Frozen doesn’t mean Listeria – Free

The food industry has been increasingly focused on a risk-based approach to food safety. Control of Listeria specifically, is always at the top of every list, as it poses the largest threat. “The pathogen’s recent influx in a variety of fresh, frozen and processed foods is reinforcing the importance of understanding how contamination occurs in processing plants.” (Mackin, 2018).

While most frozen foods are meant to be cooked, it is not uncommon for the average consumer to use frozen fruit and vegetable products in cold salads, and other prepared foods consumed without cooking first. Benjamin Chapman, a food-safety specialist and an associate professor at North Carolina State University noted, “Though eating raw, frozen vegetables may sound unusual, frozen kale, for example, is increasingly being used in smoothies. And it’s not uncommon for pediatricians to recommend letting young children chew and suck on frozen veggies while teething.” (quoted in Miller, 2016). Chapman went on to clarify that although freezing may stop Listeria growth, it doesn’t necessarily kill the organism (Miller, 2016).

As frozen food processors evaluate risk, and implement changes, the freezers themselves present unique challenges:

  • Design- there are many areas of freezers that are difficult to reach or are inaccessible. Due to the size of the units, they cannot be disassembled completely for a thorough cleaning. Freezer coils tend to be difficult to reach, difficult to clean, and expensive to replace if damaged.
  • Compatibility- Many freezers are made of metals such as aluminum that can be easily damaged by common products used for cleaning and sanitizing. As the damage occurs, it creates even more harborage points for microorganisms and additional cost for the processor.
  • Temperature- As the freezer is defrosted for thorough cleaning, the warmer temperatures allow existing Listeria to grow. The condensation created from the thaw can also contaminate other surrounding surfaces.

How can this be addressed? The industry is working toward better equipment design, not just for freezers, but for all equipment used in food manufacturing.
Additionally, the industry has recognized the need for cleaning and sanitizing chemicals that are effective in addressing the shortcomings of current equipment design, and products that are compatible with aluminum and other soft metals.

Sterilex Ultra Disinfectant Cleaner Solution 1 and Ultra Soft Metal Activator is a disinfection chemistry specifically designed to kill specific organisms such as Listeria as well as remove biofilm* on aluminum surfaces. It can be used to safely disinfect freezer surfaces while moving into inaccessible areas where biofilms are harbored.

Miller, Sara G. “Listeria in Your Freezer: How Long the Bacteria Survive.” LiveScience, Purch, 25 May 2016,

Mackin, Kelsey M. “South Dakota scientists target Listeria in food processing plants.” Food Safety News, 14 Feb 2018,

*Biofilm label claims approved for specific applications only. See product label for full label claims and usage instructions.

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*Biofilm label claims approved for specific applications only. See product label for full label claims and usage instructions.

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