Stemming back all the way to the infamous Genghis Kahn, then jumping to the 1960s with Julia Child, the ‘5-second rule’ has been a cultural phenomenon, sparking debates in many kitchens. According to the so-called ‘5-second rule’, eating food after it’s been dropped on the floor is safe, as long as you do so within five seconds. But is it true? Here’s what scientists have found out, and what you should know.
Why do we trust the rule so much?
We’ve all been there, right? You’re busy prepping the cheese board for tonight’s boardgames, snacking as you go along and sharing stories with friends, until one simple slip of the hand has that last piece of cheese drop to the floor. Or, you’ve just plated your masterpiece of a dessert and as you’re carrying it out to show your family on the stoep, you trip and half of it tumbles to the ground. As you come to terms of what’s just happened, you hear a friend or aunt shout, “It’s alright, it’s only been a second”, or “Quick! 5-Second rule!”.
These events have been happening for much longer than we would think, and justifying eating fallen or dropped food with the rule mostly stems from long ago. One story has been traced as far back as Genghis Kahn, founder of the Mongol Empire. Allegedly, Kahn created the “Kahn Rule” at his banquets, where if food dropped onto the floor, it could stay there for as long as he deemed fit.
Another story, several centuries later, has chef and television personality Julia Child further contributing to the myth. On one of her The French Chef episodes in the 1960s, Child flipped a pancake only to have it flop out of the pan and onto the stovetop. She quickly returned it to the pan, stating that you can always pick it up if you’re alone in the kitchen.
Although the origin of the magic number five is yet to be discovered, what these stories do shed light on is how people may have learned to handle dropped food. The question still stands: does five seconds actually make a difference when it comes to food safety and the risk of germs?
Lab-tested: The 5-second rule
Let’s get straight to it: there’s no truth to the five-second rule. According to a research study performed by Paul Dawson, PhD, a professor at Clemson University, when food is dropped and it falls to the floor (actually any surface for that matter), its level of contamination is maily determined by the “dirtiness” of the floor rather than the length of time it’s been on the surface. Plainly put, food that falls on a germ-ridden floor will definitely pick up germs, regardless of how long it stays there.
Professor Dawson even went as far as testing the rule in the lab. He and his team contaminated a few surfaces with Salmonella bacteria (wood, tile, and carpet), one of the most common causes of food poisoning. The team then followed up by dropping bologna (a moist food) and white bread (a dry food) onto each of the surfaces multiple times. Each food was left for five, 30 and 60 seconds respectively.
The samples were measured for bacteria for each time frame. According to the team, high levels of Salmonella were found on both the moist and dry food, regardless of the contact time and surface. While there were some differences, there was still an alarming amount of cross-contamination across the board.
Their conclusion is clear: if food drops onto a surface, it will pick up any germs present from said surface.
What to do instead
Although a myth, the ‘5-second rule’ doesn’t necessarily mean that all fallen foods are unsafe. The health risk depends on quite a few factors:
- Amount and type of bacteria/microorganisms: Has the surface been cleaned thoroughly? Is it indoors or outdoors? Is the surface wet, dry, or porous? Diffrerent environments can make some microorganisms/bacteria flourish more than others.
- Type of food dropped: It is possible to remove some of the bacteria by washing foods, like raw fruits and vegetables. However, not all foods can be washed, like crackers, roast chicken or white bread, for example.
- Overall health status of person/s eating the food: In general, the stronger a persons immune system, the lower the risk of food poisoning, and the weaker or more compromised a persons immune system, the higher the risk of food poisoning.
So, the next time you or someone drops food, whether it’s touched the floor for five seconds or five minutes, do yourself a favour and toss it in the bin in the name of food safety, no debates needed.
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