Truth behind the ‘five-second rule’ when food finds the floor

We all know children drop (or throw) everything on the floor, especially food. As parents, we accept most of that fallen food is destined for the bin, but there are times when we pull out the old five-second rule, dust off that sandwich or bit of fruit and put it right back on the plate.

Bacteria are no match for our super-speed pick-up skills, right? Wrong.

A new study has found the transfer of bacteria from the floor to food happens even after just one second, and sometimes contamination is instant.

Food scientists Robyn Miranda and Donald Schaffner, coated four surfaces – stainless steel, tile, wood and carpet – with bacteria before dropping food on each.

They examined the food at various time intervals – one, five, 30 and 300 seconds – and found, while more time resulted in more bacteria on the food, there was always some contamination.

“Our data clearly showed that contact time does influence bacterial transfer, with more bacteria transferred at longer times,” Robyn and Donald state in their Applied and Environmental Microbiology report, according to ars Technica.

By comparing the food they tested – watermelon, plain bread, buttered bread and Haribo-brand gummy candy – they also found the more moisture a food had, the more bacteria it picked up.

The food scientists found the type of food and the type of surface play a greater role in the amount of contamination on fallen food than time of contact. So gummy lollies are less likely to pick up germs than watermelon.

But, it can take less than a second for bacteria to climb on board fallen food, completely debunking the five second rule.

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