Black mold in a freezer should never be a problem because the evaporative coils that suck warmth from the air also remove moisture, which mold needs to survive. However, if the door seals are compromised or the door gets opened frequently and moisture-laden air can get in, mold will take an opportunity to establish itself on relatively warm areas, such as the door gasket or the light.
Black mold (S_tachybotrys chartarum_) is dangerous anywhere in the house, but it's especially dangerous when it's growing near food because mold on food in the fridge or freezer can make you sick. Not all the mold that grows in freezers is Stachybotrys, and many varieties aren't dangerous (or blue cheese wouldn't be a thing), but the Centers for Disease Control and Prevention doesn't recommend trying to make a distinction. If you see mold growing anywhere, especially where food is present, you should remove it.
What's the Best Cleaning Solution for Mold in the Freezer?
If you do any research on mold remediation, you'll come across recommendations to wash it with bleach. There are good reasons for not following this advice when trying to remove mold from porous surfaces, but for the smooth, non-porous surfaces inside a freezer, bleach is an effective mold cleaner. If you're going to clean a moldy fridge with bleach, the CDC recommends a mixture of no more than 1 cup of bleach per gallon of water.
There's no single best way to clean a deep freezer. If you prefer, you can forget the bleach and use safer chemicals that won't leave a lingering odor in the freezer. These include:
- Hydrogen peroxide – Fill a spray bottle with 3 percent hydrogen peroxide and spray it directly on the mold.
- Vinegar – The miracle condiment can kill 82 percent of all mold species. Spray it full strength for best results.
- Baking soda – Deodorize while you kill mold by putting a quarter tablespoon in a spray bottle of water and spraying the mold.
- Detergent – The Environmental Protection Agency recommends detergent and water for mold removal, followed by a disinfectant treatment if necessary.
How to Remove Mold in the Freezer
After you choose the cleaning solution you want to use, unplug the freezer, remove all the food and wait for the compartment to come to room temperature and all the frost to melt. Clean out all the water with a sponge to expose the mold you need to clean.
Scrub the mold with a sponge or rag. If you use a spray bottle to apply the mold cleaner, have a bucket of water handy so you can rinse the rag or sponge frequently. Pay special attention to the door gasket because this is where mold is most likely to grow. It's a good idea to remove the gasket and wash it separately.
You'll also want to remove anything else not permanently attached and wash them separately as well. This includes ice trays, vent covers, food racks and light covers. Use a toothbrush to scrub around the door hinges and any other place that's hard to reach.
How to Prevent Mold From Growing Back
Once you're done scrubbing and rinsing, let the freezer compartment dry out completely. Mold needs moisture to grow, but as long as the freezer is working properly, there shouldn't be any moisture, and you want to keep it that way. Check the door seals and replace them if they're worn, and limit the number of times you open the freezer door.
A good way to reduce moisture in the freezer is to keep it full. If frozen food is occupying all the available space in the freezer, there's no room for moist air to circulate. If you don't have enough food, fill the compartment with something else, such as plastic bottles full of water.