Myth: Freezing will kill bacteria on food.

Answer: Busted!

Freezing does not kill bacteria, yeasts and molds present in food, but it does prevent their multiplication if the food is held at 0 degrees Fahrenheit or less. When thawed, the surviving organisms can multiply again. Some foods such as fresh vegetables are blanched before freezing. While blanching destroys some bacteria, sufficient numbers are still present to multiply and cause spoilage of the product when it thaws. For this reason, it is necessary to carefully inspect any frozen products which have accidentally thawed due to power outage or the freezer door being left open.

When the freezer has been off, the basic guide in determining a food’s safety is whether or not it still contains ice crystals. If it does, the food (except seafood) should be refrozen as quickly as possible. It is a good idea to mark each package with an X, label as “Refrozen,” or otherwise designate that these items should be eaten first and as soon as possible. If any food has thawed and there are no ice crystals in it, it should be thrown away. If there is meat juice on neighboring packages or at the bottom of the freezer, throw out any meat in question that may have thawed.

It is also OK to refreeze if the thermometer in the freezer reads 40 degrees F or less and if the power has been out for less than two hours. Once food has been above 40 degrees F for more than two hours, it should be discarded. This is also true if the power comes back on without realizing power was restored.

For more information, visit Missouri Families or the National Center for Home Food Preservation.

Contributor: Damaris Karanja, MA, Nutrition and Health Education Specialist, St. Louis County, University of Missouri Extension, Karanjad@missouri.edu