food during power outages

The Truth About Freezing and Thawing

By Diane Wright Hirsch, MPH, RD

UConn Extension Educator – Food Safety

inside freezer
As I am writing this, it is snowing lightly outside my office window. I am thinking about the potential weather fluctuations. Lots of folks have filled their freezers and refrigerators in preparation for the storm. But what happens when the power goes out?

This time of year (as opposed to hurricane season), we are lucky that the temperatures are such that we can use the out of doors as one huge refrigerator/freezer. Over the next 8 days it looks like temperatures in my neck of the woods won’t reach much over thirty—and then only for a day or two and then it is back to the deep freeze.

One question I frequently get after a widespread power outage—or, at any time, really—is, “Is   it ok to refreeze food that has defrosted.” Many have been scared into thinking that once a food thaws, it is no longer safe to refreeze or, maybe, even to eat. So, let’s go through two possible defrosting/refreezing scenarios and use a bit of food safety science to explain what happens and what is your best course of action. Before we go any further, though keep in mind that having a couple of food thermometers on hand will help you to make food safety decisions. It would be best if you have one in the freezer (so you can tell if your freezer is still capable of freezing!). Also, have on hand a food thermometer—the same kind that you can use for checking to see if food has cooked to the proper temperature. This thermometer will tell you the actual temperature of the food you are checking on: this is not so important if the food is frozen, but once it defrosts, it can help you with the should I keep it or toss it question.

Your electricity is out—no freezer or refrigerator.

One tool, actually two, that will help you with this is the thermometer.

Once the food defrosts, try to keep it cold by keeping it in the freezer/refrigerator (or outside if it is cold enough). As long as the food stays at 40 degrees F or below, you can refreeze it within a day or two, or maybe even three (fish, ground meat and poultry and similar food with high perishability should be refrozen within 24-48 hours).

Alternatively, cook and/or eat it while it still registers 40 degrees F or below on the thermometer. If both your freezer and refrigerator are out of service, then keep in mind that you should only cook what you can eat – there will be no way to cool down the leftovers for refrigeration.

Keeping Food Safe During a Power Outage

Clemson leftovers
Photo: Clemson Extension

When the power flickers and then completely goes out, your first instinct is to find a flashlight or light candles. Being able to see is a priority but, what you may not know is that bacteria will begin growing in perishable foods when the electricity is off.

During the winter season, severe snow and ice storms damage outdoor utility lines, and storing food safely becomes a challenge if the power goes out. The U.S. Department of Agriculture (USDA) recommends these steps to follow before and during a power outage.

Prepare Ahead of Time

  • Appliance thermometers. Make sure you keep appliance thermometers in both the refrigerator and the freezer. That’s the best way to be sure that your food is safe after a power outage. Safe temperatures are 40 °F or lower in the refrigerator; 0°F or lower in the freezer.
  • Freeze water in one-quart plastic storage bags or small containers. They are small enough to fit in around the food in the refrigerator and freezer to help keep food cold and won’t make a mess when the ice melts. Don’t fill them too full. Because water expands when it freezes, the bags might split. Make extra ice at home.
  • Freeze refrigerated items such as leftovers, milk and fresh meat and poultry that you may not need immediately. This helps keep them at a safe temperature longer.
  • Dry ice or block ice. Know where you can get them.
  • Have coolers on hand to keep refrigerator food cold if the power will be out for more than 4 hours.
  • Group foods together in the freezer; this helps the food stay cold longer. They form an “igloo” to protect each other.
  • Don’t put food outdoors in ice or snow because wild animals may be looking for a meal, and when the sun comes out it may warm your food to an unsafe temperature.
  • Stock up on ready-to-eat foods. Be sure to have a few days’ of foods that do not require cooking or cooling.

When the Power Goes Out

  • Keep the refrigerator and freezer doors closed as much as possible. A refrigerator will keep food cold for about 4 hours if the door is kept closed.
  • A full freezer will hold its temperature for about 48 hours (24 hours if half-full).
  • Place frozen meat and poultry on a tray so that if they begin thawing, their juices will not drip on other foods.
  • Buy dry or block ice if the power is going to be out for a long time. Ice will keep the refrigerator as cold as possible. Fifty pounds of dry ice should keep a fully-stocked 18-cubic-feet freezer cold for two days.

When Power Comes Back On

  • Check the temperature inside your refrigerator and freezer. Discard any perishable food (such as meat, poultry, seafood, eggs, or leftovers) that has been above 40 °F for two hours or more.
  • Check each item separately. Throw out any food that has an unusual odor, color, or texture, or feels warm to the touch.
  • Check for ice crystals in frozen food. The food in your freezer that partially or completely thawed may be safely refrozen if it still contains ice crystals or is at 40 °F or below.
  • Never taste a food to decide if it’s safe.
  • When in doubt, throw it out.

See these charts to help you evaluate specific foods

For more information about food safety in an emergency, check out these resources:

  • A Consumer’s Guide to Food Safety: Severe Storms and Hurricanes (USDA)
  • Video Link: Food Safety During a Power Outage
  • In an Emergency (FoodSafety.gov)