Author Topic: Oxidation Story and Question  (Read 1163 times)

Offline mpietropaoli

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Oxidation Story and Question
« on: March 09, 2013, 11:30:15 AM »
So a quick story to (hopefully) benefit all.

I submitted a few beers to a comp in NYC (Homebrew Alley), one of them being an IPA I made in mid-Dec that I thought was great (judging was mid february). This beer actually came in 2nd @ a local non-sanctioned hedonistic comp in late january.

17.5 from the judges @ homebrew alley. The main thing they cited was acetaldehyde.

WTF? Then I had the last bottle I had at a club meeting in late february. Lifeless. No hops. Awful. One guy said acetaldehyde. ACETALDEHYDE!!? Green apples? How could that be possible? I pitch a ton of yeast, manage it well, etc. PLUS the beer WAS great at one point.

So I was going through my process (typing it out actually) and realized the following. Since I have been kegging, I will typically keg, then bottle with the blich beer gun, so I can free up my serving fridge which also doubles as my ferm chamber. It hit me. I love to 'quick carb'. I don't always CO2-purge when I rack to my keg. So I am shaking up my keg like a polaroid picture with oxygen in there, and diffusing both CO2 and O2 into my beer. As a long-term storer in bottles, this is a major problem.

But wait, why green apples? Why acetaldehyde? One thing I have been very diligent about in my last 20 or so brews is yeast. For the last few years. proper management, starters, pitch rate, manipulate temps well. Acetaldehyde is usually a result of improper yeast management.

Oh wait. Or oxidation....oxidation REVERSES a lot of the reactions that happen during fermentation. "intermediate" compounds that are formed during fermentation AND TYPICALLY REABSORBED rear their ugly heads as a result of oxidation (like acetaldehyde).

Lesson learned (hopefully). I need to drink the $#@!T out of my beers now so they don't have the chance to age and get worse. I have noticed this in most of the beers come to think of it.

I just carbed my 80/- and its excellent. But I didn't CO2-purge. I have heard that you can precipitate out oxygen by adding either additional campden tabs or vitamin C to the keg. I might try this, as I was planning on submitting this AWSEOME 80/- to NHC. Anyone have experience with adding a campden tab (or five) to a kegged beer to reduce oxidation? Or I might just rebrew it.

<slaps forehead>
Primary: Common Cider; Xmas FauxCAP
Kegged: Pliny Clone; Rodney's Weizenbock; RIS
Bottled: Putain Biere de Garde; 51 RIS; Glutang Clan Roggenbier
Cellaring: Biere de Mars; Flanders
Planned: Schwarz

Offline hopfenundmalz

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Re: Oxidation Story and Question
« Reply #1 on: March 09, 2013, 11:48:46 AM »
Alcohol oxidizes to form Acetalaldehyde IIRC.

Don't know about the campden or citric acid helping. Some other person might know.
Jeff Rankert
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Offline nateo

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Re: Oxidation Story and Question
« Reply #2 on: March 09, 2013, 05:43:41 PM »
I had a Tripel that developed a lactic infection. I added potassium metabisulfite to keep it from souring. I also dry hopped it. The sulfite adds a distinctive vinous sulfury quality. Not unpleasant, necessarily, but not typically found in beer. It's been maybe 6 months or so and it still hasn't aged out completely, though the dry hops do seem as fresh as ever. 
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Offline beersk

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Re: Oxidation Story and Question
« Reply #3 on: March 09, 2013, 10:27:20 PM »
I think oxidation leads to diacetyl reformation as well. I've been having an issue with diacetyl showing up in some hoppy beers. I think it's from taking gravity readings too frequently and perhaps too much headspace in the kegs since I do 3-4 gallon batches and also not treating my yeast as I should. Could be wrong though, I'm still troubleshooting this issue.
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Offline mpietropaoli

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Re: Oxidation Story and Question
« Reply #4 on: March 10, 2013, 08:34:14 AM »
does anyone have any experience in adding campden tabs (crushed, added to sanitized/boiled water) to a keg or any time post-fermentation?  My understanding is that it (or its sulfites maybe) are antioxidants that bind to the dissolved O2.  Trying to save this batch of 80/-.
Primary: Common Cider; Xmas FauxCAP
Kegged: Pliny Clone; Rodney's Weizenbock; RIS
Bottled: Putain Biere de Garde; 51 RIS; Glutang Clan Roggenbier
Cellaring: Biere de Mars; Flanders
Planned: Schwarz

Offline nateo

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Re: Oxidation Story and Question
« Reply #5 on: March 10, 2013, 09:11:04 AM »
does anyone have any experience in adding campden tabs (crushed, added to sanitized/boiled water) to a keg or any time post-fermentation? 

Yeah, that thing I just said.
In der Kürze liegt die Würze.

