Soybeans contain about 40 percent crude protein and 15 to 20 percent fat -- both highly perishable macronutrients -- making proper storage integral to a long shelf life. The shelf life of soybeans and soybean-based foods, such as flour and tofu, varies with their moisture content. For example, dehydrated soybeans can last up to 10 years when kept under proper storage conditions, whereas unshelled fresh soybeans last about one week.
Basic Storage Facts
Storage method ultimately determines soybeans' shelf life. Moisture content and temperature -- of both the storage container and the environment -- affect the rate of deterioration. Once soybeans begin to spoil, their oil becomes rancid and takes on a putty-like, waxy odor.
Keep unshelled soybeans and green shelled soybeans in airtight containers in the refrigerator up to one week. Dried and shelled soybeans last up to 12 months when kept in a cool, dry place. For long-term storage -- or over one year -- begin with clean, healthy soybeans. Maintain a temperature at or below 50 degrees Fahrenheit in an room with no more than 50 percent relative humidity.
Dehydrated soybeans last much longer than non-dehydrated soybeans -- from eight to 10 years. Dehydration involves reducing the soybeans' moisture level to about 2 to 3 percent. Store dehydrated soybeans in airtight containers in a room with a constant temperature, ideally lower than 70 F.
Soybean oil can last up to 12 months when stored in a dark, dry, cool area. If kept at room temperature in the kitchen, soybean oil stays fresh for about two or three months. Soymilk, a non-dairy, milk-like product made from soybeans, stays fresh for about one week in the refrigerator after opening. Refrigerated tofu lasts about three days in the refrigerator, while tofu in aseptic packaging, which does not require refrigeration, lasts about three days in the refrigerator after opening. Soy flour lasts up to seven months when stored in a sealed container in the refrigerator or freezer. Fat-free soy flour stays fresh longer than regular soy flour. Always refer to the manufacturer's label for recommended freshness dates and storage tips.