Michigan State University Extension
Preserving Food Safely - 01600674
If properly stored, chestnuts may be stored in a refrigerator for several months. Chestnuts dry rapidly in dry air and mold rapidly in damp air. For refrigerator storage, first place the chestnuts in a closed paper sack and leave for 1 to 2 days until they have reached refrigerator temperature. Then transfer them to a sealed plastic sack and punch about a dozen holes in the plastic with a medium sized nail. A good method for storing freshly harvested chestnuts in a refrigerator is to use milk cartons and dry peat moss (as it comes from the package). If the chestnuts are separated by the dry moss and the package tightly closed, the nuts should stay in good condition for several months. Freshly dug sand can also be used. Use sand that has been dried in the sun with occasional mixing until it is only very slightly damp. The sand should be cooled before use in the milk carton. Sand also keeps chestnuts in good viable condition for 2 years by storing the freshly picked chestnuts in sealed plastic bags and maintaining a temperature of 26 degrees Fahrenheit to 30 degrees Fahrenheit. (This temperature range requires special refrigeration).
If molding occurs in the refrigerator, the nuts may be washed and/or scrubbed to remove mold, and placed on paper toweling- with 1 or 2 paper changes- and then allowed to room dry for several hours. After drying, place again in a paper sack in the refrigerator until they are chilled, then transfer to a clean plastic bag with holes punched in it. If mold persists on the nuts for an extended period of time, the kernels may become "off-color" and no longer edible. If mold has been present, any bad kernels can be spotted by cutting the nuts in half before cooking.