It happens all the time – the last chip in the bag falls to the floor, so you snatch it up, quickly blow it off and eat it while quoting the five-second rule to your friends. But how legitimate is the five-second rule? Dr. Paul Dawson and his Creative Inquiry team have looked into it along with other food myths, such as double dipping and drinking from the milk carton, to see whether we’re endangering ourselves or if we’re just saving time and food.
Dr. Dawson and associates began their series of experiments by determining how long germs can live on the floor. They found that the bacteria Salmonella Typhimurium could survive for up to four weeks on dry surfaces and still be transferred onto food. They then tested bologna and bread on wood, tile and carpet to see how fast and how many bacteria got onto the dropped food. They found that bacteria transfer to the food instantly. Tile flooring most efficiently transferred bacteria, with 68.6 percent of bacteria transferring onto bologna and 48.7 percent onto bread.
Blowing on your food may seem like a perfectly reasonable way to get the germs off. However, according to Dr. Dawson’s work with bacteria on Swedish Fish candy, this assumption is pretty far-fetched. The Swedish Fish that were not blown on had 6.56 log (or 106.56) bacteria per milliliter (bac/ml) while the Swedish Fish that were blown on had roughly the same number, 6.44 log bac/ml.
When the team looked into drinking milk directly out of the carton, the results were astonishing! At day ten of the experiment, there were roughly 400 bac/ml in the carton that someone drank from, while in the carton containing milk that had first been poured into cups only had about 50 bac/ml.
More recently, the team tackled a common cause for debate at parties – whether or not double dipping is okay. They found that sauces that had been dipped in but not double dipped in had less than 10 bac/ml; however, sauces that had been double dipped in were far more contaminated. Less viscous sauces seemed to pick up the most bacteria from double dipping, such as salsa, which had nearly 1000 bac/ml from double dipping. Other favorites such as cheese and chocolate weren’t free from the double dipping bacteria party either, with ~160 bac/ml and ~200 bac/ml, respectively.
The most recent Creative Inquiry team examined a time-honored tradition, blowing out candles on a cake. They found that on average, cakes with candles still lit had 183.3 bacteria and cakes with the candles blown out had 2889.7 bacteria. Ready for your next birthday party?
These experiments have shown that some food myths simply aren’t true, from the five-second rule to double dipping. Dr. Dawson and his Creative Inquiry teams have helped to improve public health and raise awareness by testing variables of foods, films, antimicrobials and surfaces affecting transfer and/or survival of bacteria. Next up: do worms really drill through apples? And, what’s lurking on your local gym’s equipment? This Creative Inquiry team is sure to find where the bacterium lies.
Food mythbusting is not a tasty business.