Scientists are throwing cold water on the way we wash dishes.
For years, we used near-boiling water, scrubbing and rinsing to make lipstick and mounds of caked-on food disappear from plates and glasses. We believed that high temperatures would kill any germ. Now those views are headed for the drain.
Research from Ohio State University says stains and bacteria can be removed from plates and glasses in water at room temperatures just as well. Just wash in soapy water, rinse and introduce a dash of dish sanitizer–the ammonia solutions used in restaurants but little-known in households, according to postdoctorate student Jaesung Lee and Melvin Pascall, a professor in food science and technology. Their research will appear in June’s Journal of Food Engineering.
Some restaurant owners prefer washing dishes by hand instead of using dishwashing machines to clean the toughest muck. And health officials already have embraced the cool-water-and-dish-sanitizer concept.
“As long as people wash their dishes in cooler temperatures, rinse and use a sanitizer, it will work,” said Paul DeSario, program manager for food safety at Ohio’s Cuyahoga County Health Department. “Restaurants know about using the sanitizer. But people at home? It may be an extra step that they just aren’t used to.”
Federal officials recommend that restaurant employees who manually wash dishes use water at 110 degrees or more.
But few restaurant workers use water that hot because it is so uncomfortable, the Ohio State researchers say. So Lee and Pascall sought to determine whether cooler water could kill off germs that thrive on plates and glasses in restaurants.
The researchers coated dishes with cheese, eggs, milk and jelly and added hard-to-kill E. coli and Listeria bacteria, which can cause foodborne disease outbreaks.
Hot, soapy water followed by a soak in a dish sanitizer wiped out nearly all microscopic organisms. But cooler water, followed by a rinse and sanitizer, killed off germs just as well, according to the research.
Don’t expect all restaurant owners to embrace the chapped, skin-peeling fingers of their employees and turn down the heat. Several restaurateurs said they would continue to wash dishes in high-temperature water.
“Some detergents won’t work unless the water reaches a certain temperature,” said Brian Hilberg, the owner of Marie’s Cafe, an upscale restaurant in Medina, Ohio. So Hilberg’s employees wash dishes and glasses in hot, soapy water. They rinse the dishes in hot water and sanitize them in hot water.
In fact, Hilberg said, his employees scrub the plates and glasses because he doesn’t think a dishwashing machine can clean the lipstick off glasses or the melted cheese that sits for hours on plates or in pots.
Ohio State’s researchers, incidentally, said lipstick and melted cheese — along with dried milk–were the toughest things to clean.
