Here’s bad news for strong believers of the “five-second rule.” Researchers from Rutgers University in New Jersery debunked the famous rule on picking up and eating food that fell on the floor before it reaches five seconds.
In a recent study published in the American Society for Microbiology journal Applied and Environmental Microbiology, researchers found out that the “safe” five-second window in eating spilled food is false.
“We decided to look into this because the practice is so widespread,” said Donald Schaffner, professor and extension specialist in food science, in a news release. He added that the subject, despite being seemingly “light,” is a concern since many people believe in it, with references even in pop culture.
The study revealed that moisture, surface type and contact time are all factors that can contribute to the contamination of food by bacteria.
The researchers tested four surfaces, namely ceramic tiles, wood, carpet and stainless steel. The study involved four different types of food: bread, bread and butter, watermelon and gummy candy. They also varied the contact times of the food to the surface.
Schaffner and her partner, graduate student Robyn Miranda, used two media to grow Enterobacter aerogenes, a non-pathogenic cousin of salmonella that naturally occurs in the human digestive system.
The results showed that watermelon was most contaminated, while gummy candy was the least.
“Transfer of bacteria from surfaces to food appears to be affected most by moisture,” Schaffner said, adding that when food is wetter, the risk of transfer is higher.
Longer contact times also usually result in more bacteria in the food. Carpet also showed low bacteria transfer rates, compared to stainless steel and tile.
While the five-second rule can still hold true in terms of contact time, other factors must also be considered in terms of food safety.
Schaffner said that the five-second rule is a “significant oversimplification” of the bacteria transfer to food. “Bacteria can contaminate instantaneously,” he said.