Sweet Tooth Science: How To Teach Science With Gummy Bears

I remember the days when hard candy was the #1 item in the candy store.  Peppermints, butterscotch, fruit-flavored hard candies… everything seemed to be made ready to crack a tooth with a single bite.

Recently, we have learned that to make hard candy you need to boil most of the water out of a sugar water solution until nearly all of the water is gone.  The hotter the solution, the harder the candy because:

The more water syrup contains, the softer the candy will be

But as I grew older, I started seeing a change in the types of candy available in the stores.  All of a sudden, a new kind of candy started to emerge…

GUMMY CANDIES

The gummy bear was the first to catch my attention, followed shortly by the gummy worm.  And since that time, an entire gummy “race” has emerged that has DIFFUSED into the pharmaceutical world as well with “gummy medicines.”

You should know by the name alone that these sugary treats will have virtually no hard crystals in them whatsoever.

However, keeping a sugar solution from forming crystals is not an easy task.  We learned previously that by removing the heat from a boiling sugar solution very quickly, we can create a transparent hard candy.  But we don’t want to bust a tooth on a gummy bear.  So how do we keep the final product soft and chewy?  Well, the four basic concepts of science will definitely be something we will need:

CORN SYRUP TO THE RESCUE

In order to keep crystals from growing inside sugar syrup, cooks add corn syrup into the solution.   The long glucose chains that make up corn syrup get in the way of every ATOM within the solution, especially the sugar molecules!

Basically, the corn syrup keeps the free sugar molecules from binding together by getting in their way.  Corn syrup also gives any “species” of gummy organisms a little chewiness as well!

Most gummy candies are made with an equal mixture of sugar molecules and corn syrup.  Cooks also throw in a couple of different molecules as well:

Gelatin and Pectin

Gelatin is a protein made of long chains of ATOMS which resemble a piece of spaghetti when placed into a warm corn syrup/sugar solution.  However, when gelatin cools, it coils up like a telephone cord.  When you add a large amount of gelatin to the soon-to-be gummy bear solution, all of these “cords” get tangled up with each other as they cool and help to turn the cooling liquid into a firmer gel.

Pectin is a molecule typically found within the cell walls of plants and is made up of long strands of “glucose-like” molecules.  This molecule helps to create a smaller (and tasty) “web” of gel within the cooling syrup solution.

With the addition of corn syrup to remove crystallization and gelatin/pectin to create a gel, cooks can easily prepare an army of gummy creatures!  And because of these additional ingredients, most gummy candies are made up of a lot of water (almost 15%.)

IT’S TIME TO RUN AN EXPERIMENT!

The next time you are at the store, pick up a small bag of whatever gummy critter you like and bring him home.

Set him inside a glass of water for a day or so and watch what happens…

YOUR CUTE, INNOCENT-LOOKING GUMMY BEAR WILL SWELL TWO TO THREE TIMES ITS SIZE!

Not a single ATOM was created to cause the swelling of your gummy bear.  That would go against the LAW OF CONSERVATION.

So what caused the massive growth? Steroids, protein shakes, an all-night pork rind binge?  NOPE!

Even though most gummy candies are made up of 15% water, there is a much higher amount of water molecules OUTSIDE the gummy bear as it sits in your glass of water.

And, since ATOMS and molecules tend to move from high concentrations to low concentrations, the water molecules DIFFUSE into the gummy bear.  The DENSITY of the gummy bear will remain the same because it still contains all of its original ATOMS – even though its size increased drastically!

If, for some freakish reason, the gummy bear were to DIFFUSE all of this water into itself and NOT increase in size, then its DENSITY would increase.  That is not what happens in the swelling of your gummy bear!  When the number of ATOMS inside an object increases AND its size increases as well, its DENSITY will not increase at all!

POP QUIZ

I’m not going to tell you how to do this (let’s see how imaginative you are) but let’s say we want to revive our gummy bear back to its original size?  How do you think you could do it?  Feel free to drop me a line and let’s see what you come up with!

Learn more about chemistry concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!

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