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Food on the floor ‘5 second rule’ debunked

By Agencies - Sep 11,2016 - Last updated at Sep 11,2016

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It might be time to reconsider the “five-second rule” when thinking about eating food that has fallen on the floor.

Researchers at Rutgers University in New Jersey say in a new study that bacteria can contaminate food that falls on the floor instantaneously.

The findings were published this month in the American Society for Microbiology’s journal.

Researcher Donald Schaffner said the five-second rule is a “significant oversimplification of what actually happens when bacteria transfer from a surface to food”.

“The popular notion of the ‘five-second rule’ is that food dropped on the floor, if picked up quickly, is safe to eat because bacteria need time to transfer,” Schaffner said.

“We decided to look into this because the practice is so widespread. The topic might appear ‘light,’ but we wanted our results backed by solid science,” he added.

Schaffner’s research isn’t the first to conclude that the favourite excuse for why that yummy snack that fell on the ground is still OK to eat is wrong.

The research did find that longer contact time means more bacterial transfer, but that the type of food and surface is just as, or more, important.

The Rutgers researchers tested watermelon, bread, bread and butter, and gummy candy on stainless steel, ceramic tile, wood and carpet.

Researchers found that watermelon garnered the most contamination, while gummy candy had the least, and also noticed that carpet had very low contamination transfer rates compared to tile and stainless steel.


“Transfer of bacteria from surfaces to food appears to be affected most by moisture,” Schaffner said. “Bacteria don’t have legs, they move with the moisture, and the wetter the food, the higher the risk of transfer. Also, longer food contact times usually result in the transfer of more bacteria from each surface to food.”

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