Dropped
food on the floor? Can you pick it up and eat it? The long-held urban myth that
if you pick food up from the ground within five seconds – known as the ‘five
second rule’ – it is safe to eat. Researchers at Aston University put the rule
to the test.
Research
students at the School of Life and Health Sciences at Aston University in
Birmingham, England, monitored the transfer of common bacteria (E. coli and
Staphylococcus aureus) from the floor to different kinds of food over a period
of 3 to 30 seconds. They determined that food picked up a few seconds after
being dropped is less likely to contain bacteria than if it is left longer.
Bacteria are least likely to transfer from carpeted floors to the food, and are
most likely to rapidly transfer from laminate or tiled surfaces.
The
biology students tested dropped toast, pasta, biscuit, and a sticky lolly. The
result showed that time was a significant factor in the transfer of bacteria
from floor to food – yes, 5 seconds – and that the type of floor covering had
an effect on the bacteria. Professor Hilton, the research supervisor,
maintained that consuming dropped food still carried a risk of infection but there
was evidence that transfer from indoor flooring surfaces is weak with carpet,
posing the lowest risk of bacterial transfer.
The
researchers also surveyed people to determine who believed the ‘five second
rule’ and found it acceptable to eat dropped food. Their survey showed that 87%
of respondents said they would eat dropped food (or already had done so) within
five seconds.
The
researchers only carried out tests on indoor flooring, the number of people
surveyed wasn’t stated, and it isn’t clear how much bacteria it takes to receive
an infection or contamination - nor whether the toast was buttered and what
side was on the floor – so it may only serve to confirm what most people
already know.
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