Who is more likely to eat food after falling to the floor? Probably not, a new study says.
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The “five-second rule” has always been a scientific truth universally accepted by people all over the world whose expectations at biting into something delicious have just been quashed by Newtonian forces of evil.
They tested watermelon, bread, butter and gummy sweets on four surfaces – stainless steel, ceramic tiles, wood and carpet.
The five-second rule is ubiquitous: Adults and children, slovenly and squeaky-clean people alike, often scoop food off the floor after it drops and, as long as it has been less than five seconds, eat it without second thought.
The scientists then contaminated each of these surfaces with a salmonella-like bacteria known as Enterobacter aerogenes for various lengths of time.
Researchers said the five-second rule is a “significant oversimplification of what actually happens when bacteria transfer from a surface to food”.
And that doesn’t even get into the trickier rules, such as the well-known Guest Addendum, which provides you with 15 to 20 seconds of immunity so long as you’ll just eat that one – it’s fine, look, see, fine. Does it take bacteria over 5 seconds to make its way to a food item that has dropped on the floor?
Although time was a factor – broadly speaking, the longer a food touched a surface the more bacteria it had – what was far more relevant was the composition of food or surface.
Watermelon picked up the most contamination on all surfaces, because the more wet a food is, the easier it is for bacteria to exist on it. Surfaces that are more flat, such as tile and stainless steel, also had much higher rates of bacterial transfer than carpet or even wood, which has a variable surface.
The Rutgers researchers dropped watermelon cubes, Haribo strawberry gummies, plain white bread and buttered bread (purchased from a New Jersey ShopRite) onto various surfaces from a height of about five inches. Gummy candy had the least amount of bacteria, suggesting germs more easily transfer to wet or moist foods, the study authors said.
“Bacteria don’t have legs, they move with the moisture”, as Schaffner pointed out.
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The findings were published this month in the American Society for Microbiology’s journal.
