Will my frozen milk go bad in a power outage?

If there is a power outage, will your frozen breast milk sour? It’s unlikely your breast milk will go bad. Fortunately, most power outages are short-lived. And freezers are built to stay cold for 24 hours or more, as long as you keep the freezer door tightly closed and open it only when absolutely necessary. Each time you open the door, cold air escapes and the inside temperature rises. As long as the freezer temperature stays at 32°F (0°C) or less, your milk will remain frozen. Breast milk that is partially thawed (slushy) can be refrozen as long as it contains ice crystals. On the other hand, milk that is completely thawed (in other words, it is liquid) must be used within 24 hours. 

Many freezers will keep foods frozen for several days. But if the power hasn’t been restored within 24 hours you may want to consider Plan B. Either transfer your breast milk to a functioning freezer at a friend’s home, or place it in an insulated cooler with dry ice (frozen carbon dioxide). Dry ice can be found in most grocery stores. It has a surface temperature of -109.3°F (-78.5°C) and turns into a gas (carbon dioxide) rather than a liquid when it breaks down, making it ideal for cold storage. Exercise caution when using dry ice. Wear heavy gloves to protect your skin from the super cold temperature and place the insulated cooler in a well-ventilated space where the carbon dioxide gas can easily escape.

You can minimize the effects of a power outage on your stored breast milk by taking 3 simple steps: 

  • Set the thermostat in your refrigerator and freezer at the appropriate temperature. The temperature in your freezer should be 23°F (-5°C) or below; the temperature in your refrigerator should be at or below 39°F (4°C). 
  • Store your breast milk in the back or bottom of the freezer compartment of a refrigerator/freezer, upright freezer, or chest freezer. Pack frozen items in front of your milk (upright freezer) or on top of your milk (chest freezer). Use homemade ice packs (plastic freezer bags partially filled with water) to fill any empty space. The less air you have inside the freezer the longer it will take the freezer to warm up in the event of a power outage. 
  • Consider purchasing a small, gasoline-powered generator to keep your freezer running during a power outage. Prices start at $300.

The same guidelines that apply to milk stored in the freezer, apply to milk stored in the refrigerator: 

  • Place your milk in the back of the refrigerator away from the door. 
  • Reduce air space by surrounding the milk with other food items. 
  • Keep the refrigerator door closed, opening it only when absolutely necessary. 
  • Consider Plan B if the power hasn’t been restored within 24 hours and the containers of milk are approaching 39°F (4°C).

Last updated November 13, 2018

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