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Your Burgers Are Still Done at 71

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the November 2018 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

Maintaining consumer confidence is crucial to our industry. Consumer confidence in the safety of Canadian beef was briefly shaken by the 2012 XL Foods E. coli outbreak that infected at least 18 people, and resulted in the recall of 1,800 tonnes of beef, a $4 million legal settlement and the sale of the packing plant to JBS Canada. That event also led to a resurgence in media interest in E. coli research. Articles in both and the National Post featured interviews with researchers who expressed concern that Health Canada’s recommendation to cook hamburger patties to an internal temperature of 71oC may not be adequate to kill some strains of E. coli. These concerns stemmed from papers published in 2011, 2015 and 2016 that studied the genetics of heat resistant E. coli strains that had survived carcass washing interventions in a commercial beef processing facility in 2001 and 2002.

These concerns deserved serious investigation. In response, the Beef Cattle Research Council and Alberta Agriculture and Food supported a study led by Mark Klassen (Canadian Cattlemen’s Association) and Xianqin Yang (Agriculture and Agri-Food Canada’s Lacombe Research Station) to assess whether changes to Health Canada’s cooking recommendations were warranted. A panel of five additional scientists was assembled to review and approve the experimental design and methods before the research started.

What they did:

Nine E. coli strains (both pathogenic and nonpathogenic strains) were tested for heat resistance under laboratory conditions. The most heat resistant strain was incorporated into beef patties by adding approximately 100 million E. coli bacteria per patty. The burgers were cooked to Health Canada’s recommended internal temperature of 71oC, allowed to cool for 3 to 5 minutes, then the number of viable E. coli were evaluated.

What they learned:

No E. coli survived after the burgers were cooked to the recommended internal temperature 71oC and cooled for 3 or 5 minutes, even though the beef had been artificially contaminated with very high levels of E. coli.

Burgers aren’t eaten straight off the grill; it takes a few minutes to carry them inside, gather the kids, melt the cheese, pass the relish, etc. The burgers continue to cook during the first part of this “cooling period”. In this study, internal temperatures continued to rise for 2 minutes after they came off the grill, sometimes reaching as high as 75oC, and maintained at least 71oC for another 2 minutes after that. This extended the length of time E. coli is exposed to lethal temperatures.

What it means:

Health Canada’s cooking recommendations are still valid. Your burger’s still done at 71. That means at least “medium”. Using a meat thermometer is highly recommended to ensure the proper temperature is attained.

This study found that cooking burgers to 71oC killed all the E. coli, even though it had been contaminated with extremely high levels of bacteria. Results may have been different if the burgers had been cooked to a lower internal temperature. Cooks and servers should never ask their families or guests “how” they would like their burgers cooked, even if they’re using a “source grind” burger or ground the beef themselves. Do them, yourselves, and our entire industry a favor – let them know that medium-rare or rare hamburger is not a risk worth taking. Medium to well-done is the only option for burgers.

Canada’s beef industry has made tremendous progress in combating E. coli in packing, further processing and retail sectors. However, beef is not the only potential source of E. coli. The Canadian Food Inspection Agency’s website reports that there have been 11 E. coli O157 related recalls since January 2014, but only one of those recalls involved beef. That means that cross-contamination from other foods in the same shopping cart, bag, refrigerator, kitchen or grill can also pose an E. coli risk to consumers. To reduce the risk posed by E. coli O157, cooks in homes or commercial kitchens need to keep it cold (refrigerate meat as soon as it arrives and refrigerate leftovers as soon as possible), keep it clean (wash hands, surfaces and utensils frequently when handling food – and always between handling meat and other food) and keep it covered (keep meat and meat products separate from other foods).

In Canada’s National Beef Strategy, the first target outcome under the Competitiveness pillar’s “Supportive Regulatory Environment” focus area is to advocate and uphold a scientific risk-based regulatory system. This project is an important illustration of how industry expertise and public researchers can work together to effectively address an emerging food safety concern and objectively determine that more stringent Health Canada recommendations would not effectively improve food safety. The Canadian Beef Cattle Check-Off has increased from $1 to $2.50 per head in most provinces, with approximately 75 cents allocated to the Beef Cattle Research Council to support work like this. Canada’s National Beef Strategy outlined why the Check-Off increase was needed, and how it would be invested.

The Beef Research Cluster is funded by the Canadian Beef Cattle Check-Off and Agriculture and Agri-Food Canada with additional contributions from provincial beef industry groups and governments to advance research and technology transfer supporting the Canadian beef industry’s vision to be recognized as a preferred supplier of healthy, high quality beef, cattle and genetics.

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