Boffins at the University of Florida (UF) have found that microwaving kitchen sponges and scrubbers - long known to be carriers of the bacteria and viruses that cause food-borne illnesses - sterilizes them rapidly and effectively. "Basically what we find is that we could knock out most bacteria in two minutes," said UF's Gabriel Bitton. "People often put their sponges and scrubbers in the dishwasher, but if they really want to decontaminate them and not just clean them, they should use the microwave."
Bitton's research into microwave sterilization appears in the Journal of Environmental Health, and the findings provide a handy household sterilization strategy for tackling E. coli and other bugs at the root of food poisoning and other illnesses. Home kitchens are a common source of contamination, as pathogens from uncooked eggs, meat and vegetables find their way onto countertops, utensils and cleaning tools. Previous studies have shown that sponges and dishcloths are common carriers of pathogens, in part because they often remain damp, which helps the bugs survive.
Bitton's research involved soaking sponges and scrubbing pads in raw wastewater containing a "witch's brew" of fecal bacteria, viruses, protozoan parasites and bacterial spores, including Bacillus cereus spores. Bacillus cereus spores are resistant to radiation, heat and toxic chemicals, and they are difficult to kill.
Using an off-the-shelf microwave oven to zap the sponges and scrub pads for varying lengths of time, the researchers then determined the microbial load in each sponge and cloth. The results, according to Bitton, were unambiguous. Two minutes of microwaving on full power mode killed or inactivated more than 99 percent of all the living pathogens in the sponges and pads, although the Bacillus cereus spores required four minutes for total inactivation.
The study noted that heat, rather than the microwave radiation, is what proves fatal to the pathogens. And because the microwave works by exciting water molecules, it is better to microwave wet rather than dry sponges or scrub pads. "The microwave is a very powerful and an inexpensive tool for sterilization," Bitton said, adding that people should microwave their sponges according to how often they cook, with every other day being a good rule of thumb.
Source: University of Florida
Pic courtesy UF/Kristen Bartlett