Will Cooking Kill E Coli Bacteria On Vegetables

The Public Health Agency of Canada is over again telling Canadians not to swallow romaine lettuce in Ontario and Quebec, and now New Brunswick. Health officials in the U.S. and believe the outbreak can be traced back to California.

The Public Health Agency of Canada is advising people in Ontario and Quebec not to eat romaine lettuce subsequently an outbreak of Due east. coli. (Justin Sullivan/Getty Images)

The U.Due south. Food and Drug Administration believes it has traced the source of the latest E. coli outbreak linked to romaine lettuce. It says based on aircraft records and invoices, the lettuce appears to have come from California — specifically the Central Coast growing regions of northern and central California

Earlier this calendar month, the Public Health Bureau of Canada brash Canadians in Ontario, Quebec and now New Brunswick not to eat romaine lettuce while the investigation was underway.

This was the third outbreak in Northward America suspected to exist linked to romaine in the past year. Co-ordinate to the Microbiology Club, 20 to 30 per cent of outbreaks of E. coli poisoning are acquired by people eating contaminated vegetables. Lettuce and other leafy greens are often the culprits. Hither's why:

How it's grown

Lettuce needs a lot of irrigation water during tillage. And sometimes the root of the trouble is as simple equally cantankerous-contamination on the farm where it's beingness grown.

"You lot can get contamination from brute production facilities, it gets into the sediment, information technology gets into the water, which gets irrigated onto the crops, which are then harvested within 40 to 80 days," says Keith Warriner, a microbiologist specializing in food prophylactic at the University of Guelph.

The way lettuce is grown contributes to its susceptibility to contamination. (Ted Southward. Warren/Associated Press)

The bacteria can as well come up from birds flight overhead or other wildlife walking through fields. And, short of moving all product into greenhouses, it's only very difficult to avoid that kind of contamination. Information technology's equally hard to pinpoint the source.

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"By the fourth dimension public health officials are notified, people have been sickened for a long time," said Lawrence Goodridge, professor of food safety at McGill Academy." And he said, since the shelf life of lettuce is quite short — nearly five weeks — information technology may not even be in circulation any longer.

Raw versus cooked

But it'southward not just lettuce and leafy greens. There is currently a salmonella outbreak in western Canada linked to cucumbers. What do these all take in mutual? Consider this: when was the last time you cooked your lettuce or cucumbers?

That'south another basic reason why people more often get ill from eating contaminated lettuce and other salad greens. Unlike many other vegetables, they are rarely cooked before being consumed. Cooking kills Eastward. coli O157 and other leaner. And so other vegetables may be getting contaminated just as lettuce is, but because the vegetables are mostly being cooked, at that place is no widespread outbreak of illness.

What about washing?

Washing the produce at home is not a reliable way to remove bacteria.

"The bacteria can be stuck on the surface of the lettuce, information technology can fifty-fifty get within the lettuce," Goodridge says. "So if you wash it, you might remove some of the bacteria, but you're not removing 100 per cent. And we know in some cases, when we look at historical outbreaks of East. coli, fifty-fifty ingesting 1 single bacterial prison cell was plenty to cause disease."

What about pre-washed packaged lettuce?

If you tend to reach for the convenience of pre-washed, pre-cut greens, you've probably seen on the packaging that it says they've been double- or even triple-washed. But Goodridge says, again, when it comes to E. coli, that means nothing.

New Brunswick joins provinces affected by E. coli linked to romaine lettuce

"Information technology'south washed to remove clay, and chlorinated h2o is used, but really, that doesn't practice much. In fact, studies have shown information technology tends to spread the contamination around." And what'south worse, he suggests, when the lettuce is cut in the processing plant, the leafage releases sugars that the bacteria like to grow on. So the bacteria can multiply even faster.

Consider, likewise, he says, that to get to that bag or box, the lettuce has gone through a lot of hands and a lot of machinery, all of which could be harbouring leaner, too.

A microscopic epitome shows colonies of E. coli bacteria grown on an agar plate. (U.S. Centers for Disease Control via Reuters)

Why is lettuce contamination so hard to prevent?

It's a question beingness asked by many scientists.

"Those of us who work in this area, we have much work to do to try to figure out why this apparently seems to keep happening," Goodridge says. "Is at that place something specific well-nigh romaine lettuce that perhaps now of a sudden in the past twelvemonth has elevated information technology, or is information technology but a coincidence?"

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At the Academy of Guelph, there may be the ancestry of some answers to that.

'We've actually got some current research going on here that suggests, of all the different lettuce types, Due east. coli O157 likes romaine lettuce," Warriner says, "especially if it is breaking out of its dormant state. So there is an clan with leafy greens and E. coli O157. People advise it's a pathogen-vegetable interaction going on, where they're actually adapted to living on lettuce."

Minus any conclusive findings, though, both scientists concur information technology'south not worth the risk to swallow romaine lettuce right at present. If you have information technology, they say, throw it out. And don't buy any or order it in a eating house for the fourth dimension being.

The National's health panel talked about the latest lettuce contamination this week:

The National'south wellness console talks lettuce

If yous fear your lettuce might be contaminated with E. coli, there is no point in trying to wash the bacteria away - just throw it out, say the doctors on the National's heath panel. And and then clean your fridge. 2:44