Project Spotlights

Food Myths Exposed: Why the Five-Second Rule Should Be the No-Second Rule

It happens all the time – the last chip in the bag drops onto the floor, so you quickly snatch it up, and eat it while quoting the five-second rule to your friends. But how legitimate is the five-second rule? Dr. Paul Dawson, a professor in the Department of Food, Nutrition, and Packaging Science, and his Creative Inquiry team are exploring this popular eating habit myth and other old wives’ tales, such as double-dipping and drinking from the milk carton, to see whether we’re putting our bodies at risk or if we’re just saving time and food.

Dr. Dawson noted, “Working with the students on the Creative Inquiry team is refreshing and exciting for me since we combine student creativity with hands-on experiments to challenge common myths and claims about food and bacteria.” The team consists of undergraduate students who investigate claims about food and public health.

Creative Inquiry is the best way for students to gain not only practical research experience, but also self-confidence in the ability to problem-solve.

Ashley Stone, a student on the project, explained, “Creative Inquiry is the best way for students to gain not only practical research experience, but also self-confidence in the ability to problem-solve. I learned invaluable experimental techniques that I know will help me when it’s time for the job hunt.”

Dr. Dawson and associates began their series of experiments by determining how long germs can survive on the ground. They found that the bacteria Salmonella typhimurium could survive for up to four weeks on dry surfaces and still be transferred onto food. The team then tested bologna and bread on wood, tile, and carpet to determine how fast and how many bacteria got onto the dropped food. The study verified that bacteria transfer to the food instantly – so much for the five-second rule. Bacteria spread the best on the tile flooring, with just about 70 percent of the floor bacteria population transferring onto bologna and nearly half onto bread. Biological sciences major Paul Landeene mentioned, “I was impressed with what I learned, but even more impressed by the faculty’s effort to involve and inform all the team members.”

When the team looked into drinking milk directly out of the carton, the results were astonishing. Typically, milk spoils in the range of 100-1000 CFU/ml (colony forming units, that is, the number of bacteria that could form colonies). Already ten days into the experiment, there were roughly 400 CFU/ml in the carton that had been directly drunk out of, well into the spoiling range. This was more than eight times the number of bacteria found in the milk carton that had been consumed using cups. Although drinking straight out of the carton may not always make you sick, it will surely make your milk go bad sooner.

More recently, the team tackled a frequent topic of debate at parties – whether or not double-dipping is okay. They found that sauces that had been dipped in once had less than 10 CFU/ml; however, sauces that had been double-dipped in were far more contaminated. Thinner sauces seemed to pick up the most bacteria from double-dipping, such as salsa, which had nearly 1000 CFU/ml from double-dipping.

Still, other favorites such a cheese and chocolate were not free from the double-dipping bacteria party, with roughly 160 CFU/ml and almost 200 CFU/ml, respectively.

The most recent Creative Inquiry team examined the yearly tradition of blowing out candles on the birthday cake. On the small cakes that still had their candles lit, there was on average 200 bacteria capable of forming colonies while the cakes that had their candles blown out had roughly 3000 bacteria. Now who wants some cake?

The next time you’re thinking of picking up that dropped chip, just don’t do it. These projects have shown that some food myths simply aren’t true. The studies by this Creative Inquiry team have already helped to improve public health and awareness, but what will they look at next? Whether it be if worms really do drill holes through apples or how bad sharing a drink is, this Creative Inquiry team is sure to find where the bacterium lies.

By: Thomas Larrew (Decipher Issue 1, Fall 2012)