Mythbuster: Party Edition

We’ve all been to parties where we have seen people drop food on the floor and, then, immediately pick it up and eat it. Have you ever wondered whether or not food is actually safe to eat within five seconds of dropping it on the ground? How about double dipping—is it really that bad? Do germs actually spread by blowing out birthday candles? Dr. Paul Dawson, Professor of Food Science in the Department of Food, Nutrition, and Packaging Science at Clemson University, and his Creative Inquiry team, Antimicrobials and Surfaces Affecting Transfer and/or Survival of Bacteria, have made it their job to scientifically prove and disprove common food myths.

They began with simple questions and over the course of a semester they put their research plan into practice by setting up experiments, collecting data, and drawing conclusions based on the data. Dawson explained, “While the topics may seem trivial, they are designed to teach students about food science, which includes food safety, tastiness and freshness, while also learning how to conduct research, and how it affects our daily lives, even if it’s about dropping food on the floor.”

One of the teams took the popular notion of the five-second rule, which says that food that touches the ground is still safe to eat as long as it is picked up within five seconds of it being dropped. To test this myth, they had to figure out how long germs live on the floor. They found that the bacterium Salmonella typhimurium could survive for up to four weeks and still be transferred onto food. Next, they experimented with bologna and bread to see how fast and how many bacteria clung to them once they were dropped. They tested them on three different surfaces: wood, tile, and carpet. As soon as the food was dropped, the bacteria transferred immediately. 68.8% of the bacteria on the tile flooring were transferred to the bologna while 48.7% of the bacteria were transferred to the bread.

At the same party where you see that guy eat that cookie that he dropped on the ground, someone else across the room is probably eating chips and salsa, double dipping without even thinking about it. Double dipping disgusts most people, but is it a complete and total party foul? Not necessarily, but Dawson and his team found that it definitely is not the most sanitary practice. They discovered that sauces that had been dipped in but not double dipped in had less than 10 bacteria per milliliter of salsa (bac/mL), whereas sauces like salsa that had been double dipped in, averaged 1000 bac/mL.

Now that you’ve watched people eat food off of the ground and double dip, it’s time to sing “Happy Birthday” to the birthday girl and then watch her blow out her birthday candles. Does blowing out birthday candles also spread germs? This Creative Inquiry team found that the icing on birthday cakes after the candles are blown out has a significant increase in the number of bacteria: cakes with candles still lit had averaged 183 bacteria per milliliter and cakes with candles blown out had more than 15 times as much bacteria per milliliter.

Dawson’s current Creative Inquiry students have been able to think outside of the box when developing each of their different research projects and questions. Because of this, they have also learned how to collect data effectively and conduct research on topics that matter to them. Molly MacNaughton, a senior Food Science Technology student working with Dawson’s Creative Inquiry explains, “The most important thing I’ve learned is that mastering the methods for data collection is key, especially when you are trying to coordinate eight people on two different days every week. The methods are important to discovering any useful results and without everyone on the same page all of our hard work is useless.”

This year, Dawson’s Creative Inquiry is researching the transfer of bacteria from hands to popcorn and then hands to mouths as people eat popcorn and then share it with others. Stay tuned for the results, but in the meantime, just to be on the safe side, think twice before agreeing to share a tub of popcorn with your whole row of friends at the movies. Is sharing really caring?