Food dropped on floor safe to eat if picked up within 3 secs
Many of us might have picked up a piece of dropped food from the floor, given it a quick blow and assumed it was still safe to eat.
It is second nature to apply the age-old pseudo-scientific 'three second rule' on such occasions, telling ourselves we're safe if the food hit the floor only momentarily.
The idea that food is not contaminated if it is retrieved quickly has been believed for many years - but there has not been extensive proof that this is the case.
Now though, the doubt is out as scientists have finally investigated the theory to discover whether the rule is fact or fiction.
Manchester Metropolitan University (MMU) tested five food items to see whether the three-second rule could be trusted.
Bread with jam, cooked pasta, ham, a plain biscuit and dried fruit were all dropped on the floor and left for three, five and 10 second intervals.
These were selected as they are commonly eaten foods and all have different water activity levels; a key factor in whether items will sustain bacterial growth in the three seconds before they are picked up from the floor.
After the study, the foods were examined to ascertain whether or not harmful bacteria found on the floor was then found to be growing on the dropped food.
The study revealed that dropped foods with a high salt or sugar content were safer to eat after being retrieved, as is less chance of harmful bacteria surviving on such items.
Eating processed food from the floor poses the lowest risk - one of its few benefits - given that it generally contains such high levels of sugar and salt.
Both the ham, a salty product, and the sugary bread and jam fared well in the test. When retrieved from the floor within three seconds, the foodstuffs showed little sign of bacterial growth.