Did Myth Busters Get The 5-Second Rule Right?
Learn something about food and safe eating while checking out to see if the Myth Busters really got the 5-second rule right.
We all know this rule and have shared it with our younger siblings: Drop it. Pick it up. And eat it…as long as that item of food has been on the floor for 5 seconds or less. But does this really make any sense? Does it take bacteria over 5 seconds to make its way to a food item that has dropped on the floor?
According to a Rutgers University news release, scientists Robyn C. Miranda and Donald W. Schaffner decided to put this popular urban myth to the test by actually applying some scientific method to whether or not there is any truth to the 5-second rule.
“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,” states Donald Schaffner professor and extension specialist in food science, adding that research involving this rule in peer-reviewed journals is limited.
“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,” said Schaffner, who conducted the research with Robyn Miranda, a graduate student in his laboratory at the School of Environmental and Biological Sciences, Rutgers University-New Brunswick.
Basically the experiment went as follows:
• Four different surfaces (stainless steel, ceramic tile, wood and carpet) were used and applied with two different bacterial growth medias contaminated with a nonpathogenic “cousin” of Salmonella bacteria.
• To each of the surfaces, four different food items (watermelon, bread, bread and butter, and gummy candy) were applied on each type of surface for the time periods of less than one second, five seconds, 30 seconds and 300 seconds.
• Afterward, samples were analyzed for the presence and amount of bacteria.
What the researchers found was that bacteria can transfer essentially immediately on contact with food that is dropped. Furthermore, the wetter the food the more likely it is to be contaminated― watermelon had the most contamination, gummy candy the least.
“Transfer of bacteria from surfaces to food appears to be affected most by moisture,” said Professor Schaffner. “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.”
According to the news release, one unexpected finding was that “…carpet has very low transfer rates compared with those of tile and stainless steel, whereas transfer from wood is more variable. ‘The topography of the surface and food seem to play an important role in bacterial transfer,’ Schaffner said.”
The researchers concluded that while the five-second rule is “real” in the sense that longer contact time results in more bacterial transfer―it’s better to be quicker than slower if you intend to go ahead and eat the dropped item―it also shows that other factors are to be considered such as the nature of the food and the surface it falls on, are of equal or greater importance.
For more about food safety, here’s one that includes the 2-hour rule.
Rutgers University―”Rutgers Researchers Debunk ‘Five-Second Rule’: Eating Food off the Floor Isn’t Safe”
“Longer Contact Times Increase Cross-Contamination of Enterobacter aerogenesfrom Surfaces to Food” Applied and Environmental Microbiology, 2016 Vol. 82, Issue 18; Robyn C. Miranda, Donald W. Schaffner.
Discovery.com: MythBusters “Five-Second Rule MiniMyth”
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