How can I prove/disprove the five second rule?

Question

For the upcoming science fair, I'm toying with the idea of such an experiment.
How do you think I could compare the bacteria in food samples? Is there some kind of solution that I could use with a food sample that could determine the level of contamination?
Oh, and please keep this relatively simple. I'm in the eight grade.

Answer 1

If you talk with your biology teacher, he (or she) might be able to help you get a hold of some bacterial plates. They are petri dishes with a gelatin and bacterial nutrient layer at the bottom.

You'd basically put a piece of food on the floor for 0, 5, 10, 15, etc. seconds then use a sterile swab (your bio teacher could also help you get some of these) to wipe the food then a separate plate (to transfer any bacteria from the food onto the plate).

After growing for a day or two, you'll be able to look at the plates and determine how much bacteria was on the food.

Long ago, I did a similar project, but I tested sponges to determine how much bacteria they hold and how best to clean them.

Answer 2

"The 5 second rule" is nonsense. Think about it. When food falls on the floor or the ground, the bacteria on that surface have already made contact. Time on the floor has nothing to do with that part. Time becomes a factor if the food is not cooked and/or eaten right away. The bacteria picked up in the landing will begin to multiply on the food if it is not used immediately but will not significantly increase in a mere 5 seconds. At any rate, the food is contaminated instantly on contact and just gets worse the longer the food is around for the bacteria to grow. As to easy tests, there are none. Lab cultures and growth counts take time. Too much time for an instant display of results.

Answer 3

You should check out my local news article talking about the five second rule at: http://www.10tv.com/?sec=home&story=sites/10tv/content/pool/200707/533354228.html

It states that researchers have found that many things dropped could not collect enough germs in five seconds to make a person sick. They explained that an apple slice could be safe to eat for up to 30 seconds after being dropped and a Skittle could be safe to eat after one minute!