Michigan State University Extension
Preserving Food Safely - 01600673
Chestnuts are easily grown in southern Michigan and usually are of Chinese or Korean origin. They are quite similar to the native American chestnut, but are generally resistant to the blight that killed American trees. They should not be confused with horse chestnut which is closely related to the buckeye and not recommended for eating. Chestnuts available in stores during the fall are usually of European origin.
After picking, chestnuts are generally seasoned for several days to remove excess moisture and to retard formation of mold while being stored or shipped. This may be done by spreading the nuts 1 or 2 layers deep on trays made of 1/2-inch mesh hardware cloth. If seasoned 1 to 2 weeks under warm, dry windy conditions, the nuts may dry more than desired, especially if additional drying occurs during storage. If the shell can be pushed in a considerable amount when squeezed between the thumb and forefinger, the nut may have dried too much. Best results are obtained with plump nuts that have not been subject to mold.
If chestnuts are to be cooked within several weeks after picking, they do not need to be air dried. If they are to be eaten raw, they generally need at least a few weeks for the starch to slowly change to sugar. This process occurs in both air drying and refrigerated storage. If the nuts are picked and eaten immediately, some may have an astringent taste while others may not. Chestnuts of Korean origin tend to be more palatable when green than chestnuts of Chinese origin.