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Researchers Uncover Methods to Eliminate Listeria Bacteria It's time to remind anyone you know who eats hot dogs cold right out of the package that he or she is courting trouble. Researchers at Kansas State University's Food Science Institute have found an effective way of reheating hot dogs that eliminates any harmful bacteria that might be present.
Listeria causes 2,500 serious illnesses and 500 deaths each year. It primarily affects pregnant women, older adults and persons with weakened immune systems, according to a USDA news release. K-State graduate student Teresa Ortega carried out the microwave experiments between July 2001 and June 2002. Kastner said this experiment is a unique approach to elimination of Listeria on hot dogs. Ortega took packaged hot dogs purchased at a grocery store and put Listeria on the hotdogs in her laboratory to assess which reheating process most effectively kills the bacteria. "Listeria is around us -- it can get on the food product when it is exposed to the environment," Kastner said. Ortega compared the Listeria reductions of seven different ways to reheat a hot dog, including such common cooking practices as boiling in water for 30 seconds or 60 seconds; cooking in an electric oven for 2 minutes or 5 minutes; and microwaving it by itself for 60 seconds or in water for 60 seconds. Ortega found that microwaving a hot dog for 60 seconds wrapped in a paper towel is the most effective way of eliminating Listeria of the seven ways she tested. "Microwave heating causes the product to get hot , and then it begins to emit steam. If you wrap something around the food, steam that comes off is concentrated right at the surface, and you get an additional effect," Kastner explained. Heating hot dogs to kill any bacteria that could be on the surface is safer than eating hot dogs right out of the package, he said. Hot dog manufacturers may be using a process like steam-pasteurization after packaging to kill possible Listeria on hot dogs, Kastner said, and you can do the same thing at home. "You don't have to have Oscar Mayer run the package through steam-pasteurizer -- they might want to -- but then, when you've got the food home, you can take it and heat it in hot water or in the microwave to kill any remaining bacteria yourself," he said. The USDA funded K-State's hot dog research. The USDA Food Safety and Inspection Service has issued a "zero tolerance" policy for Listeria monocytogenes in ready-to-eat meats, including hotdogs, and in poultry products. Results of the K-State study could be used in the future on product labels to advise consumers how to best reheat the products to eliminate possible surface bacteria. Kastner said the research results would be disseminated through the K-State Research and Extension service. Other researchers on the project have been Harshavardhan Thippareddi, now at the University of Nebraska, and Randall Phebus and James Marsden both in the Department of Animal Sciences and Industry and also faculty members in the K-State's Food Science Institute.
Prepared by Tristan Hinderliter
Source: Dr. Curtis Kastner, ckastner@ksu.edu
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