Brettanomyces and Oxidized Compounds

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dantheman13

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I've been trying to find some information on if Brettanomyces can break down oxidized compounds, and what the effects on flavor would be. So far, I have found a wine-related paper that says that Brett can interact with oxidized ethanol to produce acetone aromas (bottom of page 4).

I have a 2 year old Lactobaccilus/Sacch only sour ale that has oxidized (shame on me), and I am curious if blending it into an actively fermenting mixed Brett culture could possibly salvage it. I probably would do this with an extract wort since the only information I can find says that I will get acetone from doing this, unless of course anyone out there can provide more information?

Thanks!
 
So far, I have found a wine-related paper that says that Brett can interact with oxidized ethanol to produce acetone aromas (bottom of page 4).

I know next to nothing about chemistry, so I might be getting this wrong. But I think the paragraph you're pointing to is describing oxidization, forming of oxidized compounds, by brett as it grows; not brett taking oxidized compounds and doing something else with them.

The most well
known to winemakers is acetic acid. This is produced during Brettanomyces growth by the oxidation of ethanol
and can lead to the formation of ethyl acetate which can have an acetone type aroma.

So "oxidization of ethanol" is a process of oxidation, not reduction, I think.
 
Another thought: that fits with the fact that when brett beers get too much oxygen, they become vinegary. Some of that may be acetic acid from acetobacter, but some if from acetic acid produced by the process described here. I think that's why, if you keep a brett starter on a stir-plate for a week or two, you get a lot of acetone smells and vinegary tastes
 
I'm afraid I can't think of anything I've read right now, but I'll keep an eye out. Most of what you hear is about brett preventing oxidation, rather than changing oxidized compounds. I assumed that meant it scavenged free oxygen molecules that would otherwise interact with other compounds in the beer, and used them in it's own processes. (In fact that thing you point to in that article is one of those processes, and I think it explains why some brett beers get increasingly tart over time as the brett produces acetic acid using oxygen.)
 
I ended up trying to add more wort to this. So, I added 2 gallons of wort on top of this 1 gallon of beer. Unfortunately, the little glass carboy that I used didn't like the rubber stopper. It fell out for an unknown amount of time, and the beer turned really acetic. I still need to dump it... I'll probably do an update on it on my youtube channel one of these days when I do dump it.
 
Wow, that was kinda sad, but you efforts were admirable. Made me bust out laughing.

So, i guess I'll try to Brett my beer and see what happens...
 
Wow, that was kinda sad, but you efforts were admirable. Made me bust out laughing.

So, i guess I'll try to Brett my beer and see what happens...

Thanks. Adding Brett to this beer wasn't entirely a thoughtless endeavor. I wouldn't have bothered if the cardboard flavor wasn't somehow aging out (I never advise adding Brett beer to poorly fermented beers in general). This was just a unique opportunity to experiment with something that I have only heard of one other brewer mention (there was a pro brewer on Fuhmentaboutit that said he adds a small amount of fresh wort to aged barrel beers so that the refermentation cleans up the oxidation).

This carboy sat in a closet unmonitored, and the airlock I am guessing for a few weeks. I have around 50 gallons of sour beer at all times, so it wasn't a huge deal for me to dump it out, but it was definitely anti-climatic for folks who have followed my vids for the last 3.5 years. To them I apologize.
 
Yeah, I totally understand.

Adding a small bit of wort makes sense to PREVENT oxidization, in the sense that it may start up fermentation again which will utilize the oxygen that may have gotten in. For the same reason, I always add a bit of sugar when kegging; eats at the oxygen and even carbs for me a little!

Something eating at that oxidized taste is a thing I've only found in this thread on one other mention on /r/homebrewing.

I'm gonna leave this oxidized hibiscus saison in the basement until I run out of carboys. Will be difficult to see if the oxidized flavour aged out or is taken care by the brett though...
 
I know that the stopper dropping out ruined the experiment, but I have heard that krausening with good old Saccharomyces_cerevisiae can "clean out" some of the oxidized compounds. It might take the edge off the Brett as well, but it would have been worth a shot.
 
I know that the stopper dropping out ruined the experiment, but I have heard that krausening with good old Saccharomyces_cerevisiae can "clean out" some of the oxidized compounds. It might take the edge off the Brett as well, but it would have been worth a shot.

So, the first time it oxidized, it was a pure Cascade Kriek dregs beer. Cascade only uses L. brevis to sour beer, but Dmitri at BKYeast blog found Brett in one bottle of Kriek. I don't know if my bottle also had Brett (or if all Cascade beers have Brett), but that might explain why the beer was more susceptible to going wet-cardboard instead of vinegar that early on. Also, the oxidation was caused by the airlock going dry. It never actually fell out, so I think the beer was mostly protected from an acetobacter infection.

When I topped up the beer with wort, I also added some beer that had Yeast Bay Brussels Brett Blend in it. On this one the airlock physically slipped out of the fermenter. Although I had a plastic bag over it, I think acetobacter still got in there somehow. Either that, or the Yeast Bay Brett really produces a lot of acetic acid when it has a lot of O2.

Sorry to leave out those details. I should probably do a follow up video to explain these little details!
 
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