Freezing food is one of the oldest and most effective ways to preserve food. It is a valuable tool we use to lengthen the shelf life of many foods. Even though freezing does not kill the bacteria that cause food poisoning or spoilage, it stops their growth; thus, the food stays safe and edible for extended periods. However, improper freezing practices can lead to microbial growth, freezer burn, and loss of quality, all contributing to food waste.
Interestingly the freezing temperature to maintain food safety is actually 0°F (-18°C), not 32°F when water freezes. This is because water and foods freeze differently. Foods are a complex mixture of many substances, like sugars, muscle tissue, water, and air, all of which influence the freezing process.
How is freezing good for food safety? Freezing stops the growth of microbes by halting their metabolic activity, meaning the cells become dormant. While microbes are generally not killed by freezing, they cannot actively grow or reproduce. Also, microbes need water to grow. When food is frozen the water inside it turns into ice crystals. As a result, microbes cannot use the frozen water as a water source.
Freezing is not considered a lethality step in food processing. Bacteria like Listeria and Salmonella survive refrigeration and freezing temperatures. Proper cooking after thawing is still essential to kill any harmful bacteria.
Freezing food is one of the oldest and most effective ways to preserve food. It is a valuable tool we use to lengthen the shelf life of many foods. Even though freezing does not kill the bacteria that cause food poisoning or spoilage, it stops their growth; thus, the food stays safe and edible for extended periods. However, improper freezing practices can lead to microbial growth, freezer burn, and loss of quality, all contributing to food waste.
Once it is time to cook frozen food, there are several safe ways to thaw it: in the refrigerator, in cold water, in the microwave, or as part of the cooking process.
Refrigerator Thawing
- Plan ahead, it can take at least one day to thaw every 5 pounds of food
- Place food on a plate or in a container to catch any leaks
- Put frozen meats on the bottom shelf to avoid cross contamination
- Cook within 3 days
Cold Water Thawing
- Put the food in a leak-proof bag or container
- Submerge package in cold tap water
- Change the water every 30 minutes
- Cook immediately after thawing
Microwave Thawing
- Place food in a microwave-safe container
- Follow your microwave’s instructions; use the defrost setting
- Cook immediately after thawing
When there is not enough time to thaw frozen foods, it is safe to cook foods from the frozen state. However, cooking will take about 50% longer compared to thawed foods.
Freezing is an essential tool for food safety and preservation; both quality and nutritional value are maintained while food waste is reduced. Even if freezing only stops the growth of bacteria, it is still a great technique to help keep food safe. Following proper freezing and thawing practices will reduce the risk of foodborne illnesses.