Student Question
One of my biology 100 students e-mailed me the following question. Any insights?
When someone is baking a cake with yeast. Is the reason to coverthe yeast and let it sit so that the oxygen level becomes less in turnfermentation can take place?
10 comments:
What cakes use yeast?
See, now this is why you are so much smarter then me. When I saw this e-mail I just filed it away to think about later. Hmmm, maybe I need to cook more often.
She did ask me about bread during our review session (at least I really hope she did, because otherwise I will feel really really more stupid than I do now.
There are a few cakes-- but they'd be basically bread based cakes- that use yeast. I'm going to go check some recipes, but to my knowledge, none of them say to cover the yeast. You do mix it with water and sugar and a little flower before mixing it with the overall dough, I thought this was basically to make sure the yeast was alive before ruining all the ingredients and to get it started, but I suppose it could be to use up some of the oxygen. Will need to think about that more.
I've never made a cake with yeast, but when I use it for dough I don't cover it while it's activating, only when it is rising. I thought that was just to keep the dough moist and warm.
Hey - Jennifer Dropkin asked that question one time at KBS lunch. It was about testing the yeast - there's some word for it. She didn't realize it was to test the yeast - thought it was part of the process.
How would that use up oxygen if it's just the testing phase? Isn't all exposed to air anyway when it's added to the rest of the ingrediants?
It's called "proofing" the yeast, and I'm pretty sure it's just to get the yeast started and check that it's alive before you add it to the rest of the ingredients.
What was Erin's removed comment? Something juicy? About yeast??!!!
Why would you want to keep oxygen away from the yeast. It can't do aerobic respiration, anyway, can it?
Oh, yeast can do aerobic respiration and, apparently this is what you WANT it to do in baking (bread is not alcoholic, after all). Aerobic respiration produces CO2 faster and makes bread rise faster. http://www.dgs.edu.hk/QEF_Sc/Manuals/Biology/TM1--yeast%20resp.pdf
(Not much of a ref., but makes sense to me.)
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