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Research finds some E. coli survive cooking temperatures

In the wide, wide world of Escherichia coli, some might say the pathogen will eventually survive fire and others might say it will survive ice.

But more important than any of that is the need to cook hamburger to more than 160 degrees and always use that meat thermometer.

Professor Lynn McMullen

Professor Lynn McMullen, a food microbiologist at the University of Alberta, and her colleagues found some strains of E. coli can survive the recommended cooking temperature of 160 degrees F (71 degrees C).

June 2 news release about some otherwise fairly obscure research involving the University of Alberta suggests some strains of E. coli survive the 160-degree F recommendation that has been the rule of thumb in Canada and the United States for years.

The microbiologists studying E. coli  are from both Alberta and China’s Huazhong Agricultural University, and they’ve been at for years. There are a lot of E. coli to study. Here’s what the researchers say:

“Escherichia coli are commensals in the human and animal gut but the species also comprises intestinal and extraintestinal pathogens. The ecological versatility of E. coli is reflected in its genome plasticity. The average E. coli genome is approximately 5.16 Mb, encoding an average of 5190 genes.

“The core genome of E. coli comprises about 1700 genes (Kaas et al., 2012); however, the pan-genome of E. coli contains more than 18,000 genes and is still considered to be open (Rasko et al., 2008; Touchon et al., 2009; Kaas et al., 2012).”

The microbiologists then took  “29 strains of E. coli that differed in their heat resistance” and analyzed them by comparative genomics. About 2 percent were found to be heat resistant. Only seven strains of E. coli are banned from beef because they are considered a danger to human health.

All of the University of Alberta’s research strains were non-pathogenic, not a danger to human health. Genome databases the researchers consulted suggest heat resistance might also exist in some pathogenic strains. Some of the findings apparently have yet to be replicated by other researchers.

Yet, the press release both calls Health Canada’s recommendation of cooking ground beef to a minimum of 160 degrees F (71 decrees C) into question and suggests heat resistance could be the reason for sporadic cases of E. coli.

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