What's the connection between bagged salads and salmonella?

Bagged Salads and Greens: A Salmonella Risk?

For busy cooks, bagged salad greens are an advantage. They’re pre-washed, which makes it easier to put dinner on the table faster. For some people, there’s no soaking, rinsing, or drying the leaves in salad a spinner.

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But bagged salads could be harboring a dirty, and possibly deadly, secret: They provide a rich breeding ground for a pathogen associated with foodborne illness.

It’s Not Easy Being Green: Salmonella Risk in Bagged Greens

Leafy greens should be part of any healthy diet, whether you lightly cook them or toss them with other veggies in a salad. They’re great sources of vitamins, minerals, and other important nutrients. But that’s not all bagged salad greens might contain. According to a recent laboratory study, the environment inside these plastic bags might help foster the growth of salmonella, a type of bacteria that is a leading cause of food poisoning.

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Researchers at the University of Leicester in the United Kingdom conducted experiments in which they smashed a variety of salad greens sold in plastic bags, including green lettuce, red romaine lettuce, and spinach.

They then analyzed how these salad “juices” acted in a moist, warm environment that mimicked the environment found in plastic bags. The investigators found that salmonella growth increased 2,400-fold in the damaged leaves, compared to in whole leaves. They believe that the juices formed by smashing the leaves made salmonella more likely to adhere to them.

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Should You Bag It? Risks Associated with Bagged Salad

So should you pass on bagged greens? Not necessarily. Although this study found that damaged leaves in moist environments are more apt to attract salmonella, it did not actually show that all bagged salad greens are contaminated with this type of bacteria. (However, previous reports have identified E. coli and other bacteria in some bagged greens.)

If you choose to use bagged salad greens, take these sensible precautions:

  • Wash your hands thoroughly with soap and water (always after using the bathroom) and before preparing or eating food.
  • Store bagged greens in the refrigerator to keep the moist environment in check.
  • Wash salad greens before eating them, even if the label reads “pre-washed” or “triple-washed.” To clean your salad, place your greens or lettuce into a large bowl that contains a few inches of cold water. Swish the leaves around the bowl. Dirt and debris will sink to the bottom of the bowl, while the leaves will float.
  • Discard leaves that look damaged.
  • Eat the greens before the “use-by” date on the bag.

For more information, or to find a primary care doctors, visit www.UPMC.com/PCP or call 1-855-676-UPMCPCP.