Monday, February 15, 2010

Guest Blog: Reducing E. coli O157:H7 In Frozen Ground Beef

The following Guest Blog first appeared on Safety Zone, a regular blog feature on the site, and is reproduced here with the kind permission of its author, Dr. James Marsden.

Retail Frozen Ground Beef Patties and Risks of E. coli O157:H7

It's time to recognize that retail frozen ground beef patties pose an increased risk to consumers and take steps to reduce that risk.

If you conduct a Google search using the words “frozen ground beef patties and E. coli”, you will see that this product category has been implicated in an inordinate number of cases, outbreaks and recalls. The Topps recall and other highly publicized events over the past several years resulted from contaminated frozen ground beef patties. The October New York Times story that described a devastating illness that resulted from E. coli O157:H7 contamination also involved retail frozen ground beef patties.

Frozen ground beef patties were also implicated in the 1993 Jack-in-the-Box outbreak and other early public health events involving E. coli O157:H7. Fast food chains have taken steps to assure the safety of frozen beef patties, including raw material and finished product testing, the implementation of validated cooking processes that fully inactivate E. coli O157:H7 and process control measures that guarantee proper cooking every time. These systems have been effective in controlling the problem in fast food restaurants and other restaurants that use frozen beef patties.

The problem still exists when consumers prepare retail frozen ground beef patties at home. This is because frozen patties are inherently difficult to cook uniformly and sufficiently to control pathogens. If all consumers were educated about the risks associated with frozen beef patties, and took the same steps that have been successful in restaurant preparation, the problem would be solved. This would require that great care be taken when cooking frozen beef patties and the universal use of thermometers to verify that the cooked product has reached a minimum temperature of 160 degrees F. Efforts to inform and encourage consumers to adhere to these practices should continue. However, it is not realistic to expect that all consumers will apply perfect cooking methods when preparing frozen ground beef patties. The risk of E. coli contamination in these products has to be reduced upstream.

Here are 6 steps that I believe would make frozen ground beef patties safer for consumers:
  1. Assure that beef carcasses are processed to minimize the risk of pathogen contamination.
  2. Apply a validated intervention to chilled beef carcasses prior to fabrication.
  3. Test beef trimmings for E. coli O157:H7 using N-60 sampling procedures at slaughter plant.
  4. Apply at least one validated intervention to beef trimmings before grinding.
  5. Adopt a test and hold policy for finished frozen ground beef patties that applies to every production lot (Microbiological testing procedures now allow for results in less than 24 hours).
  6. Implement a prominent labeling statement for frozen ground beef patties with consumer information that underscores the importance of proper cooking (in addition to safe handling labels).

These steps in addition to continued efforts to identify and implement pre-harvest interventions and carcass pasteurization technologies would reduce the risk of E. coli O157:H7 in retail frozen ground patties and also help restore consumer confidence in beef products in general.

About Jim Marsden: Dr. James L. Marsden is Regent's Distinguished Professor of Food Safety and Security at Kansas State University, and the senior science advisor for the North American Meat Processors Association. He is the past president of the American Meat Institute Foundation in Washington, DC and a graduate of Oklahoma State University.

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  1. Does this mean that because of spoilage to fresh meat products, this test & hold policy is not
    applicable on fresh meats? Or is it necessary to
    immediately cook fresh meats without freezing to be as safe as possible from E.coli 157:H7 contamination? As a consumer, I've pretty much
    stopped purchasing ground meat period at this point, but would like to know safest procedure with fresh meats, also. Thank you.

  2. @Anonymous. The guest author was addressing frozen ground beef patties, specifically. The short shelf life of fresh meat cuts makes "test and hold" more difficult to apply effectively.

    Fortunately, fresh meat cuts are less likely to be contaminated with E. coli O157:H7 (or Salmonella, for that matter), because bacteria are SURFACE contaminants of meat. The reason that ground beef is such a problem is that the meat is ground up, spreading contamination throughout the package.

    Some "fresh" meat cuts, however, have been "tenderized", which means that they have been poked with tiny needles and may also have been injected with a tenderizing solution. This usually applies to meat supplied to restaurants (this practice was behind the recent National Steak and Poultry outbreak).

    In a restaurant, I would always ask for my meat well-done. At home, I'm more comfortable with a less well-done steak.

    The safest procedure with any meat or poultry is to verify the "done-ness" using a meat thermometer.

    BTW, freezing stops spoilage, but makes little or no difference to survival of E. coli O157:H7 or Salmonella, both of which can survive freezing. The only assurance of safety is adequate cooking. USDA has a good web page with recommended end-point temperatures for various types of meat (

  3. Thank you for the safe handling tips. I'm still going to avoid ground meat period for a while
    until things improve and now have two digital meat thermometers. Plus I now bathe whole meat cuts in boiling water for 30 seconds before further cooking. Consumers (me) appreciate your
    many efforts and have healthier families!

  4. @Anonymous. You're very welcome, but there's no need to go overboard. The first thing that gets cooked in a whole cut of meat is the outside. You can safely eliminate the boiling water bath.


  5. In regard to the short shelf life of fresh ground beef, many fresh beef grinder operators incorporate an N-60 pre-test of the trimmings lots on the receiving side. That is, they require a negative result for E.coli 0157:H7 to be done on each lot while the trailer of trimming combos is in transit from the slaughter operator to the grinder operator location before it can be accepted for use. Therefore, no positive analysis lots are allowed in the door. Acceptable negative analysis lots are then ground and manufactured into patties. Many of these grinders will not do "Test and Hold" analyses on the finished ground beef patty lots due to the short shelf life. The inherent problem with N-60 testing (at receiving of trimmings or finished product Test & Hold)is that it is not fool proof. E.coli 0157:H7 organisms are not uniformly distributed throughout a meat combo of individual trimmings. As a result an analysis of a combo may be negative when tested by a slaughter operator but could then later result in positive results of patties when tested by USDA or other agencies.

  6. @Anonymous. Thanks for sharing this. Your explanation adds weight to Dr. Marsden's argument that the only way to minimize the risk of E. coli O157:H7 contamination in ground beef is to mandate a whole carcass treatment (such as irradiation, high pressure, or some other "pasteurization" process).


  7. Yes, I am in agreement with Dr. Marsden's proposal. The control of E. coli 0157:H7 needs to begin upstream with an effective whole carcass treatment process at the slaughter location. Current slaughter E. coli 0157:H7 intervention processes have not been totally effective.

  8. thanks for listing down the 6 steps that believe would make frozen ground beef patties safer for consumers...this is indeed helpful to mom like me who just want to have a safe food in my family..
    Digital Meat Thermometer

  9. I'm actually of the opinion that as America's obsession with food grows - as evidenced by the popularity of all the cook off reality shows - we'll see smaller, local restaurants give the chains a run for the money. Small chef-owned restaurants with smaller, focused menus are serving up great casual food using locally sourced ingredients.


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