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Unsavory bacteria found in packaged lettuce

I’m someone who eats at least one salad daily, sometimes with prewashed packaged organic lettuce, so the findings from Consumer Reports’ latest tests on packaged leafy greens were not what I wanted to hear.

The magazine tested 208 samples of packaged salad greens (representing 16 brands) and discovered that a significant percentage contained unacceptable levels of two types of bacteria: total coliforms and enterococcus.

Those bacteria, which are found in the human digestive system, are considered “indicator organisms,” which means they’re used to determine if water, food, or something else has become contaminated with disease-causing fecal matter.

In other words, their presence is a sign of poor sanitation.

Specifically, Consumer Reports’ tests found that 39 percent of the sample greens exceeded the generally accepted industry standard (10,000 or more colony-forming units per gram) for total coliform and 23 percent exceeded the standard for enterococcus. (There are no federal indicator bacteria standards for salad greens, although such standards do exist for milk, beef and drinking water.)

There’s good news in the report, however. As Consumer Reports notes, indicator bacteria do not usually make healthy people sick. And the tests found no signs of the trio of truly dangerous bacteria: E. coli (0157:H7), listeria or salmonella.

But, then again, they weren’t expecting to find those particular pathogens. Their sample was too small. 

How much should we worry?
To find out just how concerned we should be about a report like this, I spoke with Joellen Feirtag, Ph.D., an associate professor in food science at the University of Minnesota.

Feirtage said she wasn’t at all surprised by Consumer Reports’ findings, as many such studies have been done before, with similar results.

Nor does she believe that people should stop eating packaged lettuce. “You probably aren’t going to get sick from this type of bacteria,” she said.

Yet these findings are another clear sign that we need to develop better systems for making sure food stays uncontaminated.“We need to be asking how we can reduce these indicators at the farm level,” Feirtag said. “If we reduce them, we’ll more likely also reduce or eliminate the pathogens,” such as E. coli, that do make us sick.

Part of the problem, she said, is that much of the produce we eat is grown on large farms in far-away places, such as California or South America.By the time the produce has reached us, it has had many opportunities to be improperly handled — and to permit any bacteria on it to grow.

“Ideally, you want fresher produce that hasn’t been traveling,” Feirtag said. But small, local farms are not always the answer, she added.“We’ve shown that there is no more safety in foods from smaller farms than in those from larger ones,” she said.

Nor is organic produce any safer in terms of bacterial contamination. (Indeed, the bacteria-contaminated national brands in the Consumer Reports study included Earthbound Farm Organic as well as such nonorganic brands as Dole and Fresh Express.)

What you can do
One of the problems with finding bacteria on lettuce, said Feirtag, is that the food is eaten raw, and thus there’s no chance to use heat to destroy the pathogens. “You’re not cooking the lettuce,” she said. “You might be able to rinse some of [the bacteria] off, but not all of it. ”

Still, both Feirtag and Consumer Reports recommend washing the lettuce anyway, even if the package says the greens have been “pre-washed” or “triple-washed.”

Here are some other suggestions.

  • Avoid packaged products with spinach. Most of the samples with a high bacterial count in the Consumer Reports study tended to contain spinach.
  • Buy packages that are as far away from their use-by date as possible. The longer greens have been out of the soil, the more time bacteria has to grow.
  • Rinse your greens as soon as you get them home.  Dry them, and then immediately store them in the refrigerator.
  • Keep your greens away from raw meat — including any utensil or cutting board that you use to prepare raw meat.

And, whatever you do, don’t stop eating salads. As the Centers for Disease Control and Prevention reported late last year, we’re eating way below the recommended three or more helping of vegetables and two or more helpings of fruit daily.

Nationally, the CDC reports, only 32.8 percent of us get enough fruit daily, and only 27.4 of us get enough vegetables. The numbers are worse for Minnesotans: 27.3 and 25.8, respectively.

And a pitiful 11.6 percent of Minnesotans (compared to 14.0 percent nationally) get enough healthful helpings of both fruits and vegetables daily.


Comments (1)

  1. Submitted by Arito Moerair on 02/04/2010 - 02:40 pm.

    Another day, another finding of contaminated food. World keeps spinning. I wonder if there will be another study that will find contaminated food. Nah. Someone will fix it.

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