The five-second rule is off by about five seconds in many cases, and not in the direction you hoped.
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“The popular notion of the five-second rule is that food dropped on the floor, but picked up quickly, is safe to eat because bacteria need time to transfer”, Schaffner told Rutgers Today.
A new study from Rutgers University in New Jersey indicated that the five-second rule – one in which and food dropped on the floor is safe to eat within five seconds of picking it up – isn’t actually true.
In 2006, a study found that salmonella was far more long-lived on substances like wood than expected, and that the wetter and broader the food, the more likely for significant contamination.
You may want to think twice the next time you invoke the five-second rule for food that’s fallen on the floor.
Schaffner’s findings appear online in the American Society for Microbiology’s journal, Applied and Environmental Microbiology. The majority follow the five-second rule.
In the recently Researchers in Rutgers’ food science department tested four surfaces (stainless steel, ceramic tile, wood and carpet) and four different foods -(watermelon, bread, bread and butter, and gummy candy).
So, could eating food off the floor be good for you? “The topography of the surface and food seem to play an important role in bacterial transfer”, Schaffner said. Well, even if the “five-second” bit doesn’t have any scientific basis, the data does support the idea that a food becomes more risky the longer it stays on the ground, at least in some cases.
And earlier this year, the Discovery Science Channel aired a segment in which the narrator said that “moist foods left longer than 30 seconds [on the ground] collect 10 times the bacteria than those snapped up after only three”.
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It’s worth keeping in mind that food doesn’t necessarily become unsafe the instant it comes in contact with bacteria, as a certain amount of bacteria needs to transfer over before there’s a serious health risk. More bacteria can get on your food the longer it’s on the floor, but, just like in the previously published study, they found that contamination had already started at initial food-to-floor contact. It also showed that while, yes, the longer a food remains dropped the more bacteria it acquires, it also depends on what kind of food it is and the surface on which it’s been dropped.
