19. The five second rule is…
The closest approximation of the truth is that the five second rule is a myth.
The second closest approximation of the truth is that the five second rule is a thing, and it depends on the nature of the food and the nature of the surface you drop it onto.
Bacteria transfer in moisture. A wet, bacteria-rich surface like a wet kitchen cloth will transfer bacteria to a wet food — like watermelon — very effectively. A dry bacteria-rich surface like a stone benchtop will transfer bacteria to a dry food — like a dry biscuit — very ineffectively.
Also, a damp surface is more likely to carry bacteria than a dry one. So your wet kitchen floor is probably more filthy than your dry, sunbleached outdoor tile table.
But the topography of the surface is important too. Of the food and surfaces tested by Rutgers University, the combination with the least contamination was a dry gummy sweet dropped onto carpet. The worst was watermelon dropped onto tile or stainless steel.
You can read more about it here: https://www.sciencedaily.com/releases/2016/09/160909112406.htm
Copyright © Damian Clarke, 2019