Posted: Wed Jan 24, 2007 11:22 am Post subject: Microwave those Kitchen Sponges.
Scientists have discovered a new weapon against the germs which cause food poisoning - the microwave oven.
Microwaving kitchen sponges for just two minutes can kill 99% of living pathogens, a study in the Journal of Environmental Health claims.
Heat rather than radiation is responsible for the sterilising action on the sponges, say the US researchers.
Around 1.3 million people a year in England and Wales are estimated to suffer from food poisoning.
Sponges and dishcloths are a common source of pathogens which cause food poisoning because the bacteria and viruses, which come from uncooked eggs, meat and vegetables, thrive in the damp conditions.
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
It has been estimated that a kitchen sponge may contain 10,000 bacteria, including E. coli and salmonella, per square inch.
Professor Gabriel Bitton, a expert in environmental engineering at the University of Florida, and colleagues contaminated kitchen sponges and plastic scrubbing pads in dirty water which contained faecal bacteria, viruses, protozoan parasites and bacterial spores.
They then zapped the cleaning equipment in a microwave for varying lengths of time.
After two minutes on full power, 99% of bacteria were inactivated.
And E. coli bacteria were killed after just 30 seconds.
Bacillus cereus spores - which are largely associated with vegetables or foods in contact with soil and are normally quite resistant to radiation, heat and toxic chemicals - were completely eradicated after four minutes in the microwave.
Heat
Professor Britton said it likely to be heat, rather than radiation, that proved fatal as microwaves work by exciting water molecules.
He recommended microwaving damp not dry sponges to minimise the risk of fire and to only microwave non-metal scrubbing pads.
Two minutes every other day would be sufficient for people who cook regularly, he said.
"Basically what we find is that we could knock out most bacteria in two minutes.
"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," he said.
The team also looked at whether the microwave oven could be used to sterilise contaminated syringes.
It was found to be an effective method but took far longer - up to 12 minutes for the Bacillus cereus spores.
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