Do you remember when your food falls on the floor and everyone says that it’s still good to eat it as long as you pick it up within 5 seconds?
Turns out, it’s not completely safe.
In a study published in Applied and Environmental Microbiology
, Professor and Extension Specialist in Food Science, Donald Schaffner, found out that moisture, contact time, and the type of surface contribute to cross-contamination. There are instances that the transfer begins in even less than a second.
Schaffner said, “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. 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.”
In the study
which had 128 different scenarios (different surface type, food type, contact time, and bacterial prep), they found out that watermelon had the most contamination while the gummy candy had the least.
"Transfer of bacteria from surfaces to food appears to be affected most by moisture. 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," Schaffner said.
They also found out that a carpet has very low transfer rates compared to stainless steel or tiles. "The topography of the surface and food seem to play an important role in bacterial transfer," Schaffner said.
While the researchers may prove
that the 5-second-rule may be true in a sense when it comes to contact time, the transfer is also dependent with the nature of food and the surface type of where the food fell in.
"The five-second rule is a significant oversimplification of what actually happens when bacteria transfer from a surface to food. Bacteria can contaminate instantaneously," Schaffner explained.