The wrong 5-second rule about contaminated food

Many people believe that food falls to the ground and can be picked up within 5 seconds, but a recent study denies this.

According to Science Alert, after conducting many experiments, the team at Rutgers University, New Jersey, USA revealed the truth about the "5-second rule" in the report published in Applied and Environmental Microbiology magazine on 2/2. 9.

"We decided to study this issue because this is a popular concept. The topic seems normal but we want to draw conclusions on a scientific basis, " said Donald Schaffner, professor and science expert. shared food.

"Rule of 5 seconds" assumes that when food falls to the ground, if it is picked up quickly, it can still be used safely because bacteria need time to move. However, by testing many types of food that fall on different surfaces to calculate the rate at which bacteria spread, the team found they could cling to food in less than a second.

The bacteria can cling to food in less than 5 seconds.(Photo: Lori Adamski Peek).

The team tested on four different types of surfaces: stainless steel, ceramic tiles, wood and carpet. They cultivate Enterobacter aerogenes, a safe, non-pathogenic bacterium that has the family name of Salmonella, in the laboratory and covers surfaces. After that, many foods such as watermelon, bread, butter bread, marshmallows are released on these surfaces for a period of 1 second, 5 seconds, 30 seconds and 300 seconds.

The research team conducted 128 different experiments repeated in 20 times, a total of 2,560 measurements to analyze the level of infection of each food sample. The results show that bacteria spread to food immediately, not up to 5 seconds. The biggest factor related to bacterial infection is the moisture content of the food, followed by the type of surface it falls on.The longer the time the food is on the surface, the more bacteria will stick.

"Bacteria have no legs, they move with steam. The more wet the food, the easier it is to get infected. In addition, prolonged contact time increases the amount of bacteria that attach to food," Schaffner explained.

The team said that even though food infects more in a long time, within 5 seconds, bacteria can still cling to food , especially wet, sticky foods like candy or watermelon. These are the foods with the highest level of infection in the experiments.

"The 5-second rule is an over-simplification of what actually happens when bacteria attach from the surface to food. They can spread immediately ," Schaffner said.

The interesting thing is that the food that falls on the carpet is the safest compared to other surfaces because the carpet's structure minimizes contact with food.