‘Prewashed’ Salads May Need Another Rinse

03 Feb

Consumer Reports Analysis Finds Bacteria in Packaged Green Salads

Those "prewashed" and "triple-washed" bagged salad greens that are on my salad plate at this very moment may not be as clean as I had hoped.

In a new investigation from the Consumers Union, which publishes Consumer Reports, high levels of bacteria commonly linked to poor sanitation and fecal contamination were found in many of the sampled packaged salads.

spinachWhile Consumers Union senior scientist Michael Hansen, PhD, states that the bacteria did not pose a health risk to the public, their presence indicated a higher likelihood of contamination with rare but potentially deadly pathogens like E. coli and salmonella.

An E. coli outbreak in the fall of 2006 traced to packaged fresh spinach killed three people and hospitalized more than 100.

Although the cause of the contamination was never confirmed, the E. coli was widely believed to have reached the spinach through groundwater that contained the feces of cattle and pigs.

Some Key Findings

Consumer Reports investigators sampled 208 packaged salads, representing 16 brands purchased last summer in Connecticut, New Jersey, and New York. The salads were sold in either bags or plastic clamshell containers.

  • 39% of the samples contained more than 10,000 "most probable number" per gram — a measure of total coliforms, which are bacteria associated with fecal contamination.
  • 23% had more than 10,000 colony forming units (CFU) per gram of the bacterium enterococcus.

    According to the report, experts contacted by Consumer Reports considered these levels unacceptable.

    • Bacteria levels varied widely, with some samples containing undetectable levels and others containing more than 1 million CFUs per gram, Hansen says.
    • Packaged produce tested at least six days from their use-by date tended to have lower levels of the bacteria than produce tested within five days of the use-by date
    • Salad mixes that included spinach tended to have higher bacteria levels than those without spinach. 
    • Contamination levels were similar whether the produce was packaged in a bag or clamshell container. And samples labeled "organic" were just as likely to have high levels of the bacteria as other samples. 
    • Little difference was seen in bacteria levels between larger, nationally distributed brands and smaller, regional brands. All brands with more than four samples had at least one package with relatively high levels of total coliforms or enterococcus.
    • Hansen says consumers should look for products that are at least six days from their use-by date when buying packaged salad products.
    • All products labeled "prewashed" or "triple-washed" should be washed again, even though this probably won’t remove all bacteria, he says.
    What should you do

    Consumer Reports recommends you follow these steps with all fresh produce:

    1. Although most fresh produce is safe to eat, it is prudent to treat all produce as if it could be contaminated.
    2. Keep it separated from other foods in your refrigerator, as to avoid cross contamination with other foods and to slow down bacterial growth. 
    3. Wash your hands with hot, soapy water before and after handling and dry them with paper towels. 
    4. It’s prudent to make sure to discard any areas that are turning brown or show the slightest evidence of spoilage.   
    5. All produce needs to be washed thoroughly in a stream of water to remove any dirt that can harbor bacteria.
    6. Even if you buy pre-washed or triple washed salads, you need to wash them again
    7. Produce washes do not claim to kill harmful bacteria.  Washing in water may work just as well.
    8. Use separate cutting boards and utensils for meats and produce and thoroughly clean the preparation area after cutting and dry with paper towels.

    The report was made public online this week and it appears in the March issue of Consumer Reports.

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    Posted by on February 3, 2010 in From the Kitchen, Health


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