Your microwave or dishwasher can make sponges safer to reuse in today's kitchens.
Heating your used kitchen sponges in your microwave for one minute, or washing them in your dishwasher and leaving them there through a drying cycle, are the most effective household ways to inactivate harmful bacteria, yeasts and molds.
ARS food safety experts who specialize in research on foodborne pathogens, like E. coli O157:H7, looked at several simple, convenient and often-recommended ways of cleaning reusable kitchen sponges. Techniques included soaking sponges for three minutes in a 10-percent chlorine bleach solution, soaking in lemon juice or sterile water for one minute, heating in a microwave at full power for one minute, or washing in a dishwasher—including through a drying cycle.
At the outset of the experiment, they soaked all the sponges for 48 hours at room temperature in a slurry of ground beef and laboratory compounds which allow bacteria, yeasts and molds naturally present in the beef to grow on the sponges.
Microwaving and dishwashing each killed nearly 100 percent of the bacteria, with dishwashing being only slightly (0.0001 percent) less effective.
And, microwaving and dishwashing each killed nearly all yeasts and molds; less than 1 percent (only 0.00001 percent) survived.
For details contact Manan Sharma or Cheryl L. Mudd, (301) 504-8400; USDA-ARS Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Md.