Sprouts and bagged salad greens: What food safety experts steer clear of to avoid E. coli

An E. coli outbreak that has sickened at least 75, killing one, is a reminder of the contamination risk that can plague certain types of fresh produce, according to food safety experts.

The four professors said they routinely avoid particular raw fruits and vegetables themselves, such as sprouts, bagged salad greens and cantaloupe.

Though the investigation is ongoing, federal officials suspect prewashed, slivered onions that were served raw on McDonald’s Quarter Pounders are the likely source of the E. coli outbreak. For those who specialize in foodborne illness prevention, the news was not a surprise.

Don Schaffner, a professor of food science at Rutgers University, said that the more food is handled and processed on its journey from the farm to a restaurant or grocery store, the more opportunities there are to introduce or spread bacteria. That includes slicing, prewashing or adding ingredients.

“The more manipulation you do, certainly the more places there are for things to go wrong,” Schaffner said.

By nature, when fruits and vegetables are served uncooked, there’s no opportunity to heat away bacteria. This has contributed to past E. coli outbreaks linked to produce, including a 2006 outbreak in prepackaged baby spinach that sickened over 200 and dozens of instances of E. coli and other foodborne illnesses that have been associated with contaminated sprouts. Cantaloupe also has been contaminated with pathogens, including salmonella and listeria.

“If you look at just the sheer number of outbreaks and recalls over the last 15 years, we typically see more cases of E. coli tied to produce,” said Darin Detwiler, a professor of food regulatory policy at Northeastern University.

Although there were serious E. coli incidents decades ago in meat — including an outbreak linked to Jack in the Box hamburgers that made hundreds of people ill and killed four in the early 1990s — changes to federal regulations and a better understanding of proper cooking temperatures needed to kill off the bacteria have reduced those cases.

Barbara Kowalcyk, director of the Institute for Food Safety and Nutrition Security at the George Washington University Milken Institute School of Public Health, said that she makes an effort to avoid eating bagged greens, sprouts and cantaloupe. Bags or containers that hold lettuce or other leafy greens can seal in bacteria and create an environment for it to proliferate, she said, so for salads, she opts for heads of lettuce at the grocery store instead.

“Any leaf that is torn or damaged, I just throw it away, because that’s how the bacteria can get in there,” she said. “And I usually take the outer leaves off and discard them.”

She then thoroughly washes and dries the lettuce.

“The key is running water and using a clean paper towel to dry it,” she said. “The bacteria are kind of sticky, and friction is what gets them off.”

Schaffner said previous E. coli outbreaks involving prewashed, leafy greens resulted from not enough chlorine in the water as they were being rinsed. With sprouts, it’s a different concern, he said: The seeds are exposed to warm temperatures and, as they sprout, release nutrients into the water that allow bacteria to grow.

Cut melons, meanwhile, can be a common breeding ground for pathogens, especially if they’re left sitting out.

“I do a lot of workshops, and they often have cut fruit on the breakfast buffet, and that fruit just sits there all day long,” Schaffner said. “We’ve done research to show that the physical appearance of it doesn’t change, but it can grow bacteria like nobody’s business.”

Detwiler is particularly careful to avoid cantaloupe because of its webbed rind, where bacteria can easily hide.

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