Double Dip Chip Challenge Jack Spangler turns double-dipped chip dip into Petri pudding... and email to friend
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Submitted by Jack Spangler

The younger experimenter for this project is none other than Jack Spangler. After seeing an episode of Mythbusters, Jack didn't necessarily see eye-to-eye with the show's conclusion - double-dipping is no big deal. So, he set out to perform his own version of the Double-Dip Chip Challenge.

1. Purchase a sixteen ounce carton of Ranch dip from the store.
2. Purchase a bag of potato chips.
3. Prepare three Petri dishes with nutrient agar (using the technique we learned in third grade). Allow the liquid to harden in the Petri dishes overnight. Keep the Petri dishes cover so that bacteria cannot get into the agar.
4. Divide the Ranch dip equally into three clean bowls.
5. Label the first bowl “plain dip.” Label the second bowl “DOUBLE-DIPPED.” Label the third bowl “LICKED THE WHOLE THING.”
6. Get a large chip and dip it into the “plain dip” bowl. Only dip the chip once. this will be the "control."
7. Get a large chip and dip it into the “DOUBLE-DIPPED” bowl and put the chip into my mouth. Bite it in half. Then dip the chip again into the bowl. I have successfully completed the double-dip.
8. Pick up the third bowl labeled “LICKED THE WHOLE THING” and do what the label says - lick the whole thing! I will poke my tongue into every nook and cranny of the bowl. Do lots of licking until my Mom is totally grossed out.
9. Use a clean cotton swab to swab a sample of the “plain dip.” Smear this onto the first Petri dish and label it “plain dip.”
10. Use a clean cotton swab to swab a sample of the “DOUBLE-DIPPED” dip. Smear this onto the first Petri dish and label it “DOUBLE-DIPPED.”
11. Use a clean cotton swab to swab a sample of the “LICKED THE WHOLE THING” dip. Smear this onto the first Petri dish and label it “LICKED THE WHOLE THING.”
12. Place the Petri dishes in a place that is between 75oF - 80oF for two days. Watch for the bacteria to grow.
13. Compare the amount bacteria that has grown on each of the samples.

Observations

Plain Dip - After three days, i noticed that there were some things growing. this could be from the good bacteria in the dip, but I'm not really sure.

Double-Dipped - the double-dipped dish didn't look as bad as the plain dip until i started to count all of the bacteria colonies. there are at least 28... maybe more.

Licked the Whole Thing - this is just one giant, disgusting dish of petri pudding. there are so many colonies that they started to fuse together.

How does it work?

The hypothesis was easy to prove - my double-dipped bowl of dip had less bacteria than the "whole mouth" bowl. But I was surprised to see how much bacteria was really in the double-dipped bowl. if you think about it, the chip just touches your mouth for a split second before you plunge back in and get some more dip.

i was really surprised to find how much bacteria there was in the "plain dip" petri dish. when i read more about bacteria in food, i discovered that there is a lot of good bacteria in food. i wonder if there would have been as much bacteria if I would have used salsa instead of a sour cream kind of dip?

double-dipping your chip is not a good idea. some people would say it's not that big of a deal, but my tests show that the bacteria from my mouth still grew... and it's gross!

Additional Information: Food science students at Clemson University examined the effects of double-dipping using volunteers, wheat crackers and several sample dips. They found that three to six double dips in one bowl transferred about 10,000 bacteria from the eaters' mouths to the remaining dip. That means if you're at a party and three to six people double-dip their chips, any chip you dip may pick up at least 50 to 100 bacteria. The research was published earlier this year online in the Journal of Food Safety.

Additional Info

Jack used Comic Life to present his science fair project...