Offline mpietropaoli

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Re: Oxidation Story and Question
« Reply #6 on: March 10, 2013, 05:46:52 PM »
does anyone have any experience in adding campden tabs (crushed, added to sanitized/boiled water) to a keg or any time post-fermentation? 

Yeah, that thing I just said.

Got it.  Yeah, I saw two multi-syllable words in a row and just glossed over them.  Now I know Campden Tab = potassium metabisulfate.

In any event, added two tabs to the keg before I put two and two together, so we'll see how it reacts and I will post back...maybe the extreme and refreshing maltiness of my 80/- will drown out the vinous quality....  May need to rebrew this (or brew something else) to send in to NHC, but only time will tell...
Primary: Common Cider; Xmas FauxCAP
Kegged: Pliny Clone; Rodney's Weizenbock; RIS
Bottled: Putain Biere de Garde; 51 RIS; Glutang Clan Roggenbier
Cellaring: Biere de Mars; Flanders
Planned: Schwarz

Offline nateo

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Re: Oxidation Story and Question
« Reply #7 on: March 10, 2013, 05:59:58 PM »
If you're sending it to the NHC, I'd definitely rebrew it. The campden tabs will be obvious in the beer, and I don't think the judges will admire that.
In der Kürze liegt die Würze.

Offline mpietropaoli

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Re: Oxidation Story and Question
« Reply #8 on: March 10, 2013, 07:11:10 PM »
If you're sending it to the NHC, I'd definitely rebrew it. The campden tabs will be obvious in the beer, and I don't think the judges will admire that.

what a waste.  It was such a tasty brew.
Primary: Common Cider; Xmas FauxCAP
Kegged: Pliny Clone; Rodney's Weizenbock; RIS
Bottled: Putain Biere de Garde; 51 RIS; Glutang Clan Roggenbier
Cellaring: Biere de Mars; Flanders
Planned: Schwarz

Offline AmandaK

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Re: Oxidation Story and Question
« Reply #9 on: March 10, 2013, 08:15:05 PM »
If you're sending it to the NHC, I'd definitely rebrew it. The campden tabs will be obvious in the beer, and I don't think the judges will admire that.

Agreed. Sending a beer with a "band-aid" (no offense intended) on it won't do so hot, even in the first round.
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Offline ajk

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Oxidation Story and Question
« Reply #10 on: March 11, 2013, 04:23:06 AM »
I think oxidation leads to diacetyl reformation as well.
I've had that happen. I also had a slow-growing house infection once that eventually produced diacetyl in every beer it touched.

Offline hopfenundmalz

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Re: Oxidation Story and Question
« Reply #11 on: March 11, 2013, 05:14:31 AM »
I think oxidation leads to diacetyl reformation as well. I've been having an issue with diacetyl showing up in some hoppy beers. I think it's from taking gravity readings too frequently and perhaps too much headspace in the kegs since I do 3-4 gallon batches and also not treating my yeast as I should. Could be wrong though, I'm still troubleshooting this issue.
You can get oxidation if finished beer has the diacetyl precursor left in it, and the precursor oxidizes to diacetyl. This is one more reason why you want to keep the beer away from oxygen when you package. Packaging breweries purge the bottles with CO2 before filling.

Infections will also kick out diacetyl. Pedio is one that kicks out a large amount. When it is in sour beers, one has to have Brett along with it, as the Brett will use up the diacetyl.
Jeff Rankert
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Home-brewing, not just a hobby, it is a lifestyle!

Offline beersk

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Re: Oxidation Story and Question
« Reply #12 on: March 11, 2013, 07:14:09 AM »
I think oxidation leads to diacetyl reformation as well. I've been having an issue with diacetyl showing up in some hoppy beers. I think it's from taking gravity readings too frequently and perhaps too much headspace in the kegs since I do 3-4 gallon batches and also not treating my yeast as I should. Could be wrong though, I'm still troubleshooting this issue.
You can get oxidation if finished beer has the diacetyl precursor left in it, and the precursor oxidizes to diacetyl. This is one more reason why you want to keep the beer away from oxygen when you package. Packaging breweries purge the bottles with CO2 before filling.

Infections will also kick out diacetyl. Pedio is one that kicks out a large amount. When it is in sour beers, one has to have Brett along with it, as the Brett will use up the diacetyl.
The reason I don't think this issue I've been having occasionally is not Pedio is because there is no sour that accompanies it. The beer tends to turn buttery/butterscotchy in the keg after a week or so, and it's mainly noticeable in hoppy beers.  I'm thinking it's from diacetyl precursors still in the beer from poor yeast management and oxidation from taking too many gravity samples, perhaps introducing oxygen at kegging, and not giving the beer enough time in the primary (usually go 2 weeks, perhaps should start going 3).
Watch out for those Cross Dressing Amateurs!