Still Have Leftover Halloween Candy? Use It For Science!

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Ever wonder how many different dyes are used to color Skittles?
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Halloween has come and gone, but piles of candy remain. You have two options: Eat it all and risk a serious sugar coma, or get seriously creative with some candy-themed science.

We asked employees at various science museums what experiments they like to do with leftover candy. Get crackin'.

The classic "what does candy REALLY taste like"?

"Your sense of taste is actually really limited," explains Julie Yu, senior scientist and director of the Teacher Institute at the Exploratorium in San Francisco. A lot of what we perceive as flavor comes from smell, because our tongue can only taste a few things: sweet, salty, sour, bitter and savory (and fat). You can test this by plugging your nose, putting candy in your mouth, and unplugging your nose. Then, see if the flavor changes.

What's in Your Candy?

You can test foods for starch using ingredients from a drug store, according to Debra Bailey, co-coordinator of the Micro World Investigate Lab at the North Carolina Museum of Natural Sciences. Just crush up a candy and mix it into water. Then, add a few drops of the solution into a cup of iodine (yes, the antiseptic). If it changes from amber to black, you've got starch!

Bailey says you can also test for Vitamin C, glucose, and proteins with paper indicator strips for sale on Amazon.

Skittles Chromatography:

Ever wonder how many different dyes are used to color Skittles? Well, OK, me neither. But now I really want to know, and Kelly Thornton, youth and family programs manager at the Pacific Science Center, says it's not too hard to find out. You need candy, a coffee filter, a pencil, aluminum foil, salt, water, toothpicks and cups.

  1. Cut the coffee filter into strips.
  2. Place different colored Skittles on a piece of foil, leaving space between the candies. Use your finger to drip a bit of water on top of each Skittle and wait for the color to dissolve.
  3. Collect water from beneath the Skittle by dipping in a toothpick. Place a dot of the color about half an inch from the bottom of the coffee filter. Use a different strip of filter paper for each color.
  4. Mix one cup of water with 1/8 teaspoon of salt. Pour a layer of this solution into the bottom of the cup, and place the filter paper in it, with the water just touching the bottom of the coffee filter.

The salty water will pull the dye up the paper with capillary action. Different dye molecules will move different distances, so the colors will separate. If multiple dyes color one Skittle (or M&M, or Canadian Smartie), you'll know!

Try random experiments:

Rebecca Reilly likes to mutilate her candy: "Cut it up, melt it, dissolve it, test the acidity ... things like that."

She's the food science coordinator at the Oregon Museum of Science and Industry, and her favorite candy experiments are open-ended ones. "One great thing about candy is it's full of things you wouldn't expect, which makes it great for science experiments! It reacts in really strange ways," she says.

Reilly shared some of her favorite things to do with candy, and a bit about what those things can teach you:

  1. Dissolve it: Dissolving candy tests the principle "like dissolves like." Oil, for example, dissolves in fats, not water, so you need an emulsifier like soap to clean greasy dishes. Reilly suggests dissolving different candies in water, oil, vinegar, or baking soda water. Goals: Try to dissolve candy corn, or the letters on M&Ms and Skittles.
  2. Melt it: "Putting all your candy in the oven is actually really fun," says Reilly. Things that are pure sugar will bubble and caramelize. Reilly isn't sure why Twizzlers don't melt and Smarties (or Rockets, if you're Canadian) turn clear. Try it at home and make your own hypothesis. Important note: Don't put Jawbreakers in the oven. Reilly says the different layers have different melting points, and the scalding molten interior can burst out of the Jawbreakers' hard shell and seriously hurt you.
  3. Test for acidity: Boil some water and pour it over diced purple cabbage. Let it sit for at least five minutes, until the water turns purple. Pour the juice into a bunch of cups. Purple cabbage juice, explains Reilly, is a natural pH indicator that will turn "all colors of the rainbow" depending on what's in it. Acidic things turn the cabbage juice orange, red and pink. Bases turn it blue, green or yellow. Reilly says she's done this experiment with just about everything in her kitchen.
  4. More acid experiments: Spoiler alert for the above experiment — everything sour contains acid. Sour taste receptors are sort of a built-in pH meter. And as you might recall from volcano science experiments, if you mix an acid (vinegar) with a base (baking soda water), you get bubbles. The same thing happens when you put sour candies in baking soda water. Reilly says sour gummy worms are really fun "'cause they'll float up on the bubbles and dance."

Bonus Candy Craft: Candy Scat

Have you ever noticed that chocolate sprinkles look like mouse poop? Well, the North Carolina Museum of Natural Sciences has. Megan Chesser, a teacher education specialist, likes to hide animal scat (yes, poop) in schoolyards. She leads teachers on a scavenger hunt, and dares them to make observations about the scat. They break it open to see what's inside and smell it.


"Finally, I say, 'You know what's a great way to tell what this is made of? Eating it.' And then I pop it into my mouth," says Chesser. The secret is, it's chocolate, mashed up to look like it came from a raccoon.

Chesser takes the teachers back to a classroom to make edible scat of their own. They mold tootsie rolls into different shapes for different animals. To make omnivore poop, like a bear has, she mixes in nuts and berries. For bird and reptile scat, Chesser suggests rolling tootsie rolls in powdered sugar to get that authentic patina. For carnivores, add some shredded wheat for hair. Chesser says it's a great way to get kids thinking about food webs.

Some candies don't need much work. Hershey's Kisses look like elk scat, and if you chop up chocolate sprinkles it looks like cockroach poop (or "frass," which Chesser delightedly informed me is the technical name for arthropod poop.)

For larger animals, "leftover brownies from a Halloween party are great to mold into tubular scat," says Chesser. "A box of brownie mix goes a long way."

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