# Fermentation

**URL:** <https://boards.straightdope.com/t/fermentation/231827>\
**Category:** Factual Questions\
**Created:** [March 1, 2004, 1:39am UTC](https://boards.straightdope.com/t/fermentation/231827 "2004-03-01T01:39:47Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Freiheit](https://avatars.discourse-cdn.com/v4/letter/f/e8c25b/32.png) [@Freiheit](https://boards.straightdope.com/u/Freiheit)\
**Post date:** [March 1, 2004, 1:39am UTC](https://boards.straightdope.com/t/fermentation/231827/1 "2004-03-01T01:39:47Z")

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I got curious about fermentation today. I knew that there is a reaction between sugar and yeast, but I wondered what the chemical equation would look like. I don’t know if I was expecting (yeast) + (sugar) --\> (ethanol) + (CO2), [I know yeast isn’t just a chemical] but I saw

```auto

C6H12O6 --> 2(CH3CH2O) + 2(CO2)

```

This doesn’t look like the equations I’m used to. I see two products, and expect two reagents.

Why exactly does the sugar break down like that?

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**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\
**Post date:** [March 1, 2004, 1:51am UTC](https://boards.straightdope.com/t/fermentation/231827/2 "2004-03-01T01:51:15Z")

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I’m not a chemist, but your equation isn’t balanced.

It should be:

C6H12O6 - yeast -\> 2CH3CH2O **H** + 2CO2

Count up the atoms on each side, there are 6 carbons, 12 hydrogens, and 6 oxygens, on both sides.

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<div class="post-metadata">

**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\
**Post date:** [March 1, 2004, 2:18am UTC](https://boards.straightdope.com/t/fermentation/231827/3 "2004-03-01T02:18:24Z")

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To attempt to answer your question, **glycolysis** is the 10 step process that takes place inside the yeast and isn’t listed for the sake of brevity.

> [@](#):
>
> Yeast, when under anaerobic conditions, convert glucose to pyruvic acid via the glycolysis pathways, then go one step farther, converting pyruvic acid into ethanol, a C-2 compound.

[link](http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookGlyc.html)

[Detailed diagram of glycolysis](http://www.people.virginia.edu/~rjh9u/glycol.html), complete with reagents.