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Enhancing the Heat Sensitivity of Escherichia coli O157:H7 in Ground Beef by Monocaprylin


Ground beef is the most popular beef product consumed in the United States. While E. coli
O157:H7 in ground beef has decreased significantly according to government data, there is still
work to be done to prevent foodborne illness. The U.S. Department of Agriculture recommends
that ground beef patties should be cooked to an internal temperature of 160°F, however
consumers tend to rely more on the color and texture of cooked meat as a means of determining
doneness. Unfortunately, premature browning in ground beef can lead to inadequate cooking by
consumers, which can in turn lead to the survival of E. coli O157:H7. When compared to steaks
and roasts, ground beef is especially problematic because of the accelerated oxidation of
myoglobin that occurs as a result of grinding. The grinding process can also lead to a greater
distribution of pathogenic bacteria. The infectious dose of E. coli O157:H7 is very low—two to
2,000 cells—emphasizing the importance of properly cooking ground beef. An antimicrobial
hurdle applied at the end-user level would be prudent to inactivate E. coli O157:H7 and prevent
foodborne illness. <P>

Caprylic acid is a fatty acid present in breast milk, bovine milk and coconut oil and is a foodgrade chemical approved by the Food and Drug Administration as “generally recognized as safe”
(GRAS). Monocaprylin is a form of caprylic acid. Monoglycerides such as monocaprylin have
been hypothesized to act as non-ionic surfactants, which penetrate and get incorporated into
bacterial plasma membranes, thereby altering membrane permeability thus increasing their
sensitivity to heat. Applying caprylic acid to ground beef might help ensure that consumers cook
it to the appropriate level of doneness.

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Findings: This study was conducted to check if addition of monocaprylin in small amounts to ground beef can kill E. coli O157:H7 in undercooked patties. E. coli O157:H7 was added to ground beef patties with and without monocaprylin, and cooked to internal temperatures of 60oC, 65oC or 68oC. Results showed that addition of monocaprylin killed substantial numbers of E. coli O157:H7 in undercooked patties, compared to patties containing no monocaprylin. Moreover, it was found that addition of monocaprylin did not adversely affect the color of ground beef compared to ground beef with no monocaprylin.

<P> For complete projects details, view the <a href="…; target="_blank">Project Summary. </a>

Faustman, Cameron; Venkitanarayanan, Kumar
University of Connecticut
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