Foods can become contaminated with harmful microorganisms by food handling mistakes during harvesting, processing, transporting to a market, preparing and storing. These harmful microorganisms can be pathogens (illness-causing bacteria), molds and toxin-producing bacteria.
Freezing does not kill harmful microorganisms that may be present on food from mistakes in food handling. At temperatures below 0 degrees Fahrenheit, these harmful microorganisms cannot grow or multiply on food.
Frozen foods must be thawed safely to prevent the growth of microorganisms as the temperature of the food increases. Thawing foods safely limits how much time a food spends in the Temperature Danger Zone. The Temperature Danger Zone is between 41°F and 135°F. This temperature range is ideal for pathogen growth. For example, some pathogens will double in number every 15 to 20 minutes in this zone. The risk of foodborne illness increases as the number of pathogens grows.
Safe thawing should be used for all foods, including fruits and vegetables.
Four methods to safely thaw frozen foods
Thaw in the refrigerator
This is the best method to thaw frozen foods because the internal temperature of the food will not increase above 41°F, which is the temperature of the refrigerator.
- Place the frozen food in a container to catch any leaks that may occur as the food thaws.
- Once thawed, cook or use the food within 2 to 3 days.
Thaw in cold water
This method is faster than thawing in the refrigerator but should be limited to foods that can be thawed in less than 4 hours.
- Place the frozen food in a leak-proof container or plastic bag to prevent splashes or leaks that can spread pathogens.
- Place the food under cold running water or submerge in cold water. If submerging the food, change the water every 30 minutes to keep the temperature cool.
- Foods thawed in cold water may thaw unevenly. The outside temperature will increase quicker than in the center. The outside temperature may increase to above 41°F, which is why it is important to limit the time needed for thawing.
- Once thawed, cook or use the food immediately to prevent pathogen growth.
Thaw in the microwave
This method can be used to thaw foods that will be cooked immediately after microwaving.
- Microwaves can heat food unevenly. Parts of the food may be heated into the Temperature Danger Zone while other parts remain frozen. Pathogens can grow rapidly at this temperature.
- Thoroughly cook foods immediately after thawing to kill pathogens.
Thaw as part of the cooking process
Some foods can be cooked directly from frozen without impacting quality.
- As the food thaws, it will pass through the Temperature Danger Zone rapidly as the food cooks.
- Cook foods to their minimum internal temperature to prevent foodborne illness.
Use safe food handling practices and cook foods thoroughly after thawing.
USDA. The Big Thaw - Safe Defrosting Methods, 2013. https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/big-thaw-safe-defrosting-methods
Reviewed in 2023