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According to wikipedia, the byproducts of yeast fermenting (like done in baking it says) are carbon dioxide and alcohol (not necessarily ethanol -- the kind you can get drunk on).

If that's the case, then technically speaking does every form of raised bread have chemical alcohol in it?

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All food containing starches or sugars that is moist and exposed to yeasts (deliberately or from the wild) will have trace amounts of alcohol. This includes fresh fruit, vegetables, etc. Teetotallers beware :-) –  TFD Mar 13 '12 at 23:03
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Minor note, not all forms of raised bread use yeast... :) –  Flimzy Mar 14 '12 at 4:07
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@Flimzy Yeast is omnipresent, so any wet flour will have some yeast growing in it if exposed to normal household air –  TFD Mar 14 '12 at 8:40
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4 Answers 4

up vote 5 down vote accepted

The majority of the alcohol evaporates during baking.

McGee's On Food and Cooking says (pg 532):

In making beer and wine, the carbon dioxide escapes from the fermenting liquid, and alcohol accumulates. In making bread both carbon dioxide and alcohol are trapped by the dough, and both are expelled from the dough by the heat of baking.

I also found this report, which states that some alcohol (0.04 to 1.9%) may remain.

However, the report is from 1926, so
1. it may not be really representing modern day situation
2. the data, methodology etc. is not reported: it looks more like an informal news than a real research article, so I cannot critique on whether the results are realistic.

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All yeast fermented products contain ethyl alcohol (ethanol). Yeast produces carbon dioxide and ethanol as it metabolizes sugar. Generally, the longer the fermentation the greater amount of alcohol. Sourdough starters for instance are allowed to ferment for a long time and can form a clear liquid on top called "hooch." Hooch can reach upwards of 15%-18% alcohol by volume.

As far as the alcohol burning off, this report given by the Dept. of Agriculture shows alcohol content vs. heat and time in baking/cooking. The remaining alcohol in bread is usually negligible, but if you cut open a hot loaf you can usually smell the trace remaining.

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The basis of yeast cookery is that yeasts react with sugar to produce carbon dioxide, which aerates the dough but also produces - as a by-product - alcohol (ethanol). During heating of the dough loss of alcohol will occur - down to vanishly small amounts but not complete absence. If you are concerned about total absence of alcohol, you need to look at bread-making by different methods, for example using baking powder or just direct heat.

Following recent comments, you’re right that it is a physical process, not a chemical one, but it is one that is progressive. The dough will contain a mixture of water and alcohol. As baking proceeds, the components of this mixture will evaporate at a rate influenced by the volatility of each, and their proportions in the mixture. I would expect the proportion of alcohol in the vapour to be greater than in the liquid mixture, due to its volatility. However, this will reduce the concentration of alcohol in the remaining mixture, and this will lead to a progressive reduction in the rate of alcohol loss, giving the half-life effect. The following link has a report from the USDA about alcohol burn-off in cooking in general http://homecooking.about.com/library/archive/blalcohol12.htm

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I am curious why there would be a half-life of alcohol here. Physical processes like evaporation are often governed by simpler formulas. –  rumtscho Mar 14 '12 at 0:44
    
I believe @rumtscho is correct, the elimination of alcohol is not due to a chemical reaction, it's a physical process (evaporation). The alcohol, as far as I know, does not continue to react with anything else. –  Aaronut Mar 14 '12 at 23:02
    
Why can't I add a comment? –  Stuart Mar 14 '12 at 23:22
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@Stuart: You seem to have... and with respect to your edit, it's okay to rewrite the original part of your answer, to revise the misleading comparison to "biochemical reactions". (Also, not all reactions are first-order.) –  Jefromi Mar 15 '12 at 0:11
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I'd be extra-wary of any content on about.com. I can't seem to find this burn-off chart on the actual USDA, and the values don't make much sense at all - but, if they do show anything then it appears to be closer to a linear decline than an exponential one. –  Aaronut Mar 15 '12 at 0:31
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Yeast has many phases. In an oxygenated environment the yeast will produce carbon dioxide and water and it will reproduce, there is no alcohol. While doing this it consumes the oxygen. Once oxygen is depleted it becomes anaerobic and a completely different process takes over. It will then produce alcohol and carbon dioxide. This is called fermentation and it it only occurs in an anaerobic environment (or if there is some fatty acids present). It takes a long time for the fermentation phase to begin. It simply won't have a chance to occur in bread.

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The whole process of using microorganisms to alter a food product is fermentation. Specific yeasts will only produce alcohol in anaerobic conditions, but most yeasts commonly used in food will produce alcohol even in the presence of oxygen. source –  sourd'oh Jan 8 at 17:10
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