Acetaldehyde

Tim Bulin

Tim Bulin

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Checked the last couple beers I kegged, picked up strong green apple flavor...now I WAS having trouble getting the yeast(WLP800) to drop, think maybe I should have given them more time to clean up and not just kegged after a few days at FG.

Now, today I'm brewing a batch of California Common(Shore Leave), pulled the kegs out of the keezer where they were lagering and I think I'm going to save a bit of wort(unhopped), split it into 2 1qt jars and pitch a little Mauribrew 497 in each. I'll add it to the kegs when it gets good and active. Hopefully salvage the beer.
 
Never really had that problem. I usually let it ride for 3 days after a stable SG, then cold crash for 3 days. So it gets nearly a week before kegging
 
Sunfire96 said:
The only batch I've had bad green apple aroma was infected by a scratched bucket
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I don't believe it's infection, came out of seperate fermenters and seperate starters. Think this can be mainly attributed to a lack of patience on my part. I got used to one yeast, have used Mauri 497 pretty much as a house yeast for the last year or so, and racked the primary a bit early on them I think. I have a plan to get rid of it, if it works, great. If it doesn't work, I'm really not out anything.

Gave this some thought. Niether keg has cleared so I'm going to:

1. degass the kegs, I snapped a blowoff tube to each of the gas posts.
2. let the kegs raise to room temp(65 degrees in the basement)
3. add 1pt of actively fermenting wort(just to try to "wake up" the yeast still in suspension and 4oz of table sugar to each keg.
4. purge headspace and seal kegs with 20psi CO2.
5. wait 2 weeks.

Hopefully they clean up and drop. If it doesn't work, I'll start over on these beers. Next time I'll give the yeast a little more time to do it's job(or just go back to using the faster yeast).
 
Was the yeast you used a 34/70 derivative? I have gotten that (not super strong though) with 34/70 on lighter colored beers and it usually “lagers” away for me. Not sure on what Wyeast it is, never used that Wyeast strain.
 
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Sound like a good plan Bulin hopefully the repitch of yeast clean up that phenol for you.
Hey geletin works wonders at keezer temps you can push it in via the liquid out post or if you've got a prv in through that.

Anyhow I look forward to seeing how you get on
 
Josh Hughes said:
Was the yeast you used a 34/70 derivative? I have gotten that (not super strong though) with 34/70 on lighter colored beers and it usually “lagers” away for me. Not sure on what Wyeast it is, never used that Wyeast strain.
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WLP800 is listed as "Pilsen Lager", actually an ale strain from Czech Republic(Urquell?), I've used both 34/70 and Diamond lager some and had really nice results with both. Had some sulpher and/or esters from Mauribrew 497 that disappeared with lagering. These were some of my first brews with WLP800 since the very first batch I ever made(did so many things wrong with that one, it was basicly undrinkable LOL)

The Brew Mentor said:
Sounds to me, if I'm reading it right, that you'll over carbonate the kegs.
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I think they'll be ok, I can always bleed off the extra CO2 if I get a bit high.
 
I'm not sure you can get rid of that aroma/flavor once it's in the beer.

There are two different compounds that produce apple flavors in beer. Acetaldehyde, which is green apple, as you mentioned and ethyl hexanoate or ethyl caproate which produces a red apple aroma/flavor. The green apple is always consider a flaw and is produced by the yeast and bacteria. It can be cleaned up by the yeast if the fermentation is healthy, but if too much is produced, it can't finish the job. Reintroducing active yeast will clean up some diacetyl, but I'm not sure it would work for acetaldehyde.

Red apple is very common in lager yeast (not sure if your yeast was a true lager). Budweiser is known for it in their beers. It's not considered a flaw in an American lager in lower levels and is often mistaken for acetaldehyde. Once that aroma/flavor is in the beer, it usually stays in the beer, but I noticed that lagering can reduce it a bit.
 
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I never bottle or keg sooner than 4 weeks. The beer may be "done" but it still needs time for the yeast to reabsorb the off flavors it put into the beer. What the yeast giveth ....it taketh away given time. Also never talked about enough .... fermentation temperatures. Investing in a fermentation chamber will really help with final product and off flavors like this .....
 
Bulin's Milker Bucket Brews said:
No creo que sea una infección, salió de fermentadores separados y entrantes separados. Creo que esto se puede atribuir principalmente a la falta de paciencia de mi parte. Me acostumbré a una levadura, he usado Mauri 497 más o menos como una levadura de la casa durante el último año más o menos, y he atormentado la primaria un poco antes de ellos, creo. Tengo un plan para deshacerme de él, si funciona, genial. Si no funciona, realmente no estoy fuera de nada.

Pensé en esto. El barril de Niether se ha despejado, así que voy a:

1. Desgasificar los barriles, rompí un tubo de soplado a cada uno de los postes de gas.
2. deje que los barriles suban a temperatura ambiente (65 grados en el sótano)
3. agregue 1pt de mosto fermentado activamente (solo para tratar de "despertar" la levadura aún en suspensión y 4 oz de azúcar de mesa a cada barril.
4. purgar el espacio de la cabeza y sellar barriles con 20psi CO2.
5. espere 2 semanas.

