StoryImage( ‘/Images/Story//Auto-img-11678490013243.jpg’, ‘Photo courtesy of www.uni.heidelberg.de’, ‘E. coli (Escherichia coli) is one of several types of bacteria that normally inhabit the intestines of humans and animals (commensal organism). Some strains of E. coli are capable of causing disease under certain conditions when the immune system is compromised, or disease may result from an environmental exposure. (Definition courtesy of www.answers.com)‘);
No one weapon in the food-safety arsenal will take out E. coli, which is becoming far too familiar to Americans, say University of Illinois scientists Scott Martin and Hao Feng.
However, scientists stay busy every day working on different ways to fight the potentially deadly pathogen. Food science professors work with ozone, high-intensity ultrasound, electrolyzed water, irradiation, and temperature, and they say no treatment singlehandedly can reduce the number of pathogens sufficiently to meet the standards set by the FDA.
We dont believe theres any one technique out there thats going to be effective, said Martin. Were constantly trying different combinations to achieve the 5-log (99.999 percent) reduction in the number of organisms required by the FDA, he said.
Obviously, maintaining quality is a real challenge because if you do anything very harsh to something like spinach or lettuce, the product wont be acceptable, even if its pathogen-free, Martin said.
Both scientists believe theyre getting closer to a solution. With ultrasound, we can actually damage the pathogens cells to the point that they cant be repaired. Ultrasound is a complicated technology, and were still trying to learn how to use it effectively. But this technology causes physical damageruptures in the pathogens cellsand thats important, said Feng.
In Martins lab, a graduate student has eliminated all Listeria monocytogenes on a stainless steel chip in 30 seconds, using a combination of ultrasound and ozone. This extremely positive result has promising implications for the sanitation of processing equipment, the scientist said.
And Martin said the scientists have reduced the length of time it takes to reach the FDAs 5-log reduction standard to 30 seconds, which may still be too long for industry. The thing is, were making steady progress, he said.
And the work goes on. Fengs use of ultrasound, irradiation, and acidic electrolyzed water to eliminate E. coli on alfalfa and broccoli seeds and his use of high-intensity ultrasound to eliminate E. coli in apple cider were published in the February and June 2006 issues of the Journal of Food Science.
Their work on inactivation of E. coli 0157:H7 with peroxyacetic acid, acidic electrolyzed water, and chlorine on cantaloupes and fresh-cut apples was published in the November 2006 article of the Journal of Food Safety.
Weve shown that we have some effective weapons to use against the pathogens that have been in the news so often lately, Martin said. But weve seen the best results when weve combined the various technologies.
Other co-authors on the papers published in the Journal of Food Science and the Journal of Food Safety are Edgar Ugarte-Romero, Keith R. Cadwallader, Scott J. Robinson, Hyun Jung Kim, Mosbah M. Kushad, and Hua Wang, all of the University of Illinois at Urbana-Champaign, Xuetong Fan of the USDAs Eastern Regional Research Center, and Yaguang Luo of the USDAs Produce Quality and Safety Laboratory in Beltsville, Md.
The work was funded by the Illinois Council on Food and Agricultural Research (C-FAR) and the Illinois Agricultural Experiment Station.
From the Jan. 3-9, 2007, issue