Saturday, January 28, 2006

What does yeast eat?

So, how do we measure how much carbon dioxide is being produced by yeast? Well, we don't measure it absolutely but we can compare how much yeast is being produced by one sample relative to another sample.

Here's what we did:
Put equal amounts of warm water (115F) and the substance being tested into a clean soda bottle. Add 2 teaspoons of yeast and put a balloon on top. They will look like this.
As long as the balloons are the same size you can compare how much CO2 gas is coming off of the mixture. In 15 minutes or so you should have some filling up and looking more like this:
We tried grated apple, grated potato, sugar, salt and flour. My K'er drew pictures of the balloons at different points in time; that was the measuring part for her. Guess which things the yeast will eat and why, emphasize only changing one thing at a time (water temp, amount of yeast, water and testing material stays the same) and you'll have yourself an honest to goodness science experiment! And from that smile you can tell - it's even fun.

If you give it a shot, let us know your results!
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