May 24, 2024

To Wash or Not to Wash: Are Pre-Bagged Salads Safe?

When producers introduced pre-washed, bagged salad mixes to the grocery store, more people started eating salads at home. All you have to do is open the bag and pour the salad into a bowl. No more washing and drying greens, which takes time (even with a Salad Spinner), sorting the greens and tearing them by hand.

Bagged Salad MixWhile the convenience is wonderful, many people have wondered: Are those prepackaged greens safe? There are two schools of thought on this matter. One group says to always wash greens, even if they’re in a bag that proclaims every leaf is “triple-washed.” The other insists that the greens are safe because they’re washed in a processing plant using far more sophisticated methods than are available in home kitchens. Here’s the problem: both camps have science to back up their claims.

The Pro-Washing Camp

Consumer Reports conducted a study in 2010 that lit a fire under this discussion. They tested 208 containers of 16 different brands of salad greens for bacteria and found that 39% of the packages exceeded safe levels for coliform bacteria, and 23% had unsafe levels of enterococcus bacteria. But they didn’t find any disease-causing bacteria that food safety experts worry about, such as Listeria, Salmonella, or E. coli 0157:H7.

The problem with the presence of coliform bacteria and enterococcus in the greens is that they are an indicator of poor sanitation methods and fecal contamination. There are no limits for these organisms in produce, but they’re used as a rough guide to possible pathogen contamination.

Scientists use the number of coliform bacteria to test water safety. The bacteria are harmless, but the EPA says “they are like police tape and chalk outlines … often found at the scene of a crime.”

And enterococcus lives in your GI tract, which is where it belongs. Not on salad greens, because it’s an indicator of the presence of fecal matter. If the bacteria on the greens is Enterococcus faecalis, you can get sick with urinary tract infections, blood in the urine, fever, and confusion.

The Department of Agriculture tested more than 4,000 samples of the bagged greens in 2008 and found Salmonella in two of those samples. The Food Safety Modernization Act set stronger safety standards for produce, including those contamination indicators. But putting rules and laws into practice takes time.

So where do those bacteria come from? Like all produce, greens are vulnerable to contamination from irrigation water, runoff from livestock, poorly sanitized equipment in processing sheds, and ill handlers. Remember that produce was the source of 1/3 of all foodborne illness outbreaks in 2011.

The processors say that “triple washed” salads are washed with fresh water and chlorinated baths. But it’s difficult to thoroughly clean lettuce, as anyone who has prepared a head of lettuce for a salad knows. Consumer Reports recommends washing pre-bagged salad greens.

The Anti-Washing Camp

In 2007, a study published in the journal Food Production Trends found that leafy greens in sealed bags with the “pre-washed” label from a well-run and properly inspected facility do not need re-washing. Unless the label directs you to rinse the greens. The authors of that study said that additional washing done by the consumer doesn’t enhance the safety of the product and could cross-contaminate the greens.

There are a whole lot of caveats in that statement. It seems that as long as you buy from a big brand name, trust the FDA, and make sure the bag is sealed and kept refrigerated, you’ll be okay.

Christine Bruhn, director of the Center for Consumer Research at UC Davis and co-author of the study, says that since consumers don’t triple wash their produce in chlorinated water, and since homes aren’t inspected by the FDA, washing pre-washed greens at home may contaminate perfectly clean greens with bacteria. In fact, improper food handling at home is one of the leading causes of foodborne illness.

We know that many consumers don’t follow food safety standards. In some kitchens, washing pre-washed salad greens may actually contaminate them.

Possible Solutions

One of the problems with mass-produced salad greens is that thousands of pounds are washed and then bagged together. And we all know that means one small amount of bacteria in one batch could contaminate thousands of pounds of greens.

The salad industry, like other food industries, is making changes. Taylor Fresh Foods, for instance, is implementing an ingredient called “Smart Wash”, an additive also called T-128, in their produce wash lines. The additive is made from Generally Regarded as Safe (GRAS) ingredients. Fresh Express is rolling out a “Fresh Rinse” solution. Industry researchers are looking at many different ways to clean greens, including radiation, citrus-based sanitizers, ultrasound, gaseous washes, and chlorine alternatives. The jury is out on whether these methods will help make salad greens cleaner.

So what can you do about it? You should eat dark leafy greens often because they’re packed with fiber, vitamins, minerals, and phytochemicals. But you want your food to be clean and free of contaminants.

  • If you choose to buy bagged salad greens, buy reputable, well-known brands.
  • Make sure the label says that the greens are ready-to-eat and have been pre-washed.
  • Only buy bags that are properly refrigerated at the store.
  • Reach into the back of the display case and choose a bag from the very back.
  • Buy bags with an expiration date as far in the future as possible.
  • Eat the lettuce before the expiration date; ideally, two to three days before that date. The closer the product is to the expiration date, the higher the bacterial counts.
  • Keep the bags refrigerated at all times.
  • If you do wash bagged greens, sanitize your sink first and wash your hands thoroughly.
  • Rinse the leaves or the whole head in clean, running water and dry, then use immediately.
  • Keep greens and other ready-to-eat foods well away from raw meats and eggs.
  • If you buy heads of lettuce, clean them thoroughly, also in a sanitized sink. Peel off and discard several outer layers of the leaves.
  • Don’t buy lettuce from an open bulk container.
  • You can use produce wash to clean the lettuce, but that doesn’t remove bacteria. It will remove oils, pesticide residues, and dirt.
  • When in doubt, throw it out!


  1. Hello,
    Thank you for the article! I liked particularly the last piece of advice, “When in doubt, throw it out!”.

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