What is growing in your refrigerator or freezer?

Temperature control and cleanliness are critical in keeping Listeria under control in your kitchen.

The bacteria Listeria has been in the news a lot lately, linked to ice cream, frozen vegetables and fruit. Unlike most bacteria, Listeria can grow and multiply in your freezer and refrigerator. This is surprising to some. Listeria can also be found in soil, water, and some animals, including poultry and cattle. It can also be present in raw milk and foods made from raw milk. Listeria has been known to survive in processing plants and contaminate a variety of processed meats, including ready-to-eat deli meats, hot dogs and meat spreads. These bacteria can be killed by proper cooking and pasteurization.

One group of people most at risk for listeriosis (the illness caused by Listeria monocytogenes) is pregnant women. In pregnant women, listeriosis can cause miscarriage, stillbirth and serious illness or death of newborn babies. Other groups at risk for listeriosis include older adults, people with compromised immune systems and those with certain chronic medical conditions, like HIV/AIDS, cancer, diabetes, kidney disease and transplant patients. Symptoms of the infection include fever, stiff neck, confusion, weakness, and vomiting, sometimes proceeded by diarrhea. The incubation period can be 3 to 70 days, and the illness may last days or weeks depending on the health of the person prior to the illness setting in.

So how do you protect yourself from listeriosis? The first step of defense is to wash all fruits and vegetables under running water just before eating, cutting or cooking, even if you plan to peel it first, this includes everything from oranges to onions to bananas. Scrub firm products such as melons and cucumbers with a clean produce brush. 

Avoid drinking raw milk (milk that has not been pasteurized) or consuming foods that have unpasteurized milk in them. Persons in the high-risk groups should heat deli meats, hot dogs and cold cuts before eating them.

Chilling food properly is another important step to reduce the risk of Listeria infection. Although Listeria can grow at refrigeration temperatures, it grows more slowly at temperatures of 40 degrees Fahrenheit or less. Making sure certain foods do not leak juices onto other foods to avoid cross-contamination is another way to protect food, cover all food or wrap in plastic wrap or foil before placing it in the refrigerator. Utilize a refrigerator thermometer in the center of the fridge and check periodically. Adjust the temperature control if necessary to keep foods at or below 40 degrees F. Use pre-cooked and ready-to-eat foods as soon as you can.  The longer they are stored in the fridge, the more chance Listeria has to grow. Perishable and ready-to-eat foods should be consumed as soon as possible, if you are storing leftovers, they must be consumed or disposed of after three days.

It is also important to clean your refrigerator and freezer regularly. Listeria can contaminate other food by spills, especially from meat juices. Use paper towels to avoid transferring germs on a cloth towel. Clean the inside walls and shelves of your refrigerator with warm water and liquid soap, then rinse. You can also sanitize monthly using 1 teaspoon of unscented bleach to 1 quart of water. Put in a spray bottle, spray the surface, let it stand for 10 minutes, wipe with a clean paper towel. Let air dry.  Remember bleach solutions become less effective with time so discard unused portions daily.

Last but not least, clean hands and kitchen surfaces often. Listeria can spread from one surface to another.

Michigan State University Extension recommends keeping your perishables cold, wiping up the spills in your refrigerator immediately, using your perishables in a quick timely manner and keeping a thermometer in your fridge and freezer to monitor temperatures. Following these simple food safety guidelines will help ensure your family stays healthy.

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