By Janet Raloff
Cooking will kill almost any microbe. But when it comes to serving raw foods, such as the vegetables in a garden salad, neutralizing germs with heat is not an option and washing the greens doesn’t reliably disinfect. Although raw produce can be sanitized in a bath of dilute bleach, a team of Georgia scientists is developing an alternative—acidic electrolyzed water—that appears to kill microbes even more effectively and could be just as cheap and easy.
“The technology is not new,” explains Yen-Con Hung of the University of Georgia in Griffin. It relies on an electric current between two electrodes sitting in a solution of brine—the same process used to generate chlorine commercially. The kitchen version of the method differs in that the starting solution is much more dilute, containing a mere 0.1 percent sodium chloride.
With a membrane-based device about half the size of a microwave oven, the researchers separate this dilute salt water into acidic and alkaline fractions. The acidic portion exhibits “strong antiviral and antibacterial properties,” Hung reported last month at the American Chemical Society meeting in Washington, D.C.
In one test, he started with 100 million cells of pathogenic bacteria—either Escherichia coli O157:H7, Salmonella, or Listeria monocytogenes—on a palm-size patch of a plastic cutting board. He then immersed the board in tap water for 5 minutes. When it emerged, it still held 10,000 cells. Another piece of plastic that had started out equally germy but then was dunked in acidic electrolyzed water carried only 100 cells.
“The important thing to realize,” Hung says, “is that most foods or surfaces [in the kitchen] will not start out with such heavy contamination.” When the starting levels are lower, total elimination of the bacteria is possible, he claims.
Hung says that to slay germs, the new technique employs various reactive agents—especially hypochlorous acid—that form from the salt’s chlorine. Water treated with chlorine bleach also sanitizes with hypochlorous acid, but Hung’s data suggest that electrolyzed water outperforms the bleach-based technique and keeps its potency longer.
Hung is now testing the electrolyzed water, which is safe to ingest, for sanitizing egg shells, apples, and lettuce.
