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Speaking of yeasts, I guess it's not something that's on everyone's minds, but the reason bread rises is because yeasts die in the heat of the oven and, reactin

Speaking of yeasts, I guess it's not something that's on everyone's minds, but the reason bread rises is because yeasts die in the heat of the oven and, reacting to the deadly environmental conditions, radically increase their rate of fermentation of the carbohydrates in the dough thus releasing abnormally large amounts of CO2 in a very short time. Essentially, bread rises because of the the death throes of tiny, microscopic unicellular fungi.

gus_massa 5y ago
Are you sure? I think the yeast produces CO2 before cooking and during the initial part of the cooking (while the drought temperature is below 40°C(???)). Most enzymes a cells have a temperature where they have an optimal efficiency, so I expect the yeast not to be so efficient when the drought is too hot. But when the drought get hot the tiny bubbles of CO2 expand and when it's too hot and the drought get cooked and the structure around the bubbles is fixed like in a sponge.
mattkrause 5y ago
Are you sure about that? My impression was that fermentation outside the oven causes most of the rising, with a bit of "oven spring" from the vaporization of water in the dough. The yeast obviously die in the oven, but I don't think the death per se is critical for the leavening.
TheRealPomax 5y ago
No? They produce alcohol and CO2 during rising/proofing, and that gas has nowhere to go: it's trapped in the dough. Once heated, that trapped gas then expands during baking. The yeast dies, yes, but bread doesn't rise "because of the death throes of [yeast]", it rises because heating a gas increases in pressure, and the dough expands because of that pressure. Yes, the heat also kills the yeast, but that has nothing to do with oven spring. (And of course, the spring only "sticks" if the dough is both elastic enough to permit that expansion -for example because it has a gluten network- and developed enough that, in that expanded state, the dough can set well enough to support its own shape, rather than deflating once we remove the heat, and the high pressure gasses cool down and contract, pull the now baked bread in on itself)
cheese_goddess 5y ago
Replying to all sibling comments: oh, well. Maybe I know that wrong. I'll have to go back to find the source where I took this. I don't remember what that source was.

gus_massa 5y ago

Are you sure? I think the yeast produces CO2 before cooking and during the initial part of the cooking (while the drought temperature is below 40°C(???)). Most enzymes a cells have a temperature where they have an optimal efficiency, so I expect the yeast not to be so efficient when the drought is too hot. But when the drought get hot the tiny bubbles of CO2 expand and when it's too hot and the drought get cooked and the structure around the bubbles is fixed like in a sponge.

mattkrause 5y ago

Are you sure about that? My impression was that fermentation outside the oven causes most of the rising, with a bit of "oven spring" from the vaporization of water in the dough. The yeast obviously die in the oven, but I don't think the death per se is critical for the leavening.

TheRealPomax 5y ago

No? They produce alcohol and CO2 during rising/proofing, and that gas has nowhere to go: it's trapped in the dough. Once heated, that trapped gas then expands during baking. The yeast dies, yes, but bread doesn't rise "because of the death throes of [yeast]", it rises because heating a gas increases in pressure, and the dough expands because of that pressure. Yes, the heat also kills the yeast, but that has nothing to do with oven spring. (And of course, the spring only "sticks" if the dough is both elastic enough to permit that expansion -for example because it has a gluten network- and developed enough that, in that expanded state, the dough can set well enough to support its own shape, rather than deflating once we remove the heat, and the high pressure gasses cool down and contract, pull the now baked bread in on itself)

cheese_goddess 5y ago

Replying to all sibling comments: oh, well. Maybe I know that wrong. I'll have to go back to find the source where I took this. I don't remember what that source was.