Can a Microwave Oven Really Disinfect Your Dirty Sponges?

Let’s start with this: kitchen sponges are just disgusting. A 2017 study published in’s Scientific Reports found that used kitchen sponges contain a whopping 362 different types of bacteria with a staggering 45 billion microbes per square centimeter . According to the report, there are more germs in the kitchen than in the toilet, “mainly due to the use of kitchen sponges, which have been proven to represent the largest reservoirs of active bacteria in the entire home.” More than toilets? Ouch.

So, what can you do to limit the spread of these harmful bacteria all over our dishes and kitchen countertops – other than throwing out a sponge every week? Some say: microwave them . The idea is not new, and it has faced skepticism. The New York Times reported that while a microwave can kill weak bacteria, “the strongest, most smelling, and potentially pathogenic bacteria will survive.”

But Mikaelin Dukleff, whose research during her Ph.D. in chemistry involved growing, studying, and killing bacteria, was not convinced. Dukleff wrote for NPR that the most worrying bacteria in sponges, foodborne pathogens, are “wimps” who once get a little hot, “literally burst.”

Even the authors of the sponge study themselves stated, “Disinfection by boiling or microwaving has been shown to significantly reduce the bacterial load on kitchen sponges and therefore can be considered a reasonable hygiene measure.” But then they said in the next sentence, “However, our data showed that regularly disinfected sponges (as indicated by their users) do not contain less bacteria than uncleaned ones.” HM?

After diving deep into the initial sponges research, food microbiologist Jennifer Quinlan told NPR that “there was no clear explanation of what ‘regular brushing’ means” and that “the study said the sponges were either microwaved or placed in a hot soapy water. … “The latter method, according to Quinlan,” can actually help bacteria grow. ” (Did we mention that there were only five sponges in the study that people reported they were “regularly brushing” in Germany?)

Enter USDA. Microwave and kitchen sponges kill 99.9% of bacteria, according to the USDA . (Test sponges were soaked in nothing other than ground beef juice. Phew.)

So who’s right? While microwaving sponges is not a reliable and long-term solution, it can definitely kill a lot of harmful bacteria and extend the life of your sponge. So basically? Don’t do this forever. Remember that the sponge will still contain some bacteria after nuclear processing and will eventually need to be thrown away. When exactly depends on your tolerance for invisible germs.

How to warm up a sponge in the microwave:

1) Make sure there is no metal cleaning cloth on it. They should be washed in a dishwasher over high heat, including a hot dry cycle.

2) Wet it completely. Dry sponges can catch fire in the microwave.

3) Turn it on at full power for one minute.

4) Let it cool in the microwave for five to ten minutes before taking it out.

A few more tips for the health of sponges: do not use them to clean the juice of raw meat; use a paper towel instead. Clean them regularly (every few days or once a week). And don’t wait too long before throwing them away. A good rule of thumb is about once a month.


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