You are relishing a tasty, delicious cookie, but because you are distracted and your mind is wandering elsewhere, the cookie slips from your hand and it comes tumbling to the ground. It stays there for no more than two seconds and you quickly pick it up. After all, it hasn't been five seconds, right?
Some people might tell you the five-second rule isn't real. It could go sideways: dismissal or fervent justification. In the end, you would either finish eating your tasty cookie, or just throw it away.
Although it may seem like an urban myth, two NASA engineers say that the five-second rule does exist, but whether you should still eat the dropped food or not depends on different factors.
"Free Cookies In The Name Of Science"
A new segment of "The Quick and the Curious" delves deeper into the matter.
Hosted by Mark Rober, a NASA engineer, "The Quick and the Curious" is aired on the Science Channel.
Mike Meacham, also a NASA engineer, joins Rober for the particular episode.
In the video, Meacham goes out in the streets holding a tray of free cookies, calling out to passersby to get one.
"Free cookies! Free cookies in the name of science," jokes Meacham.
He then finds a bearded man seated on a table. Meacham tells him about the free cookie, but there is a condition: the person has to eat the cookie after it has been dropped on the pavement.
Just imagine the germs. But Meacham picks up the cookie quickly and tells the unfortunate person about the five-second rule. The man thinks it's okay to eat it.
Meacham asks another one of the passersby, "That was less than five seconds. You want to eat it now?" To which the person replies, "No."
The NASA engineer then bumps into a couple. He drops the cookie, and asks the man if he would eat it. The woman prevents the man from eating, but the latter says, "It's fine. Look!" He then proceeds to blow air into the cookie, shake off the dust with his hand and take a bite off the tasty treat.
The Science Behind The Five-Second Rule
Did the man just make the biggest mistake of his life by defying the woman and eating the cookie? Well, it depends, Rober says.
"The 'five second rule' is really the '30 second moisture and surface rule'," explains Rober.
According to Rober, the amount of moisture on your food and the kind of surface where it will fall both greatly contribute to how much bacteria will be picked up.
When food flops down to the ground and stays within the five-second rule, it will indeed pick up tiny amounts of bacteria.
But when the dropped food is moist and remains on the ground for more than 30 seconds, it will collect 10 times the amount of bacteria that dry food pick up after three seconds.
And that is indeed bad. Rober says bacteria such as E.coli, listeria and salmonella all love wet environments, and absorb water in order to get nutrients they need to grow and multiply.
Aside from the condition of the food, the surface where the food is dropped is equally important.
In the experiment, food dropped on rugs were found to collect less bacteria than food dropped in linoleum. It's because the rugs' woven tufts indicate that less surface area is touching the dropped food.
Still not convinced? A Birmingham Aston University study also found that time is a significant factor on the transfer of bacteria from floor to food. The report also explained that bacteria is less likely to transfer from carpeted surfaces.
So for the most part, the five-second rule is indeed legit. If you do drop the cookie on the ground, make sure to count the seconds.
Watch the video below.
