The U.S. Food and Drug Administration recommended guidelines for food safety during power outages are as follows:
Food safety when the power goes out:
o Keep the refrigerator and freezer doors closed as much as possible to maintain the cold temperature. The refrigerator will keep food cold for about 4 hours if it is unopened. A full freezer will keep the temperature for approximately 48 hours (24 hours if it is half full) and the door remains cold. Buy dry or block ice to keep your refrigerator as cold as possible if the power is going to be out for a prolonged period of time. Fifty pounds of dry ice should hold an 18-cubic foot full freezer for 2 days.
o If you will be eating your refrigerated or frozen meat, poultry, fish or eggs while they are still at safe temperatures, be sure they are thoroughly cooked to the proper temperature to assure that any foodborne bacteria that may be present is destroyed.
o Wash fruits and vegetables with water from a safe source before eating.
o For infants, if possible, use prepared canned baby formula that requires no added water. When using concentrated or powdered formulas prepare with bottled water if the local water source is potentially contaminated.
Once the power is restored:
o Once the power is restored you will need to evaluate the safety of the food. If an appliance thermometer was kept in the freezer, read the temperature when the power comes back on. If the thermometer stored in the freezer reads 40 degrees F or below the food is safe and may be refrozen. If a thermometer has not been kept in the freezer, check each package of food to determine the safety. Remember, you can't rely on appearance or odor. If the food still contains ice crystals or is 40 degrees F or below, it is safe to refreeze or cook.
Refrigerated food should be safe as long as the power is out for no more than 4 hours. Keep the door closed as much as possible. Discard any perishable food (such as meat, poultry, fish eggs or leftovers) that has been above 40 degrees F for 2 hours.
For more information on safe food handling, call FDA's toll-free information line at 1-888-SAFEFOOD.