Science Experiments From Home: Why Is Bread Soft & Full of Little Holes?
Did you know some microbes (bugs) are super important to us and help us make delicious food? We think of bugs as being 'bad' and it's true that some bugs can make us sick, but many bugs are incredibly useful to us.
One useful microbe is yeast (it has a very official sounding scientific latin name of Saccharomyces cerevisiae). Yeast is actually a fungus, other fungi that we eat are mushrooms, pretty delicious, but yeast are absolutely tiny, so tiny you need a microscope to see them, they're smaller than the size of a pinhead.
We use yeast to help us make bread, as the yeast grows and reproduces (makes more yeast cells), it produces a gas called carbon dioxide, which is the same gas that makes the bubbles in fizzy drinks and is the gas we breathe out of our bodies.
The carbon dioxide in our bread causes our bread to fizz up with bubbles. When we bake the bread the bread the little air pockets inside the bubbles are captured by the baked bread and we end up with lovely soft, springy bread.
If we didn't add yeast to our bread we would end up with very flat bread. Can you think of one type of flat bread we like to eat? *We've given you the name of one at the bottom of this blog.
For Parents & Teachers
A great control experiment to do along side is to set up a second plastic drinks bottle (a small empty fizzy drinks bottle with a narrow neck will work well).
- Add sugar and water, but don't add the yeast.
- Place the balloon over the neck of the bottle in the same way you do for the bottle with the yeast.
What you should see is the balloon over the bottle with the yeast begins to inflate as it fills with CO2 produced by the yeast, but the balloon on the bottle without the yeast does not inflate.
Bake Bread Experiment
If you're feeling creative and scientifically adventurous, you could move on to demonstrate how the yeast has an impact on bread making, by baking two types of bread with the kids, a raised bread and an easy to make, unleavened bread such as chapatti.
Have fun experimenting!
*pitta bread is a flat bread. Another name for flat bread is unleavened bread, it just means it hasn't had yeast added to it.