How to Clean Kitchen Sponges Effectively

Kitchen sponges are useful for everyday cleaning, but they can also collect bacteria, yeasts, and moulds over time. Researchers at the Agricultural Research Service (ARS) Food Technology and Safety Laboratory in Beltsville, Maryland, tested several common kitchen sponge cleaning methods to see which worked best at reducing harmful microbes.

How the Sponge Cleaning Methods Were Tested

Microbiologists Manan Sharma and Cheryl Mudd, together with two student interns, prepared heavily contaminated sponges by soaking them for 48 hours in a mixture of ground beef and laboratory growth medium. Each sponge contained around 20 million microbes before testing began.

The researchers then compared five different kitchen sponge sanitising methods. The sponges were either soaked in a 10 percent chlorine bleach solution for three minutes, soaked in lemon juice or deionised water for one minute, microwaved for one minute, placed in a dishwasher with a drying cycle, or left untreated.

Which Method Worked Best?

The results showed a clear difference between the cleaning methods. Bleach, lemon juice, deionised water, and leaving the sponges untreated reduced bacteria by between 37 and 87 percent. However, enough bacteria remained to potentially cause illness.

Microwave heating and dishwashing produced much stronger results. Microwaving reduced bacteria by 99.99999 percent, while washing the sponge in a dishwasher with a drying cycle reduced bacteria by 99.9998 percent.

What About Yeasts and Moulds?

The researchers found similar results for yeasts and moulds. Sponges treated in the microwave or dishwasher retained less than 1 percent, while between 6.7 and 63 percent survived after the other treatments.

Takeaway

In this study, microwave heating and dishwashing with a drying cycle were the most effective methods tested for reducing bacteria, yeasts, and moulds in kitchen sponges. Keeping reusable sponges properly cleaned can support better kitchen hygiene and food safety and may help reduce the spread of microbes around food preparation areas.

Safety note: Always follow appliance and sponge manufacturer instructions. Do not microwave sponges containing metal and never microwave a dry sponge.

Reference

Read Further

Best Ways to Clean Kitchen Sponges. (2007). Journal of Environmental Health, 70(2), 57