Food lasts 4 hours in refrigerator if there is no power

During a power outage, an appliance thermometer is invaluable to test the temperature of food in the refrigerator and freezer, U.S. health officials said. Officials at the U.S. Food and Drug Administration said in case of a power outage, the appliance thermometers will indicate the temperatures in the refrigerator and freezer to help you determine if the food is safe -- the freezer temperature should be at or below 0 degrees F and the refrigerator should be at 40 degrees F or below. If the power does go out, keep the refrigerator and freezer doors closed as much as possible to maintain the cold temperature. A refrigerator will keep food cold for about 4 hours if it is left unopened. A full freezer will keep the temperature for approximately 48 hours -- or 24 hours if it is half full -- if the door remains closed, officials said. When the power comes back on, check the temperature in the freezer and if it reads 40 degrees F or below, the food is safe and may be refrozen, FDA officials said. "If a thermometer has not been kept in the freezer, check each package of food to determine its safety. You can't rely on appearance or odor," the FDA said on its website. "If the food still contains ice crystals or is 40 degrees F or below, it is safe to refreeze or cook." Discard any perishable food -- such as meat, poultry, fish, eggs or leftovers -- that has been above 40 degrees F for 2 hours or more, the FDA said. Perishable food such as meat, poultry, seafood, milk and eggs not kept adequately refrigerated or frozen might cause illness if consumed, even if thoroughly cooked, the FDA said.