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Carcass breaking research could pave way for safer beef

New research points to the beef carcass breaking process as a major source of disease-causing bacteria, not the carcass dressing process, as is often thought to be the case.

The research findings lead Dr. Colin Gill, an Agriculture and Agri-Food Canada researcher in Lacombe, Alta., to believe that redesigned carcass breaking equipment could significantly reduce the levels of E. coli contamination, and therefore result in safer beef.

Gill conducted his research to help the beef industry find ways to reduce the risk of beef being contaminated with pathogenic bacteria in the wake of increased food safety concerns. Safer beef means a more saleable, marketable product, which is good for producers, and it means fewer product recalls, which is good for processing plants and the stores that sell the beef.

E. coli is a common bacterium that lives in the intestines of cattle, but it can be transferred to the surface of beef during processing. Most strains of E. coli are harmless, but some, such as E. coli O157:H7 can cause disease. Usually, proper handling and cooking of beef is the best defence against E. coli infection in humans.

Because beef is pasteurized after the carcass dressing process, very few E. coli-infected carcasses enter the breaking facilities; however that hasn't completely eliminated the E. coli threat. Since E. coli tend to reappear on the meat after carcass breaking, Gill decided to take a closer look at the carcass breaking process - to determine why intestinal bacteria sometimes contaminate meat during carcass breaking.

"Traditionally, efforts to prevent beef contamination have focused on the carcass dressing process or on the cattle before they come for processing," says Gill. "It seemed that further bacterial contamination of meat could occur during carcass breaking. The research results showed the levels of E coli on beef were often higher after carcass breaking than before."

Gill used two beef packing plants for his research. At Plant A, where approximately 120 carcasses are broken per hour, samples were taken after carcass breaking to determine total aerobic counts, coliforms and E. coli. For each group of bacteria, numbers were greater on trimmings than on carcasses entering the breaking process.

"Not only were the numbers greater after breaking, but the numbers of bacteria recovered from the cattle trimmings tended to increase at successive stages of trimmings collection," says Gill.

At Plant B, where 240 carcasses are broken per hour, the microbiological effects of six out of 16 sequential breaking operations (operations 1, 4, 5, 7, 8 and 12 were examined) on random hanging beef carcasses were evaluated. Each carcass tested was swabbed at specific sites before and after six breaking operations.

At five of the six sites swabbed, the operation related to each did not increase the numbers of the few coliforms or E. coli at the site, and in fact, operation 7 (trimming the rump), decreased the numbers of coliforms and E. coli at a site in the anal area. However, samples were also taken from cotton gloves worn by workers involved in the breaking of hanging carcasses and those findings were the opposite.

"For the glove samples, E. coli was recovered in rather large numbers from the water in which gloves were rinsed and in small numbers from swabs of those same gloves," says Gill. "This leads us to believe that the gloves must become contaminated with E. coli from surfaces within the breaking facility, as the numbers are too high to be derived from the carcasses."

Gill says this information points to two sources of contamination. One, fixed carcass breaking equipment, such as conveyors, and two, equipment worn or used by workers, such as steel mesh gloves and knives.

Finding the sources of contamination leads to a need for solutions. Gill suggests that carcass breaking equipment be redesigned to improve cleanability, to assure that the equipment can be wholly cleaned during each working day. A lot of carcass breaking equipment is currently not designed to be cleanable, therefore it cannot be adequately cleaned during routine daily cleaning. In the interim, though, Gill says merely keeping the product and the carcass breaking equipment dry will reduce the risk of contamination.

In the future, Gill suggests that appropriate microbiological sampling be used to determine whether equipment is adequately clean and not the current method, which is largely based on inspection of meat contacting surfaces for visible cleanliness.

CABIDF is a joint $16.4 million fund of Alberta Agriculture, Food and Rural Development and Agriculture and Agri-Food Canada. The Fund is administered by Alberta Beef Producers and has supported more than 50 projects in five major categories identified to benefit the Alberta beef industry.

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