Michigan State University Extension
Preserving Food Safely - 01600671
Spread nuts thinly on trays or screens and allow them to dry gradually from exposure to a gentle but steady air flow. A clean, cool, dry porch or attic is ideal. Nuts dried this way will not mold. Drying times varies with nut variety. Most varieties will need several weeks for proper drying. All nuts except chestnuts contain a large amount of oil which prevents them from drying out completely. Because of their high water and carbohydrate content, chestnuts dry in 3 to 7 days. Drying for longer will cause chestnuts to become hard and inedible.
-Nutmeats of pecan, walnuts, filberts and hickory nuts should shake freely in their shells.
-Nutmeats should be light-colored and break with a sharp snap when bent or bitten.
-Taste should be light-flavored.
-Note: Excessive drying will cause nut shell to crack.
Alternative drying methods:
Small amounts of nuts in the shell can be dried in a furnace room or even on trays on a radiator providing the temperature do not exceed 100 degrees Fahrenheit. Temperatures above 100 degrees Fahrenheit will affect flavor and shorten storage life. Nuts will be dry in 24 to 48 hours.
Nuts in the shell can also be dried in a food dehydrator if the temperature can be adjusted low enough. Follow manufacturer's directions. Unshelled nuts will dry in 8 to 10 hours in a food dehydrator.
Oven drying is not recommended for unshelled nuts as it is difficult to keep the temperature low enough and air circulation is poor.