28 August 2000
Deadly For Bacteria, Great For Consumers
by Kate Melville
"Electrolyzed water" - produced by applying an electrical current to a very dilute saltwater solution - kills bacteria on fresh produce more effectively in some cases than heat or water containing chlorine, according to a research report presented here today at the 220th national meeting of the American Chemical Society, the world's largest scientific society.
Electrolyzed water could also be used to sanitize cutting boards, eating and drinking utensils, and food-processing equipment, says Yen-Con Hung, Ph.D., the University of Georgia professor who conducted the research. Soaking a cutting board in electrolyzed water for about five minutes at a moderately warm temperature (about 95-105 F) can reduce bacteria up to a million-fold, he says.
One advantage of using electrolyzed water to kill bacteria on food surfaces is that it doesn't adversely affect quality as heat can, according to Hung.
Trained sensory panelists "found there was no significant effect of the treatment on the quality," he said. They were "unable to find any differences in color, appearance or smell" between produce washed with electrolyzed water and produce washed with tap water.
The electrolytic process produces very acidic water. Hung believes the water's low pH (acidity) and potential for oxidation-reduction contribute to its effectiveness. Essentially, oxidation-reduction involves the exchange of electrons. In the case of bacteria like E. coli, salmonella and listeria, this exchange may take away electrons needed by cell membranes for metabolism and survival.
"We think the main indicator of the effectiveness of the solution is the oxidation-reduction potential," says Hung. "When you compare chlorinated water with electrolyzed water, there is a difference in the oxidation-reduction potential, even though they have the same chlorine concentration." The exact role of oxidation-reduction in destroying bacteria is still being investigated, he says.
Chlorine is not physically added to electrolyzed water, but is produced when the electrical current passes through the water and salt mixture. The chlorine that is generated "is definitely one of the major components for killing microorganisms," Hung acknowledges. But, he adds, electrolyzed water has additional active components - oxidants - that his research group is trying to identify.
The equipment needed to produce and treat food with electrolyzed water is compact and already produced by several companies in Japan. A typical unit costs between $3,000 and $5,000, says Hung. He believes the food industry will be first to use electrolyzed water and then, as equipment costs come down, consumers will use it at home.
A fast-food chain in the United States is testing the technology and several other companies have expressed interest, according to Hung. He did not identify them.
A few U.S. water treatment plants already use technology similar to that tested, according to Hung.