth environment is similar to the lack of light, which leads to the fruit blackening, mainly because it is stored for too long. Old chestnuts range from one year to three or five years, and are frozen and preserved. Compared with good chestnuts, the pulp of aged chestnuts is not only black, but also when chestnuts are peeled off, it will be found that the germ of aged chestnuts has grown very long, while that of fresh chestnuts is very short.