How long can you leave dropped food before it’s unsafe to eat it?
Search Google for restaurants named “Genghis Khan” and you’ll find over 7,000.
It’s clearly a popular choice for restaurateurs.
And I’m 100% certain the food hygiene standards of each and every one are far removed from the man himself.
You’ve probably come across the “Five-Second Rule,” a kind of working hypothesis that supposedly tells you whether it’s safe to eat an item of food you’ve dropped on the floor.
More on this in a minute.
But first, legend has it that the idea of there being any kind of time limit for dropped food goes all the way back to that 13th century Mongolian ruler, yup Genghis Khan himself, known of course as an utterly ruthless dictator.
And apparently a bit free and easy with his food handling procedures.
You see, some report he was okay with food remaining on the floor for twelve hours—or even twenty—after it had tumbled onto the tundra.
Others go even further, suggesting that food could be safely picked up and eaten after any period Khan allowed.
The principle was that all food worthy enough to be prepared for Khan would be worthy enough to eat, no matter how long it had been on the ground.
These days it’s more likely that you’ll have come across the Five-Second Rule. It was even in the news this very month after being the subject of a rigorous study conducted by Rutgers University in New Jersey, published in the American Society for Microbiology’s journal.
Research leader Professor Donald Schaffner said that although longer contact times can result in more bacteria transferring, the truth is that pathogenic bacteria can change places in the blink of an eye.
No wonder Professor Paul Dawson of Clemson University in South Carolina has previously said he compares picking up dropped food and eating it to not wearing a seatbelt.
The Rutgers researchers meticulously dropped watermelon, bread (buttered and unbuttered), and gummy candy (Haribo’s strawberry to be precise) from a height of 5 inches onto four different surfaces that had been disinfected, inoculated with Enterobacter aerogenes, then allowed to dry. The surfaces were stainless steel, ceramic tile, wood, and carpet.
Contact time ranged from less than one second to a full five minutes.
Watermelon picked up the most contaminating bacteria, while the gummy candy acquired the least.
The highest transfer rates came from stainless steel and tile—the lowest from carpet. Transfer rates from wood were variable.
Actually, the “fact” that the Five-Second Rule is simply an urban myth has already been demonstrated through a whole string of scientific experiments by others.
For example, a high school student, Jillian Clarke, who was doing a six-week internship at the University of Illinois was actually awarded a 2004 Ig Nobel Prize for debunking the rule.
Then in 2005, the TV show MythBusters looked into it by comparing bacterial colonies picked up by dry saltines and wet pastrami.
As their website delicately puts it, “moist sausage scooped up the most flora.”
Then, in a 2014 British study led by Professor of Microbiology at Aston University, Anthony Hilton, students found similar results to the Rutgers team, concluding that the greatest transfer of contamination occurs when moist foods hit smooth surfaces.
The British team also conducted a survey which showed that 87% of people said they would eat food dropped on the floor, or already had.
They also found that 81% of females adopt the Five-Second Rule, while only 64% of males do, men presumably tending to come more from the Genghis Khan school of hygiene.
So where did this Five-Second Rule originally come from?
Well, beyond discovering that Genghis Khan had his Twelve-Hour Rule, or his Twenty-Hour Rule, or his As-Long-As-I-Damn-Well-Say Rule, we weren’t able to pin it down precisely.
We do, however, definitely know that sixteen years ago it was a sufficiently well-established idea to play the central part in a Volkswagen Passat TV commercial, called “Five-Second Rule,” in which a new father says: “Suddenly I’m the one saying ‘Don’t touch the cookie on the ground’ when I’m really thinking ‘Five-second rule.’”
Prior to that, we found mentions of a Five-Second Rule for working out how far back you should drive from the car ahead of you, and another used in the game of croquet, believe it or not.
However for the last word, let’s pay close attention to Dr Roy Kulik, who heads the serious-sounding division of infectious diseases at Weill Cornell Medical School.
He warns that eating dropped food poses a risk of gastrointestinal disease.
“The five-second rule,” he says, “probably should become the zero-second rule.”