Most of the people have followed the 'five-second rule' after dropping something tasty on the ground. But, is it safe for consumption? It may not be so, says a new study.
Researchers at Rutgers University in New Brunswick, N.J put the five-second rule to test and found that contamination with bacteria can occur in less than one second.
‘Foods with high moisture content that dropped on the floor had the highest bacterial contamination. Germs transfer more easily to wet or moist foods.’
"The five-second rule is a significant oversimplification of what actually happens when bacteria transfer from a surface to food," said study lead researcher Donald Schaffner, a professor and extension specialist in food science.
"Bacteria can contaminate instantaneously," said Schaffner.
The researchers studied the food contamination by dropping different textures of foods such as watermelon, bread and gummy candy on different surfaces such as ceramic tile, stainless steel, wood and carpeting.
The researchers contaminated each of these surfaces with a salmonella-like bacteria called Enterobacter aerogenes
for various lengths of time. The surfaces were allowed to dry completely before each type of food was dropped.
The team evaluated the transfer of bacteria from the surface to food after letting it sit for less than a second, five seconds, 30 seconds, 300 seconds. Overall, the researchers assessed 128 different scenarios 20 times for a total of 2,560 measurements.
Longer exposure to dirty surfaces and moisture made the germs contaminate the food worse. The researchers found that contamination could occur in less than one second.
"Transfer of bacteria from surfaces to food appears to be affected most by moisture," said Schaffner.
"Bacteria don't have legs, they move with the moisture, and the wetter the food, the higher the risk of transfer. Also, longer food contact times usually result in the transfer of more bacteria from each surface to food," he said.
The highest contaminated food was watermelon, and the least contaminated was gummy candy. Germs are more easy to transfer to wet or moist foods.
Foods dropped on the carpet sample had less contamination than those dropped on tile or stainless steel. The food items dropped on wood had more variable levels of contamination.
"The topography of the surface and food seem to play an important role in bacterial transfer," Schaffner said.
The study was published in Applied and Environmental Microbiology.