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Extracts from plants such oregano were active against several foodborne pathogens, including E. coli O157:H7, Listeria monocytogenes, and Salmonella enterica, in ARS tests. Photo courtesy of McCormick & Company, Inc.

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Spice-Rack Favorites Battle E. coli and Other Foodborne Pathogens

By Marcia Wood
July 14, 2008

Herbs and spices like oregano, thyme, cinnamon and clove do more than add pleasing flavors and aromas to familiar foods. The oils from these plants, or compounds extracted from those oils, pack a powerful, antimicrobial punch—strong enough to help quell such foodborne pathogens as Escherichia coli O157:H7.

That's according to Agricultural Research Service (ARS) chemist Mendel Friedman, who several years ago evaluated the bacteria-bashing power of these and dozens of other plant compounds.

Now, some of the compounds that Friedman and co-investigators determined were the strongest combatants of E. coli, Salmonella enterica, Campylobacter jejuni, or Listeria monocytogenes in the 2002 study are being tapped for new research focused on food safety.

For example, Friedman, research leader Tara H. McHugh, and other scientists at the ARS Western Regional Research Center in Albany, Calif., are evaluating the highest-ranking botanical bactericides as potential ingredients in what are known as edible films.

A thin, pliable, edible film for the future might be made of puréed spinach spiked with carvacrol, the compound responsible for oregano's ranking as a top fighter of E. coli in the Friedman study.

The scientists want to find out whether adding small squares of carvacrol-enhanced spinach purée film to bags of chilled, ready-to-eat spinach leaves would help protect this salad green against E. coli.

Friedman is also exploring other new uses of the top-rated botanicals from the earlier study. That investigation, which he conducted with technician Philip R. Henika and research leader Robert E. Mandrell at Albany, was the most extensive of its kind at the time it was published. Also notable was the common basis of comparison, which the team established by inventing new methods to prepare and test all of the samples. For even more consistency, the scientists used the same bacterial strains—from the same suppliers—throughout the investigation.

Read more about the research in the July 2008 issue of Agricultural Research magazine.

ARS is a scientific research agency of the U.S. Department of Agriculture.