Esperemos que limpien y caigan. Si no funciona, comenzaré de nuevo con estas cervezas. La próxima vez le daré a la levadura un poco más de tiempo para hacer su trabajo (o simplemente volveré a usar la levadura más rápida). [/CITA]

It could be pollution or a diastatic problem.
It would use the last stage of primary fermentation under pressure. Only that the 20psi pressure is low, place 30psi and raise the temperature to the maximum temperature range accepted by the yeast. This safely reduces fermentation defects. But I don't think it solves everything.
Do not keep the sludge in contact with the beer for a long time, remember that under pressure the fermentation is faster. Control your density and transfer as quickly as possible.
Go ahead and tell us how it went.

Best regards
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Yeah I think autolysis takes a bit of time I personally are not too fazed about leaving the beer on the trub.

I know HBers who ferment and serve in the same vessel I'm sure they'd quit that method if the last pint or three tasted foul every time.

I have found fermenting under pressure doesn't = faster ferment yes it does at elevated temperatures.
Actually I've observed a little under attenuation from fermentation under pressure.
Yes maybe fermenting under a bit of pressure may have reduced any green apple esters in fermentation I'm not sure I don't know enough about it .

Just my 2c
 
When everything has gone well I also serve it from the keg. But it is a good practice to separate when the fermentation has not been correct

Please keep us updated.
Best regards
 
Causes:
We will go on to list the most frequent causes by which beer can be contaminated:

1) It can be caused by the yeast strain used (some produce more than others).
2) By the premature termination of fermentation.
3) Contamination by infection of the bacterium (acetobacter).

How to avoid acetaldehyde:

We will list how to avoid acetaldehyde contamination in the previous section.

1) We will have to choose a yeast strain suitable for the type of beer we are brewing, (in some styles the acetaldehyde flavor is sought).

2) Contamination by premature termination of fermentation can occur in two different ways:

– By the depletion of the oxygen of the must by temperature changes and premature flocculation.

Acetaldehyde is an intermediate compound in the formation of alcohol,
if fermentation is stopped at the time of the transformation of glucose into alcohol at the acetaldehyde stage,
it produces a fruity taste and aroma (green apple) that will disappear with more conditioning time.

– By the exposure of alcohol to oxygen.

Causing its oxidation and thus giving flavors to immature green apple.

3) Contamination by acetobacter infection can be avoided with proper cleaning and disinfection of the processing equipment.

One of the examples of beer where this "defect" flavor is sought is the Budweiser where it is present in a 6/8ppm.
 
Viejos Cañones said:
One of the examples of beer where this "defect" flavor is sought is the Budweiser where it is present in a 6/8ppm.
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This myth is still floating out there that the apple flavor in American Lagers (Bud and Coors) is acetaldehyde. Mitch Steele, who worked for Anheiser Busch, has said many times that Budweiser tests for this compound and is not allowed to get to high in their beer. Kunze, in his book, Technology: Brewing and Malting, has set the flavor threshold of acetaldehyde at 25ppm, acceptable levels in beer are 8ppm or less.

The compound that produces the apple flavor American lager is ethyl hexanoate and is a natural product of their yeast. It has a red apple flavor, much different from the green apple of acetaldehyde (which can also smell musty). Some find red apple desirable and pleasant, but I still hate it.
 
Well, just pulled a sample of the Putin Huylo, green apple taste is, for the most part, gone. Think I might be able to detect just a hint of it, but I'm not sure. Only problem with the beer now. is after repitching it with 497, it has that funk in the aroma that I seem to always get with that yeast until it has lagered a bit. AND as @The Brew Mentor called it, it's a bit overcarbed right now, I can bleed off a little co2 until it gets right though. Probably needs 3 weeks additional lagering now...at least I dodged a dumper.
 
Bulin's Milker Bucket Brews said:
Well, just pulled a sample of the Putin Huylo, green apple taste is, for the most part, gone. Think I might be able to detect just a hint of it, but I'm not sure. Only problem with the beer now. is after repitching it with 497, it has that funk in the aroma that I seem to always get with that yeast until it has lagered a bit. AND as @The Brew Mentor called it, it's a bit overcarbed right now, I can bleed off a little co2 until it gets right though. Probably needs 3 weeks additional lagering now...at least I dodged a dumper.
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you can keep that carbonic a while longer, do not cause alterations to this yeast, if the sample gave it satisfactory, cool it, as if it were after the dry hop (in presure ). Stabilize with cold 5C 3-5 days, decrease pressure take another sample. Surely everything will be a little better. Then define CO2 level and pressurize to achieve the desired one. Time will do the rest. You can consume it directly from the keg or Bottles isobarically. Avoid O2 completely in this batch.

Congratulations. Very good perseverance.

Cheers
 
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