From the Research
Freezing does not kill Listeria monocytogenes bacteria, and it is not a reliable method to make contaminated food safe to eat. Unlike many other foodborne pathogens, Listeria can survive and even grow at refrigeration temperatures (as low as 0°C/32°F) and remains viable when frozen at -18°C/0°F or below 1. This means that freezing food contaminated with Listeria will not eliminate the risk of listeriosis. The bacteria will become dormant during freezing but will become active again once thawed.
To effectively eliminate Listeria, foods must be cooked to an internal temperature of at least 74°C (165°F). This is particularly important for high-risk foods like deli meats, soft cheeses, unpasteurized dairy products, and ready-to-eat refrigerated foods. Pregnant women, older adults, and immunocompromised individuals should be especially cautious as they face greater risk from listeriosis 2. Proper food handling, thorough cooking, and avoiding high-risk foods when in vulnerable groups remain the best prevention strategies, as freezing cannot be relied upon as a method to kill this resilient pathogen.
Some key points to consider:
- Listeria can cause severe infection in vulnerable patients, including sepsis and meningitis, and can be fatal 1.
- Contaminated meats, dairy products, and seafood have all been implicated in outbreaks of listeriosis 2.
- The public health importance of listeriosis is not always recognized, but it ranks among the most frequent causes of death due to foodborne illness 2.
- Educational information and proper labeling of ready-to-eat meat and poultry products can help reduce the risk of listeriosis 3.
Overall, proper food handling and cooking are crucial to preventing listeriosis, and freezing should not be relied upon as a method to kill Listeria.