A newly released study may finally answer the question: Is the five-second rule valid?
According to research published in the journal of Applied and Environmental Microbiology, the answer is complicated.
Researchers from Rutgers University coated four different surfaces with Enterobacter aerogenes, a microorganism similar to Salmonella.
Next, they dropped watermelon, bread, bread with butter and gummy bears on each surface and left them there for different lengths of time.
The scientists found some bacteria transfer happens “instantaneously,” essentially debunking the idea that food is safe to eat if picked up in fewer than five seconds.
At the same time, they found contamination increased over time, lending some credence to the idea that food is safer to eat if picked up sooner.
They also found that some foods pick up bacteria faster than others. Watermelon had the highest rate, regardless of other variables, while gummy bears had the lowest.
Buttered and plain bread had similar transfer levels – meaning it doesn’t really matter whether your buttered toast falls butter up or butter down.
The researchers note that a 2005 episode of the TV show Mythbusters found no difference between food that had been left for two seconds or six seconds.
They write that their research “clearly showed that contact time does influence bacterial transfer.”
