What makes bread so fluffy?

yeastI’ll admit, I’m not a bread maker.  I’d like to think that I’m a decent cook, but in reality I’m a ‘meat and potatoes’ kind of gal.  On many occasions I like to just pop open a can of Pillsbury crescent rolls and serve it up with dinner.  One night Allie was marveling at the shear yummy-ness of the crescent rolls and asked, “Mommy, what makes the rolls so fluffy?”

I knew the answer was yeast but then she started asking her probing questions.  What is yeast?  Why does it make bubbles?  Can yeast make bread blow up in the oven?  So the mom in me decided that I should roll up my sleeves, get out the cookbook, and have Allie make some good ol’ homemade bread with me.  The scientist in me wanted to watch yeast in action in a clear plastic bottle.  I was setting us up for another experiment you can eat – works for me!

Plan:   I found an easy bread recipe that I had pinned years ago on my Pinterest board here.  Then I Google searched for how to watch yeast blow up a balloon and found great instructions here.  This is how I modified it.

First, we warmed 1 cup of water in the microwave for about a minute and a half.  Then we dissolved 1 tablespoon of sugar in the water and poured half a packet of fast acting instant yeast in the mixture.   I was expecting it to react quickly but it didn’t.  (I clearly have little experience with yeast.)  Then, I put the water-sugar-yeast mixture in a small empty water bottle and placed a balloon over the top of the water bottle opening.   I’m glad I had a few spare balloons because Allie enjoyed blowing hers up while she waited for the yeast to do it’s thing.


But when it finally happened it was pretty amazing.  Even little brother had to check things out.

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What happened:  Yeast is a fungi that feeds off sugar and produces the bi-products carbon dioxide and alcohol.  (Carbon dioxide is also made when you mix baking soda and vinegar!).  When the bread is baking, carbon dioxide makes tiny bubbles in the dough causing the bread to become fluffy.  The other bi-product, alcohol, is burned off during baking creating that yummy bread smell.

While we talked about the yeast blowing up the balloon, we started making our homemade French bread.  It was a lot of fun to mix the yeast and flour, knead the dough, and watch it rise.  Just in case you wondered,  it didn’t blow up our oven!


Here is our final product.  It tasted a lot better than it looked and the house smelled amazing!

046I love how science touches so many parts of our lives.  It even inspired me to roll up my sleeves and start making my own bread! (Don’t worry, I’ve still got plenty of crescent rolls in the refrigerator!)

Categories: 5 minute experiments, lovely conversations | Tags: , |


  • Agnes Steelhammer | January 15, 2015 | Reply

    Grandma wants a piece.

    • Tracy | January 16, 2015 | Reply

      Of course! It was delicious Me-Mo!

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