The following information is summarized from FDA and other sources. Further information on food safety during natural disasters can be found at: http://www.cfsan.fda.gov/~dms/fsdisas.html#s2.
General Food Safety of Refrigerated Foods
Refrigerated foods that can be held at temperatures above 40ºF until power returns include: hard cheeses, butter, margarine, fresh fruits, fruit juice, fresh unpeeled vegetables, salad dressing, ketchup, mustard, olives, pickles, jams, jellies and peanut butter.
For all other products, most refrigerated foods are safe if the power outage was only 2-3 hours and if foods were held above 40ºF for 2 hours or less; however, for those who were without power for several days, most refrigerated foods should be discarded. If you are unsure how long products have been held above 40ºF, DISCARD the products. Foodborne pathogens can grow very quickly in some foods held above refrigeration temperatures; visual appearance and odor cannot be used to assess the safety of food products.
General Food Safety of Frozen Foods
If foods still contain ice crystals, they can be refrozen safely. Thawed fruits, fruit juices and fruit pies will be safe to eat; however, discard these products if they have come in contact with thawed meat drippings or if they have signs of spoilage, such as off-odors due to fermentation. All other thawed foods should be discarded. PNW 296 – Freezing Convenience Foods, page 3 has information about safety of frozen foods that have thawed.
Appliance Maintenance during a Power Outage
It is recommended to have appliance thermometers in refrigerators and freezers to help assess product safety.
During a power outage, keep freezer and refrigerator doors closed as much as possible. Try to keep the cold air in the freezer (a large, full freezer can hold freezing temperatures for about 2 days, a half-full freezer will keep food frozen for about 1 day) and the refrigerator (if unopened, will maintain a cold temperature for approximately 4 hours).
If the power outage is expected to last for an extended period, dry ice and ice blocks can be used to keep foods cold. Handle dry ice with caution. Separate dry ice from food products using a piece of cardboard; place the dry ice on top of the cardboard. Fifty pounds of dry ice will keep a full, 18-cubic foot freezer cold for two days (a general rule is to allow 2-3 pounds of dry ice per cubic foot of freezer space).
Safety of Specific Food Products
Meat, poultry and seafood products, including hot dogs and lunch meat. Frozen meats that have intact ice crystals and have an internal temperature less than 40ºF may be refrozen. Variety meats, such as heart and liver, should not be refrozen under any circumstances. Meat products at temperatures above 40ºF for more than 2 hours are potentially unsafe and must be discarded.
Hard cheese, butter and margarine. Well packaged products should remain safe; if odors or mold develops, discard the items.
Milk products and mayonnaise. Discard if held above 40ºF for more than 2 hours. This category includes milk, cream, yogurt, and soft cheeses. Ice cream should be discarded if it has partially thawed.
Fresh Eggs. Discard if held above 40ºF for more than 2 hours.
Fresh fruits and vegetables. Normally safe. Observe appearance for mold, sliminess or yeasty smell, discard if appearance is poor.
Frozen fruits and vegetables. If ice crystals are still intact and food has remained at 40ºF or less, these products may be refrozen; otherwise, discard the product.
Fruit juice. Refrigerated juices are safe without refrigeration; however, if mold, cloudiness, bubbling or off-odors (yeasty, fermented) occur, the product should be discarded. Frozen juices with intact ice crystals or if held at 40ºF for less than 2 hours may be refrozen.
Salad dressing, ketchup, mustard, olives, pickles, jams, jellies and peanut butter. May be kept unrefrigerated until power returns.
Mixed food items, including cooked pasta, stews, casseroles, soups, potatoes, custards and puddings. Discard if held above 40ºF for more than 2 hours. This category includes leftover foods.