Chemical Forums

Specialty Chemistry Forums => Citizen Chemist => Topic started by: Porr3773 on January 11, 2010, 11:33:52 AM

Title: Yeast and Aluminum - Physical Change or Chemical Change?
Post by: Porr3773 on January 11, 2010, 11:33:52 AM

My father and I have recently made bread. The dough consists of 1/2 tbsp of yeast, 2 cups of water, 1 1/2 tbsp of salt, and 4 cups of flour. We let the dough sit overnight in a bowl covered in tin foil to let it rise but when we get up in the morning there are little pinprick holes in the Aluminum foil. The yeast does give off CO2 so I'm assuming that this is the result of gas escaping but the holes are kind of blackish around the outside... I'm wondering of this is a chemical change. I can't think of any chemical equation that would have Al+3 reacting with CO2. The only thing I can think is Al(HCO3)3...but even then I hope I'm not putting that in my bread. What do you think?

Title: Re: Yeast and Aluminum - Physical Change or Chemical Change?
Post by: billnotgatez on January 12, 2010, 05:05:34 AM

I wonder if it is the metal reacting with the salt or an acid like carbonic acid. Sometimes when wiping an aluminum surface with water I get a blackish residue.

Title: Re: Yeast and Aluminum - Physical Change or Chemical Change?
Post by: Porr3773 on January 12, 2010, 12:45:09 PM

Hmm the dough would seem to be very basic, so that seems plausible. Veryy interesting I suppose. It almost seems like the dough has a mind of its own, when it runs out of oxygen to consume it goes searching...

Title: Re: Yeast and Aluminum - Physical Change or Chemical Change?
Post by: billnotgatez on January 12, 2010, 10:50:24 PM

I thought that yeast did anaerobic??