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Do bacteria only adhere to dropped food after 5 seconds?
Some people react extremely quickly when food falls out of their hands and onto the floor. After all, there is the “5-second rule”, according to which it takes some time for food that has fallen down to become contaminated with bacteria. But what is the point of this rule?
Does it always take five seconds before contamination?
What to do if the pizza slice you just bought or the roll you just placed falls on the floor? Pick up and throw away or eat anyway? Some people think that it is safe to eat dropped food as long as it is picked up quickly enough.
Finally, there is the so-called “5-second rule”, according to which it takes at least five seconds for bacteria to adhere to it. Researchers from the United States have now found in a study that the process of contamination is somewhat more complicated.
The type of surface and contact time play a role
Scientists Professor Donald Schaffner and Robyn Miranda from Rutgers University in the US state of New Jersey believe that the five-second rule is too generalized.
According to the researchers, who published their results in the journal "Applied and Environmental Microbiology", the moisture of a food, the type of surface and the contact time with the ground play a decisive role for the so-called cross-contamination. According to the experts, the transfer time is sometimes less than a second.
Try different foods
In the course of the study, the scientists applied Enterobacter aerogenes, a harmless bacterium, to four different surfaces: on stainless steel, ceramic tiles, wood and carpet. Then they dropped four different foods - watermelon, gummy bears, bread, and sandwiches.
The respective foodstuffs then remained in place for less than one second, five, 30 and 300 seconds. Each individual combination was repeated 20 times.
Bacteria transfer is affected by moisture
Not surprisingly, as the university wrote in a statement, watermelon was the most contaminated and gummy bears the least. Moisture affects the bacterial transfer the most.
"Bacteria have no legs, they move with the moisture and the wetter the food, the higher the risk of transfer," says Schaffner. It was surprising that the transfer rate for the carpet surface was very low compared to the rate for tiles and stainless steel.
Dropped food doesn't have to be thrown away
"The nature of the surface and the food also seem to play an important role in the transfer," said Schaffner. According to the researchers, the five-second rule is "a gross simplification". "Bacteria can contaminate immediately."
However, this does not have to mean that dropped food has to be thrown away. According to health experts, dirt cleanses our stomach. According to experts, stomach acid is so strong that it kills almost all bacteria. (ad)