What to toss—and what to keep—next time there's an electrical outage.

By Claire Gillespie
August 05, 2020
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It's the season for stormy weather, which puts the electricity powering your refrigerator at risk. A brief power outage lasting minutes won't affect the quality of the food in your fridge or freezer. But what about electrical outages lasting hours or days—how long does the fridge stay cold, and at what point does bacteria growth become a threat, forcing you to toss out your perishable food? Here's everything you need to know.

How long will my fridge stay cold? 

Without power, a refrigerator will likely remain at a safe temperature for up to four hours if the door is kept closed, Tamika Sims, PhD, director of food technology communications at the International Food Information Council, tells Health. Food in your freezer stays cold for even longer—about a day if the freezer is half full, and about 48 hours if it’s full (the more food there is inside, the more cold is retained). 

But don’t be tempted to check on your foods every few minutes, as this will accelerate the temperature increase—and therefore the spoiling. “It’s crucial to keep your refrigerator and freezer doors closed during power outages to maintain the cold temperature,” Sims says. 

How will I know when food in my fridge starts to go bad?

During a power outage, you can use appliance thermometers in your refrigerator and freezer to help determine if your food is safe. “Normally, refrigerator temperature should be 40 degrees Fahrenheit or lower, and the freezer should be 0 degrees Fahrenheit or lower," Sims says. If there’s not a thermometer inside the appliance to gauge temperature, you can use a food thermometer on each item to work out if it’s safe to eat. 

While some foods, like dairy and meats, might start to look or smell bad, you can’t always rely on the appearance or smell of a food item to determine its safety. “For items in the freezer to be safe to refreeze or prepare for consumption, they should have an internal temperature below 40 degrees Fahrenheit,” Sims says. 

“If meats, eggs, or leftovers have been above 40 degrees Fahrenheit for more than two hours, it’s time to throw them out,” Sims advises. This quick guide of various food groups from foodsafety.gov, a website from the FDA, CDC, and other federal health agencies, can give you an idea of what to keep and what you should toss. But checking the actual temperature of the food in your refrigerator will ultimately tell you what is safe to eat. 

Sims advises always erring on the side of caution. So if you’re unsure about the safety of food items that were in your refrigerator or freezer during a power outage—or anytime, for that matter—it’s better to throw them away and rely on shelf-stable pantry items for your meals.

And to avoid food waste, it’s wise to eat the most perishable items in your refrigerator first, such as leftovers, meat, poultry, and foods containing milk, soft cheese, cream, or sour cream, assuming their temperatures indicate they are safe.

How to keep food from spoiling if the outage lasts more than a day

If it’s likely that power will be out for several days, purchase dry ice or block ice for your refrigerator or freezer to help keep perishables at a safe temperature.

But don’t put your food outside to keep it cold, even during winter. The New York State Department of Health warns that temperatures cold enough for refrigerated food are still too warm for frozen food. It may be very cold outside, but the sun could still heat the food to a temperature that would cultivate bacteria.   

How to keep food safe before the power goes out

Long before the storm hits, you can take steps to help maximize the lifespan of your refrigerated and frozen foods. The New York State Department of Health advises grouping frozen foods in a protective “igloo,” keeping meats together on one side of the freezer or on a tray so that if they start to thaw, their juices (which could harbor bacteria) won’t mix with other foods. Remember, foods with a high water content, such as meat or fruit, will stay frozen longer than food with a low water content, such as bread.

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This story originally appeared on health.com.