I have a small freezer in the garage for extra pints of ice cream and frozen leftovers. Compared to the main freezer in my kitchen, the food I pull from the garage is always frozen rock-hard. Should I be concerned that my kitchen freezer isn’t cold enough? This question had me curious about what temperature I should be setting the freezer to and if there’s anything I can do to keep my food safe. Here’s what I found out.
According to the U.S. Food and Drug Administration, the best temperature for your freezer is 0°F (-18°C) or below. If your freezer has a built-in thermometer, it’s easy to set and track the temperature.
To be certain your freezer is actually at the temperature you set it to, you can buy an inexpensive appliance thermometer to monitor it.
Here’s another smart trick: “If you want to know if your freezer works without a thermometer, you can put a cup (eight ounces) of water [in the freezer] and see if that freezes completely in an hour,” says Kumar Mallikarjunan, Professor and Director of Graduate Studies in the Food Science and Nutrition Department at the University of Minnesota, and member of the Institute of Food Technologists’ refrigerated and frozen foods division. “If it does not, your freezer is not holding its temperature.” It’s time to have it checked out by an appliance expert.
Some freezers only have numbers, not a temperature, like zero to five. In this case, you should use the coldest setting, which is five, says Mallikarjunan.
Why It’s Best To Keep Your Freezer’s Temperature at 0°F or Colder
If your freezer’s temperature is at 0°F or below, you don’t have to worry about the food in it becoming unsafe to eat.
“Freezing to 0°F (-18°C) does not kill bacteria; however, it does help with preventing it from growing,” says Tracy Fink, Director of Scientific Programs and Science and Policy Initiatives at the Institute of Food Technologists. “It helps with inactivating microbes, including such polymers as mold, yeast, and fungi in food.”
Unless the temperature in a food rises above 39.2°F (4°C), there’s no worry about microbes growing, adds microbiologist Jason Tetro, host of the Super Awesome Science Show and author of The Germ Code and The Germ Files.
At 0°F or below, you can also avoid freezer burn. When food thaws and refreezes—in the scientific community this is called a freeze/thaw event—ice crystals form on it. “That crystallization is a form of freezer burn that decreases the flavor quality,” Fink explains
“If food isn’t cold enough, the quality can decline as water melts and recrystallizes,” adds Tetro. “At low temperatures, the crystals are small and have little effect on the product. As the temperature rises, the ice crystals can grow and alter the quality of products like meats and ice cream.”
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Can the Temperature Be Too Low?
You can always err on the safe side and lower the temperature below 0°F—your freezer can never be too cold.
“Most recommendations are for a range of temperatures but in reality, there is no temperature that is too low for freezers,” says Tetro. “Most freezers do have a lower limit of around -10°F (-23°C).”
Being extra cold may only mean it takes longer for your ice cream to soften up. Fink adds that “a freezer set below 0°F (-18°C) will not make food unsafe to eat [or harm your food], though it may raise your energy bill due to using extra power.”
How You Store Food in the Freezer Impacts Its Temperature
To help regulate the temperature in your freezer, make sure it is full but not packed. The U.S. Department of Energy suggests putting bags of ice in the freezer if there’s not much in there, but make sure there’s enough room for chilled air to circulate the food to keep it frozen.
Each time you open the freezer door, the temperature can fluctuate several degrees, which can affect the food closest to the open door. That is why it’s best to store food that is most impacted by temperature fluctuations away from the door.
“If you have multiple drawers/cabinets, it would be better to keep meat and seafood in the bottom (or back) to avoid them experiencing temperature effects,” suggests Mallikarjunan.
Fink specifically calls out the importance of keeping ice cream away from potential temperature changes. “It is recommended that ice cream be stored at as cold of temperature as possible,” she says. “We never want to give it a chance to melt,” form ice crystals, and decrease in quality.
Simply Recipes / Ciara Kehoe
How To Avoid Freezer Burn
It’s so disappointing when you open a carton of ice cream or a pouch of frozen chicken and see the tell-tale crystals of freezer burn. It’s safe to eat these, but they may taste off.
“Freezer burn happens when the food is exposed to dry air (low humidity),” says Mallikarjunan. “To avoid this, you should [package the food properly to] prevent moisture loss.” Tightly wrap the food with plastic wrap and/or foil or store it in an airtight container, like freezer bag, other freezer-safe plastic or glass container, or a sealed vacuum bag.
If possible, squeeze out as much air as possible from the container. “For food quality, the best option is to reduce the amount of air in any sealed package such as a freezer bag,” suggests Tetro. “And minimize the amount of air that can get into packages such as ice cream by making sure the seal is tight.”
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