Yeast Balloons
Yeast Balloons
How does yeast make bread rise? Yeast is a leaven. It gives off a gas that the bread dough traps to make it rise. Will yeast give off enough carbon dioxide to blow up a balloon?
Supplies:
1 packet of active dry yeast
1 cup very warm water (105-115 degrees F.)
2 tablespoons sugar
A large rubber balloon
A small (1 pt. to 1 liter) empty water bottle
The experiment:
1. Stretch out the balloon by blowing it up repeatedly, and then lay it aside.
2. Add the packet of yeast and the sugar to the cup of warm water and stir.
3. Once the yeast and sugar have dissolved, pour the mixture into the bottle. You'll notice the water bubbling as the yeast produces carbon dioxide.
4. Attach the balloon to the mouth of the bottle, and set aside.
5. After several minutes, you'll notice the balloon standing upright. If you don't see anything happen, keep waiting. Eventually, the balloon will inflate. In our experiment, as the yeast fed on the sugar, it produced carbon dioxide (the same gas we exhale). With no place to go but up, this gas slowly filled the balloon. The same thing happens when bread rises. Carbon dioxide from yeast fills thousands of balloon-like bubbles in the dough. You might ask, “How can that happen? I don't usually put sugar in my dough.” Well , flour has simple sugar molecules that the yeast reacts with to make the gas. Once the bread has baked, the dough bubbles give the loaf its airy texture.
