The USDA's office of Food Safety and Inspection Service suggests preparing ahead of time by keeping an appliance thermometer in the refrigerator and freezer. In the case of a power outage, the thermometer can help assess the safety of the food. The freezer should be at 0 degrees F (Fahrenheit) or below and the refrigerator should be at 40 degrees F or below.
In addition, you can freeze containers of water for ice to help keep food cold in the freezer, refrigerator or coolers after the power is out. Freeze refrigerated items such as leftovers, milk and fresh meat and poultry that you may not need immediately to keep them fresh longer.
Make sure you have coolers on hand to keep refrigerator food cold if the power will be out for more than four hours. The USDA suggests purchasing or making ice cubes and storing them in the freezer for use in the refrigerator or in a cooler, and freeze gel packs ahead of time for use in coolers.
To help keep food cold longer, group food together in the freezer. Keeping block ice or dry ice in the refrigerator and freezer will help keep it as cold as possible if the power is going to be out for a while. The agency says fifty pounds of dry ice should hold an 18-cubic-foot full freezer for two days.
Close the Door
Keeping the refrigerator and freezer doors shut as much as possible saves energy, and it's especially important during a power outage to maintain the cold temperature. The USDA says a refrigerator will keep food safely cold for about four hours if it is unopened. A full freezer, meanwhile, will hold the temperature for approximately 48 hours (24 hours if it is half full and the door remains closed).
If the power has been out for several days, check the temperature of the freezer with an appliance thermometer or food thermometer (hopefully you prepared ahead and have one in there!). If the food still contains ice crystals or is at 40 degrees F or below, the food is safe. If the food still contains ice crystals or is at 40 degrees F or below, it may be safely refrozen.
If a thermometer has not been kept in the freezer, then check each package of food to determine its safety. The USDA says if the food still contains ice crystals, the food is safe.
When in Doubt, Throw It Out
Discard refrigerated perishable food such as meat, poultry, fish, soft cheeses, milk, eggs, leftovers and deli items after four hours without power. You'll be glad to be reminded that you should not taste a food to determine its safety! Remember the mantra: When it doubt, throw it out.
For more information on food safety, visit the USDA FSIS Website.