Show of hands, how many of you are guilty of quickly picking up your food from the floor and eating it because of the “5-second rule”?
Rutgers researchers have debunked the widely accepted notion that it's safe to eat food within the "safe" five-second window.
In a study, Donald Schaffner, a professor and extension specialist in food science, found that several factors contribute to cross-contamination, including moisture, type of surface and contact time. In some instances, the transfer begins in less than a second.
Four different surfaces as well as different foods were tested. Researchers tested on stainless steel, ceramic tile, wood and carpet. For the foods, they took a look at watermelon, bread, bread and butter and gummy candy.
While the surfaces and foods are important factors, researchers also had to consider different contact times (to check if the five second rule had some truth to it or if it was absolute garbage).
They tested less than one second, five seconds, 30 seconds and 300 seconds (or as most of us would say, five minutes).
They also grew Enterobacter aerogenes, a nonpathogenic "cousin" of Salmonella that is naturally occurring in the human digestive system. (Simply put, they grew bacteria that is incapable of causing disease in a bid to test our ’five second’ rule theory. Science for the win.)
Watermelon had the most contamination and gummy candy the least. This isn’t to say that you can pick up your gummy candy after it fell on the floor but from this, researchers found that the transfer of bacteria from surfaces to food appears to be affected most by moisture.
In other words, the wetter the food, the higher the risk of transfer. They also noted that longer food contact times usually result in the transfer of more bacteria from each surface to food.
In terms of surfaces, the carpet has very low transfer rates compared with those of tile and stainless steel.
So is the five-second rule real? The research shows that the ’rule’ is "real" in the sense that longer contact time results in more bacterial transfer.
But you also need to account for other factors, such as the nature of the food (the wetness or dryness of the food) and the surface it falls on. However, you are much better off not picking your food up from the floor as contamination may be instantaneous.
"The five-second rule is a significant oversimplification of what actually happens when bacteria transfer from a surface to food," Schaffner said. "Bacteria can contaminate instantaneously."
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