Food Hygiene: Is the 5 Seconds Rule a Myth?

10 months ago

As children, my mum would tell us not to pick any food that falls to the ground, and when we ask why? she would say the devil already had a taste of it. Well, as we grew older, we realize that the devil isn't eating any of those foods, but for every of such myth, there might be a possible truth having a different explanation and so we hit the 5 seconds rule.

While the origin of this rule is not clear, but it can be traced back to Genghis Khan who was the Medieval ruler of Mongolia. According to my reading, Genghis Khan created the Khan Rule which said that any food that fell on the ground could still be edible, provided that Khan allowed it. The Khan was regarded as a person with high standard amd so, allowing for anyone to eat a food after it had fallen to the ground meant that the food was still good for consumption.

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According Brad Alan Lewis in 1995, in his ovel Wanted: Rowing Coach stated that if a food falls into the ground it can still be picked and eaten within 20 seconds. When I saw this, I began to wonder where the 20 seconds timing came from and what was his basis for the timing and expiration and what will really happen when food drops on the ground.

According to Marcus Teremius Varro in 300 BCE, he said that certain minute creatures which cannot be seen by the eyes, which floats in the air, enters the body through the mouth and nose, causing serious diseases. When he said this, he believed certain unseen creatures were causing diseases and it wasn't until Robert Hooke and Anton Van Leeuwenhoek, that we were able to identify these unseen creatures as microscopic organisms.

Taking a look at the 5 seconds rule, I decided to take a look at the work of Robyn Miranda, PhD, and Donald W. Schaffner, PhD. In their research study publish in 2016 titled "Longer Contact Times Increase Cross-Contamination of Enterobacter aerogenes from Surfaces to Food", they were able to contaminate 4 different surfaces (Stainless steel, Indoor - Outdoor Carpet, Ceramic glazed tile, and Maple Laminate Wood) to understand which food and surface was good for bacteria adherence using Enterobacter Aerogenes which is a non-pathogenic bacteria but stick to surfaces. The foods used for the study were white buttered bread, Watermelon, White Un-buttered bread and Gummy bears and they were all disinfected.

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The researchers were able to make 128 contact scenarios and replicating scenario 20 times to give 2560 contact. and they came to a conclusion that bacteria sticks to a food that falls on any surface almost immediately but then their ability to attach to the food items depend on the type of food items. The watermelon was the worst with bacteria attachment as the wetter the food the more it can attach to the microorganisms while the Gummy bear was the least food item with bacteria attachment showing that moisture is important in determining how fast bacteria attaches to food item when they fall on surfaces or on the ground. Also, the longer the food spent on the surface, the more bacteria it got, but the Indoor - Outdoor Carpet transported the least bacteria to the food item since the food item wasn't lying completely on the surface compared to other surface.

At the end of the research, the scientists agreed that the 5 seconds rule is real as longer contact time between food and a surface meant more transfer of microbes to the food, but then the nature of the food and the type of surface in contact is important but then the time at which microbes will attach to food items that make contact with surfaces is immediately making the rule also wrong in that point.

While the study did affirm that longer contact times resulted in more bacterial transfer, making the 5-second rule somewhat valid, it also highlighted that bacteria attach immediately upon contact. This finding challenges the rule, emphasizing that both the food's nature and the surface type play crucial roles in microbial transfer. Therefore, while the 5-second rule may offer a rough guideline, it's not a foolproof standard for food safety.