Scientists took a hard look at what happens when food hits the floor. And the results were not pretty.
NEW BRUNSWICK -- The oft-quoted "five-second rule," for the length of time where its safe to eat food that has dropped on the ground, turns out to be just wishful thinking, according to a recent study by Rutgers University.
Donald Schaffner, professor and extension specialist in food science at Rutgers University, found that moisture, type of surface and contact time all contribute to cross-contamination, and, in some instances, the transfer begins in less than one second.
"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."
The study also found some foods to be more of a bacteria-magnet than others -- watermelon pieces had the highest concentration of bacteria of foods tested while gummy bears had the least.
"Bacteria don't have legs, they move with the moisture, and the wetter the food, the higher the risk of transfer," Schaffner said.
While researchers confirmed that the longer amount of time spent on the floor, the more bacteria it will collect, Schaffner said, the findings also show other factors, including the nature of the food and the surface it falls on, are of equal or greater importance.
Among the surfaces tested -- carpet, wood, tile and stainless steel -- carpet was found to have a very low transfer rate compared to tile and stainless steel, and the transfer from wood was found to be more variable.
"The topography of the surface and food seem to play an important role in bacterial transfer," Schaffner said.
Still, he said, regardless of whether you're eating watermelon or gummy bears, contamination is immediate -- so it's still better to just throw it out than to try and eat it.
Schaffner's findings appear online in the American Society for Microbiology's journal, Applied and Environmental Microbiology.
Justin Zaremba may be reached at jzaremba@njadvancemedia.com. Follow him on Twitter @JustinZarembaNJ. Find NJ.com on Facebook.
Photo by Andrew Seaman via Creative Commons.