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Get a Rise out of Science

This article appeared in the December 26, 2014 edition of the Davis Enterprise.

 

By Lisa Justice

Special to the Enterprise

 

This week Explorit’s workshops for science-loving kids continue with topics from candle-making to different bread traditions from around the world. You can join in the fun at home by experimenting with chemistry and baking.

 

In the Breads of the World workshop, students will learn the role of yeast in bread making and experiment with other leavening agents. Yeast is the tiny organism that makes bread rise, creating air pockets that result in a light, fluffy loaf.

 

It’s also what makes traditional bread making take so long. The yeast takes several hours, or even days in the case of sourdough, to create those air pockets. That’s what’s happening when we let bread dough rise.

 

Yeast is a single-celled fungus that eats sugar and gives off carbon dioxide gas. When yeast meets the flour used in making bread, it eats the sugars in the flour and starts giving off gas. That gas creates the air bubbles in the dough. When the dough is baked, those air pockets get stuck and create the small open spaces that make the finished product so light.

 

You can witness this gas-producing power of yeast with a quick experiment. You will need: a cup of warm water, a teaspoon of sugar, a teaspoon of yeast, a funnel, a balloon, and an empty bottle. Add one teaspoon of sugar and one teaspoon of yeast to a cup of warm water, and stir it all together.

 

Take a moment to watch what’s happening. Since you know that yeast eats sugar, what do you expect to happen?

 

When it’s stored in a jar or packet, yeast doesn’t have anything to eat so it basically falls asleep. Scientists say it’s dormant. The warm water wakes the yeast up and the sugar gives it some food. As the yeast starts to eat the sugar, you should be starting to see some bubbles.

 

Now you can take advantage of those bubbles to blow up a balloon. Use the funnel to pour the liquid into the bottle. Stretch the balloon over the mouth of the bottle.

 

As the yeast keeps eating, it’ll keep giving off carbon dioxide gas. That gas needs someplace to go and it’s going to look for a way out of the bottle. Since the bottle’s

opening is blocked by a balloon, what’s going to happen?

 

Now that you know all about yeast, you’re set for all kinds of baking. But cakes and other baked goods are also light and fluffy, but we don’t put yeast in those. What’s going on?

 

Yeast isn’t a baker’s only option for creating tiny air pockets in their food. Baking powder and baking soda can also create chemical reactions that give off gas and make dough rise and baked goods light and fluffy. Just think about what happens when you mix baking soda with vinegar. Is it similar to what happens when you mix yeast with water and sugar?

 

So whatever you’re baking this holiday season, you have chemistry, and maybe even a fungus, to thank for the delightful texture of your finished products!

 

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Explorit’s coming events:

 

  • Explorit’s Beautiful World: Science and Art exhibition is open to the public every Wednesday, Saturday and Sunday, 1:00-5:00 p.m. and every Friday, 3:00-6:00 p.m.  Admission is $5.00 per person; Explorit members, teachers and children 2 and under are free.
  • Cap off your Picnic Day with Explorit at Sudwerk Brewing Company Dock Store for a fundraiser on Saturday, April 18. Details coming soon!
  • Interested in membership?  Think your Explorit membership may have lapsed?  Call Explorit at 530-756-0191 to check or sign up!
  • Birthdays are back at Explorit!  Call Explorit at 530-756-0191 for more information or to book your party.

 

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Explorit Science Center is located at 3141 5th St. For more information call (530) 756-0191 or visit http://www.explorit.org, or “like” us on Facebook at www.facebook.com/explorit.fb.

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