Yeast, sugar and CO2 production

[gbailey00]

My second grade daughter and I conducted an experiment to see which "food" that dry active yeast "likes" better as measured by how much gas is produced (which balloon is bigger). The yeast/flour solution produced more gas than the yeast/syrup (high fructose corn syrup). Can you help us understand why the flour mixture produced more of a reaction than the pure sugar mixture?

Thanks!

[klhjbh62604]

Hello gbailey00:

Welcome to Science Buddies. What a great project to do together with your 2nd grader. Below I have provided some links for you to look at to help you better understand what is going on. Please review the information and if you have any further questions or you still want further explanation please reply to this thread.

https://www.sciencebuddies.org/science- ... background

https://www.sciencebuddies.org/science- ... background

Thanks,
klhjbh62604

[KrishnaPatel]

klhjbh62604 gave you a great start, but I just wanted to add some more information. Glucose is the type of sugar needed for yeast to ferment, so the yeast have to convert all of the other types of suger (including fructose in high fructose corn syrup) into glucose. The starch in flour is a polymer (made up of many molecules of) glucose, so all the yeast need to do is break the bonds holding the glucose together to begin digesting it, but with fructose, the yeast needs to convert it into glucose which takes longer than breaking the bonds between glucose molecules, so the fermentation of fructose takes a lot longer, and therefore, it produces a lot less carbon dioxide in the same amount of time that the yeast/flour mixture can.

I hope this helps!
Meg