E. coli sprouts traced back to raw flour



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Eggs, which for a long time were condemned for making raw cookie dough a forbidden pleasure, may stop taking all the blame. There is another reason to resist the sweet raw temptation: flour.

The seemingly innocuous staple food can harbor strains of E. coli bacteria that make people sick. And, although it is not a particularly common source of foodborne illness, flour has been implicated in two E. coli outbreaks in the United States and Canada in the past two years.

Post contaminated flour as the source of the US outbreak The US, which made 63 people sick between December 2015 and September 2016, was more complicated than average food poisoning. Researchers report on November 22 in New England Journal of Medicine.

Health departments generally rely on standard questionnaires to find a common culprit in a group of reported diseases, says Samuel Crowe, an epidemiologist at the Centers for Disease Control and Prevention in Atlanta, who He directed the study. But flour is not usually tracked in these surveys. Then, when the initial investigation yielded inconclusive results, public health researchers turned to in-person personal interviews with 10 people who had become ill.

Crowe spent two hours asking each person detailed questions about what he had eaten around the time of getting sick. Asking people what they ate eight weeks ago can be a challenge, Crowe says: Many people can not even remember what they ate in breakfast that morning.

"I had a bit of luck," says Crowe. Two people remembered eating raw cookie dough before getting sick. Each of them sent Crowe pictures of the bag of flour they had used to make the mix. It turned out that both bags had been produced in the same plant. That was something "quite unusual," he says.

The follow-up questionnaire helped Crowe and his team fix the meal as the probable source. Finally, scientists from the US Food and Drug Administration. UU They badyzed the flour and strains isolated from E. coli bacteria that produce Shiga toxins, which produce E. coli dangerous.

Bacteria causing disease, including E. coli generally thrive in moist environments, such as bags of pre-washed lettuce ( SN: 12/24/16, p.4 ). But bacteria can also survive in a desiccated state for months and reactivate with water, says Crowe. Then, as soon as the dry flour is mixed with eggs or oil, the inactive bacteria can be reactivated and begin to replicate.

Cookie dough was not the culprit in all cases. Some children who became ill received raw tortilla dough to play while waiting for a table in a restaurant. All cases involved wheat flour from the same facility, which led to the recall of more than 250 products containing flour.

There are ways to kill the bacteria in the flour before they reach the shelves of grocery stores, but they are not used in the United States. The heat treatment, for example, will rid the flour of E. coli and other pathogens. But the process also changes the structure of the flour, which affects the texture of the baked goods, says Rick Holley, a food safety expert at the University of Manitoba in Canada who was not part of the study. Irradiation, used to kill parasites and other pests in flour, could be a better option, says Holley. But a higher dose of radiation is needed to kill the bacteria than to kill the pests.

Or, of course, people could expect fresh baked cookies.

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