how does alcohol turn to vinegar - Home Brew Forums

Register Now!
Home Brew Forums > Home Brewing Beer > Brew Science > how does alcohol turn to vinegar

Reply
 
Thread Tools
Old 03-14-2012, 02:39 AM   #1
kamkamdac
Recipes 
 
Jan 2012
camarillo, California
Posts: 57


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

 
Reply With Quote
Old 03-14-2012, 02:41 AM   #2
AZ_IPA
PKU
HBT_LIFETIMESUPPORTER.png
 
AZ_IPA's Avatar
Recipes 
 
Jun 2008
The Cold Part of AZ
Posts: 52,621
Liked 8689 Times on 6985 Posts


Bacteria turn ethanol into acetic acid.

 
Reply With Quote
Old 03-14-2012, 02:46 AM   #3
MalFet
/bɪər nɜrd/
HBT_LIFETIMESUPPORTER.png
 
MalFet's Avatar
Recipes 
 
May 2010
NYC / Kathmandu
Posts: 8,632
Liked 1474 Times on 975 Posts


C2H5OH (Ethanol)+ O2 → CH3COOH (Acetic Acid) + H2O


Acetobacter + oxygen = bad for beer
__________________
"Be excellent to each other." -Benjamin Franklin

 
Reply With Quote
Old 03-14-2012, 02:47 AM   #4
cshamilton
Recipes 
 
Mar 2011
South Central Michigan, MI
Posts: 308
Liked 18 Times on 16 Posts


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.
__________________
My most recent recipes: http://www.brewtoad.com/brewers/191

 
Reply With Quote
Old 03-14-2012, 02:51 AM   #5
Yooper
Ale's What Cures You!
HBT_ADMIN.png
 
Yooper's Avatar
Recipes 
 
Jun 2006
UP of Michigan, Winter Texan
Posts: 69,406
Liked 7836 Times on 5490 Posts


Quote:
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.
__________________
Broken Leg Brewery
Giving beer a leg to stand on since 2006

 
Reply With Quote
Old 03-14-2012, 02:58 AM   #6
kamkamdac
Recipes 
 
Jan 2012
camarillo, California
Posts: 57

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.

 
Reply With Quote
Old 03-14-2012, 03:00 AM   #7
Yooper
Ale's What Cures You!
HBT_ADMIN.png
 
Yooper's Avatar
Recipes 
 
Jun 2006
UP of Michigan, Winter Texan
Posts: 69,406
Liked 7836 Times on 5490 Posts


Quote:
Originally Posted by kamkamdac View Post
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?
__________________
Broken Leg Brewery
Giving beer a leg to stand on since 2006

 
Reply With Quote
Old 03-14-2012, 03:19 AM   #8
kamkamdac
Recipes 
 
Jan 2012
camarillo, California
Posts: 57

Quote:
Originally Posted by yooper View Post
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.

 
Reply With Quote
Old 03-14-2012, 01:12 PM   #9
Yooper
Ale's What Cures You!
HBT_ADMIN.png
 
Yooper's Avatar
Recipes 
 
Jun 2006
UP of Michigan, Winter Texan
Posts: 69,406
Liked 7836 Times on 5490 Posts


Quote:
Originally Posted by kamkamdac View Post
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.
__________________
Broken Leg Brewery
Giving beer a leg to stand on since 2006

 
Reply With Quote
Old 03-14-2012, 01:21 PM   #10
JeepDiver
Recipes 
 
Apr 2009
Highlands Ranch, CO
Posts: 1,326
Liked 147 Times on 115 Posts


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

 
Reply With Quote
Reply
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
I froze my beer for more alcohol, but... tykreis Brew Science 4 02-12-2012 09:26 PM
Determining % Alcohol Tuckahoe Brew Science 28 06-03-2011 02:16 PM
Vinegar as an Acid Rinse? RonRock Brew Science 3 03-29-2011 07:56 PM
Did I make vinegar, or does this beer need some time. Like a year. kmlavoy Brew Science 1 11-29-2009 10:14 PM
Alcohol Content historian Brew Science 29 11-02-2009 10:33 PM


Forum Jump