Five second Rule

bread Quick! Pick it up and blow! Haven’t we all dropped that tasty little morsel of food and couldn’t quite throw it in the trash? After all, if you pick it up within 5 seconds, isn’t it safe that no germs have settled on it yet? Well, think again! There is a new study that we all should heed.

Prof. Donald Schaffner and researchers of Rutgers University in New Brunswick, NJ, have reported their findings in the American Society for Microbiology’s journal, Applied and Environmental Microbiology. The Centers for Disease Control and Prevention report that around 1 in 6 people in the US get sick each year due to foodborne illness. That equates to around 48 million people. Wow! About 128,000 of these people are hospitalized and 3,000 die from this disease.

It has also been noted that bacterial cross-contamination from surfaces to food, can contribute to foodborne disease, which is why they actually investigated the topic further. They were prompted to investigate because the 5-second-rule is practiced so widespread, and they wanted their results backed by solid science.

This rule is rooted in the fact that “bacterial needs time to transfer”, but is 5 seconds to pick up, fast enough? Varying surfaces and contact times were used in the study such as stainless steel, ceramic tile, wood and carpet. The four different foods used were watermelon, bread, bread with butter, and gummy candy. Four different contact times were used as, less than 1 second, 5 seconds, 30 seconds and 300 seconds.

The bacteria used is called Enterobacter aerogenes, which is a cousin of salmonella, that occurs naturally in the human digestive system. They used tryptic soy broth or peptone buffer to grow the bacteria. The bacteria was cultivated and spread on the varying surfaces. The preparation was allowed to dry before dropping the food samples.

The transfer sequences for each surface, food, contact time and bacterial preparation were evaluated. There were 128 scenarios that were replicated 20 times each, resulting in 2,560 measurements. Watermelon had the most contaminations and gummy candy had the least. They also found that bacterial transfer from surfaces to food is affected by moisture. Bacteria moves with the moisture, since it doesn’t have legs, right? The wetter the food, the higher the risk of bacteria transfer. This rule is definitely oversimplified of what actually happens when bacteria transfers from a surface to a food. It happens instantaneously. It did prove interestingly, though, that when compared with tile and stainless steel, carpet had a lower transfer rate. This study completely disproves the 5-second rule!

Think twice (or maybe 3 times) before grabbing up that little tidbit that has fallen from your plate or fingers. Throw it out! Do not risk the transfer of bacteria from the floor that could just possibly transfer you to the hospital!
-Dr Fredda Branyon

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