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Old 03-14-2012, 02:39 AM   #1
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Default how does alcohol turn to vinegar

im a cider maker and ive read several threads about how if you dont sanitize properly or if you dont keep oxygen out of your cider it will turn to vinegar.

1) how exactly does alcohol, such as cider or wine, turn into vinegar

2) what factors cause wine or cider to turn into vinegar, (ex: oxygen contamination, bacterial contamination)

im a chemistry major so an explanation at the molecular level would be nice

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Old 03-14-2012, 02:41 AM   #2
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Bacteria turn ethanol into acetic acid.

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Old 03-14-2012, 02:46 AM   #3
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C2H5OH (Ethanol)+ O2 → CH3COOH (Acetic Acid) + H2O


Acetobacter + oxygen = bad for beer

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Old 03-14-2012, 02:47 AM   #4
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Certain bacteria (like acetobacter) ferment ethanol into acetic acid.

C2H5OH + O2 → CH3COOH + H2O

So good sanitation and keeping things anaerobic prevents beer and wine from becoming vinegar.

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Old 03-14-2012, 02:51 AM   #5
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Originally Posted by cshamilton View Post
Certain bacteria (like acetobacter) ferment ethanol into acetic acid.

C2H5OH + O2 → CH3COOH + H2O

So good sanitation and keeping things anaerobic prevents beer and wine from becoming vinegar.
And aceterobacter only can make vinegar when both alcohol and oxygen are present (as shown in the formula). That's why it's important to sanitize, as well as top up carboys to prevent oxygen in the headspace.
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Old 03-14-2012, 02:58 AM   #6
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wow, thanks for the fast feed back.

i was worried because i have a batch of cider brewing in a bucket with around 2-3 inches of head space and its fermenting so slowly (less than 1 point a week) that ive been worried about O2 contamination turning my cider into vinegar. but since im good with sanitation im not to worried now.

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Old 03-14-2012, 03:00 AM   #7
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wow, thanks for the fast feed back.

i was worried because i have a batch of cider brewing in a bucket with around 2-3 inches of head space and its fermenting so slowly (less than 1 point a week) that ive been worried about O2 contamination turning my cider into vinegar. but since im good with sanitation im not to worried now.
Well, oxygen is a danger once you get to about 1.020 or less, especially if it's going that slowly. What's the current SG?
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Old 03-14-2012, 03:19 AM   #8
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well, oxygen is a danger once you get to about 1.020 or less, especially if it's going that slowly. What's the current sg?
1.015, i want it to drop 3 more points before bottling.
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Old 03-14-2012, 01:12 PM   #9
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1.015, i want it to drop 3 more points before bottling.
It might drop more than 3 more points if it's not done, depending on yeast strain and the OG. And then you could have bottle bombs if you're not careful.
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Old 03-14-2012, 01:21 PM   #10
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most of the ciders I have done have finished close to 1.0, and had one actually go below. Be very careful if you bottle at 1.015

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