Gelatin Gum Drops

The Gelatin Gum Drops experiment that follows provides another demonstration of how absorption of water can result in a gel-like solid. Students can perform this experiment in the classroom or at home.

Supplies needed:

• Flavored gelatin powder (do not use sugar-free varieties)
• Bowl or cup
• Small shallow dish (~2 inch in diameter)
• Water
• Eyedropper
• Plastic fork
• Paper plate

Procedure:

1. Place a layer of gelatin powder in the small dish (~1 inch thick).

2. Pour water into a separate bowl or cup.
3. Using an eyedropper, squeeze a small drop of water in the center of the gelatin.

4. When the first drop disappears/absorbs, add another drop on top of the first one. Continue until you have placed 6-8 drops on the same spot.

5. Use a plastic fork to scoop under the gelatin wet spot and lift it out of the powder. Place the wet gelatin lump on a paper plate. You have made a gum drop!

SAFETY NOTE: Do not eat the gum drop. It is never advisable to eat something produced during a science experiment.

Observations:

• How was the gum drop made?
• Why did the water drop disappear?

Candy gum drops are made from sugar, corn syrup and a gelling agent (a natural polymer!) such as starch, pectin, natural gum or gelatin. The gelling agents swell when they absorb water, forming a gel. These materials can absorb many times their weight in water.

Gelatin is a macromolecule; it is derived from the collagen obtained from boiled animal hooves, bones and hides. Addition of water and sugar to gelatin results in the formation of a temporary network gel structure. The network is held together by weak hydrogen bonds only when the temperature is lowered to ~40°F. When the temperature is raised, the bonds break and the network collapses, releasing the water.

Gelatin desserts date back to the 1890's when Charles B. Knox (Knox Gelatin) packaged it for use in desserts. The first patent on gelatin dessert was granted in 1865 to Peter Cooper, founder of Cooper Union University. Jell-O® was first sold by Pearl B. Wait in 1897. Jell-O® is about 85% sugar, 10% gelatin and 5% artificial flavors.