Pathogen control in ground beef

Production and consumption

Ground beef is a staple in the American diet.  The average American consumes nearly 28 pounds of ground beef per year, totaling about 10 billion pounds of ground beef produced in the U.S. annually.  More than 1,000 plants located in all 50 states produce fresh beef and ground beef.  It is estimated that about half of this ground beef (5 billion pounds) is sold through foodservice outlets, such as fast-food restaurants.  The remaining 5 billion pounds is sold through supermarkets.  A recent study showed that ground beef accounts for about 15 percent of supermarket meat department beef sales.

Some ground beef sold in U.S. supermarkets is ground fresh in the store, often from more than one source of fresh beef.  Many stores buy “coarse-ground” beef from their suppliers, then re-grind the beef into a finer grind before packaging it for the meat case.  Some stores mix this coarse-ground beef with trimmings from other beef products they cut and package in the store.  Other stores may grind beef exclusively from fresh beef trimmings produced from cutting and packaging beef products in the store.  During the last 10 years, an increasing amount of ground beef in the supermarket is processed and packaged for final sale in U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) inspected facilities, rather than in the supermarket.  This process produces a ground beef product commonly referred to as “case-ready.”

Ground beef safety

In addition to beef companies’ own quality and safety monitoring efforts, thousands of USDA inspectors are in beef packing and processing plants to ensure that the products are safe and properly labeled.  Fresh beef products are tested in meat plants for generic Esherichia coli, for Salmonella and for E. coli O157:H7 by FSIS.  In September 2011. FSIS announced that being in March 2012, six additional shiga toxin-producing E. coli (O26, O111, O103, O45, O145 and O121)  will be considered adulterants, like E. coli O157:H7, in non-intact beef products like ground beef.

All U.S. meat and poultry plants are required to meet strict sanitation requirements and to abide by mandatory preventive food safety production plans, called HACCP plans, to ensure that they are addressing all possible risk and biological, physical and chemical hazards that may exist in their facility during the production.

USDA and state officials also sample ground beef in U.S. supermarkets for E. coli O157:H7.  Any ground beef product that tests positive for this pathogen must be recalled from the market.  Also in March 2012, retail establishments will be testing for the six additional shiga toxin-producing E. coli.

FSIS routinely samples ground beef for E. coli O157:H7.  According to FSIS, E. coli O157:H7 occurs at a rate of less than one quarter of one percent, which has steadily declined since 2000. While it is rare for E. coli O157:H7 to find its way into products, it can occur, making careful handling and through cooking critical.

Prevalence of E. coli O157:H7 in Ground Beef

Microbiological results of raw ground beef products analyzed for Escherichia coli O157:H7.

In 1998, FSIS began taking samples of ground beef that were 15 times larger than previous samples. In June 1999, the agency implemented a new more sensitive test method for E. coli O157:H7.  In 2008 and 2011 more sensitive enrichment and sample size were implemented.  Why is this important?  Well, as technology advances so must our methods to detect microorganisms.  These changes have made the methodologies more sensitive or do a better job of finding the microorganisms when present.  These enhancements to the sampling and testing protocol have provided a greater number of positive samples. This is likely attributable to better detection methods, not greater prevalence of the pathogen.  In fact, since these enhancements to detection methods have been implemented, there has been a decline in the percent of positive samples.

Advice for consumers

Consumers should follow the safe handling practices detailed on every package of raw meat and poultry and should take special care to cook ground beef products, such as hamburger and meat loaf, to an internal temperature of 160◦F.  Beef products like steaks or roasts can be cooked with 145◦F with a 3 minute rest period.  What is a rest period?  It is the minimum time after you remove the meat product from the heat source (oven, grill, broiler, etc.) before you can eat the product.  Also, temperature is best verified using an instant-read thermometer.

One might wonder why there are 2 different recommended cooking temperatures.  Whole muscle cuts like steaks and roasts are sterile on the inside.  Cooking the products destroys any bacteria present on the outside of these cuts.  However, when meat is ground, any external bacteria that may be present are distributed throughout the ground product. That is why it is so important to ensure that ground products are thoroughly cooked to 160◦F.

Consumers with questions about food safety should contact the USDA’s Meat and Poultry Hotline at 1-888-674-6854.

Helpful links

Third-party experts

Michael Doyle, Ph.D.
Center for Food Safety
University of Georgia
(770) 228-7284

John Sofos, Ph.D.
Department of Animal Sciences
Colorado State University
(970) 491-7703