The researchers' poster "Reduction of Escherichia coli O157:H7 in Ground Meat by Selected Spices" reported the antimicrobial effects of 24 spices tested against the foodborne pathogen in a laboratory medium, uncooked hamburger, and uncooked salami. KSU researchers included Erdogan Ceylan, M.S., Donghyun Kang, Ph.D., and Daniel Y.C. Fung, Ph.D.

In the hamburger study, "clove had the highest inhibitory effect, [followed] in potency by cinnamon, garlic, oregano, and sage," Fung said. However, in the laboratory studies, garlic had the highest inhibitory effect.

The addition of 1.0 percent spice (garlic, clove, and cinnamon) to salami mixed with starter culture and E. coli O157:H7 resulted in successful salami fermentation and slight reduction of the pathogen. However, the addition of 7.5 percent garlic and clove killed 99 percent of the pathogen and still resulted in successful salami fermentation.

Though finding the right balance between antimicrobial effectiveness and taste was a challenge, the KSU study showed that clove, cinnamon, and garlic may have the potential to be used in meat products, especially in fermented ones, to control the growth of E. coli O157:H7. Fung said his research may be also applied to other pathogens because often when E. coli is killed, Salmonella and other bad bugs are also destroyed.

"If you add more spice to your cooking, you will definitely knock off more microorganisms, especially if you [season with the spices] that we said kill E. coli," Fung said. "For food manufacturers, similarly, if they use more spice in their products, they will kill more microorganisms."

However, KSU's research has not yet determined whether the amounts of spice that are effective against pathogens are practical for consumers to use in cooking or for food manufacturers to create good-tasting products. Moreover, regardless of how much spice consumers put in their food, they should always use safe food handling practices, including cooking ground beef to an internal temperature of 160 F or until its juices run clear. Only thorough cooking and irradiation can eliminate E. coli O157:H7.

Though spices may be able to reduce E. coli O157:H7 in meat, they do not appear to be able to eliminate it, which underscores the importance of proper cooking. Eliminating E. coli O157:H7 is the only way to eliminate risk of infection since the pathogen has an unusually low infectious dose. In people with compromised immune systems, for example, fewer than 10 cells may cause illness. Spices, however, may potentially add another margin of safety to proper food handling and cooking.

The antimicrobial properties of spices have been noted in several studies, including one published by Cornell University researchers in The Quarterly Review of Biology in March 1998.

The next step in KSU's research is to test the effect of variables, such as cooking, on the antimicrobial power of spices in specific meats.

Daniel Y.C. Fung, Ph.D, is Professor of Food Science in the Department of Animal Sciences and Industry at Kansas State University. Donghyun Kang, Ph.D., is a post-doctorate research assistant and Erdogan Ceylan, M.S., a doctorate candidate.

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