Guest column

The power is out: is my food safe to eat?

Feb. 3, 2011

By Dianne Lamb

It’s that time of year when the weather can raise havoc with daily living because of ice, snow, wind or just plain cold temperatures. We often forget how much of our daily life is dependent on electricity. When the lights go out due to a power outage, life grinds to a halt and we feel trapped.

Power outages can occur at any time of the year for any number of reasons. Are you prepared? Do you know how to keep food safe when the power is out?

Let’s start at the beginning. To ensure that foods are kept at a safe temperature, refrigerators need to be set at 40 degrees Fahrenheit and freezers at 0 degrees. The best way to check is to keep appliance thermometers in the refrigerator and freezer at all times. These thermometers indicate the temperature even when the power is out, and no matter how long it has been out.

When you lose power, the first step is to try to keep refrigerator and freezer doors closed as much as possible to maintain cold temperatures. If not opened, the refrigerator will keep food cold for about four hours. A full freezer will maintain its temperature for approximately 48 hours (or half that time if half full), providing you don’t open the door.

If the power will be out for an extended period of time, add ice, if available, to keep the temperature of your refrigerator as cold as possible. Plan ahead for possible emergencies by knowing in advance which stores in your area carry block ice.

What else can you do ahead of time to store your food safely in an emergency?

If the power will be out for more than four hours, you can use coolers with frozen gel packs to store food. Or if your freezer is not full, you can group items close together as this will help the food stay cold longer.

Can food from the refrigerator or freezer be stored outside in the snow?

The answer is “no.” It is actually not a good idea because even when it is very cold outside, the sun may thaw frozen food. Food-borne bacteria can grow in refrigerated food that becomes too warm. Another big concern is that perishable foods stored outside may be exposed to unsanitary conditions or come in contact with animals that can harbor bacteria or disease.

So what should you do?

You can take advantage of the chilly temperatures by making ice. Fill empty milk cartons, buckets or cans with water and place outside to freeze. Then add your homemade ice to your refrigerator, freezer or coolers to keep food cold.

Another important thing to keep in mind is that you should never taste food to determine if it is safe to eat. This can make you ill. Instead, check the temperature in your freezer when the power is restored. If it reads 40 degrees or below, or if the food still contains ice crystals, you can refreeze the food. If you don’t have a thermometer in the freezer, inspect each package of food carefully. Remember, you can’t rely on appearance or odor.

Partial thawing and refreezing may reduce the quality of the food, but it will be safe to eat. However, always discard any items that have come in contact with raw meat juices. The same applies even when it is not a power outage but a malfunctioning freezer or someone failed to close the freezer door tightly and food has begun to thaw before the open door is discovered.

Refrigerated food should be safe as long as the power is out for no more than four hours. Keep the door closed as much as possible. Discard any perishable food, such as meat, poultry, fish, eggs, deli items, soft cheeses, milk and leftovers, that has been above 40 degrees for two hours or more. Some foods, including processed cheeses, butter and fresh fruit, will still be safe to eat.

Be prepared for an emergency by stocking items that don’t require refrigeration and can be eaten cold or heated on an outdoor grill. Always follow safe operating procedures when using the grill.

When you plan your emergency food supply, include shelf-stable food products — boxed or canned milk, water and canned goods, for example. Make sure you have ready-to-use formula for babies, and don’t forget your pets. They will need food and water, too, in an emergency. Since you don’t want these products to expire before you need them, use and replenish them periodically.

You’ll also want to have a hand-held can opener available for emergency use. If you only have an electric can opener, you won’t be able to use it if you lose power.

You never know when an emergency will occur, so be prepared. The U.S. Department of Agriculture’s Food Safety and Inspection Service website has information on what do in a power outage and charts outlining when to save and when to discard food. Since you may not be able to use your computer or call for information during a power outage, take time now to print out the factsheet at Keep a copy handy.

Knowing how to tell if food is safe and how to keep it safe will help minimize food loss and the potential risk of food-borne illness, not only in emergency situations but every day of the year. Remember, when it comes to food safety, the rule of thumb is, “When in doubt, throw it out!”

Dianne Lamb is the University of Vermont’s Extension Nutrition and Food specialist.