Author Topic: Another Acetaldehyde Question  (Read 1861 times)

Offline blatz

  • Brewmaster General
  • *******
  • Posts: 2453
  • Paul Blatz - Jupiter, FL
    • View Profile
Another Acetaldehyde Question
« on: February 10, 2011, 07:44:49 AM »
Trying to pinpoint the cause of my recent bout of acetaldehyde in my Czech Pils.  In six years and thousands of gallons of beer, I've never experienced this flaw before, so it really has me awestruck, especially since I make a pils or dortmunder about every 4-5 batches. 

Granted, this beer is just shy of 6 weeks since brewdate and the green apple appears to be working its way out based on samplings...but I'm wondering if cold crashing my pils prior to kegging is the culprit???

I primaried for 3 weeks+ 5 days before kegging, but the last during the last 4 days, I brought the temp down from drest at 60-62 down to 40, dropping 5df each morning before work.  But crashing before kegging is not a regular practice for me - I usually don't get around to it and just keg at drest temp and then throw the kegs in the lager fridge.

Anyhow, I ferment in a 14.5 gal conical, and when I crash, I put sanitized foil with rubberband around the stopper so as not to suck back in the liquid in the airlock, but I got to thinking - did doing this with the pils cause the beer to suck in so much air that it caused oxidation which led to acetaldehyde, or am I fretting over 'green' beer that will lager away fine over the next month?
The happiest people don’t necessarily have the best of everything; they just make the best of everything they have.

BJCP National: F0281

Offline tomsawyer

  • Senior Brewmaster
  • ******
  • Posts: 1681
    • View Profile
Re: Another Acetaldehyde Question
« Reply #1 on: February 10, 2011, 08:10:45 AM »
I don't have much experience with lagers, but when I think acetaldehyde I think the fermentation wasn't quite finished.  That could be due to any number of things affecting the yeast's ability to finish in a "normal" amount of time.  Was the time you spent bringing the temp down in increments, in lieu of a longer d-rest?
Lennie
Hannibal, MO

Offline dmtaylor

  • Brewmaster
  • *****
  • Posts: 772
    • View Profile
Re: Another Acetaldehyde Question
« Reply #2 on: February 10, 2011, 08:13:21 AM »
One thing I can tell you is that I seriously, seriously doubt it could be due to air intake or oxidation.

Acetaldehyde happens to me when the yeast isn't fat and happy.  On a couple of occasions, I either severely underpitched which stressed them out, or the other time I pitched yeast that wasn't 100% healthy (kind of old yeast), so that's what I pegged the causes on.

So that's what I would consider first and foremost -- Did you do absolutely everything humanly possible to pitch a sufficient quantity of very happy yeast??  If the answer is yes, then... I'm not sure I can help.  Might be contamination!?  But definitely look at your yeast health very closely.  Could possibly also be your choice of yeast strain -- Did you use a different strain from normal?

Regarding your questions on cold crashing -- I can't say I've ever heard of that being a cause, but I suppose if the yeast wasn't happy about it..... you catch my drift.
Dave

"This is grain, which any fool can eat, but for which the Lord intended a more divine means of consumption. Let us give praise to our Maker, and glory to His bounty, by learning about... BEER!" - Friar Tuck (Robin Hood - Prince of Thieves)

Offline blatz

  • Brewmaster General
  • *******
  • Posts: 2453
  • Paul Blatz - Jupiter, FL
    • View Profile
Re: Another Acetaldehyde Question
« Reply #3 on: February 10, 2011, 08:17:02 AM »
I don't have much experience with lagers, but when I think acetaldehyde I think the fermentation wasn't quite finished.  That could be due to any number of things affecting the yeast's ability to finish in a "normal" amount of time.  Was the time you spent bringing the temp down in increments, in lieu of a longer d-rest?

That's generally true, but light lagers apparently are more prone to some other causes.  Some more details - this was brewery fresh yeast - approx 700mL of 3 day old slurry in 12gal of 1.050 OG wort.  Fermentation activity as judged by hydro, krausen and CO2 activity ceased at approx 12 days (1.012) which just shy of 1P per day - a good rate.  I let it go a few more days, then raised to d-rest for 4 days before beginning my crashing.
The happiest people don’t necessarily have the best of everything; they just make the best of everything they have.

BJCP National: F0281

Offline blatz

  • Brewmaster General
  • *******
  • Posts: 2453
  • Paul Blatz - Jupiter, FL
    • View Profile
Re: Another Acetaldehyde Question
« Reply #4 on: February 10, 2011, 08:21:19 AM »
So that's what I would consider first and foremost -- Did you do absolutely everything humanly possible to pitch a sufficient quantity of very happy yeast??  If the answer is yes, then... I'm not sure I can help.  Might be contamination!?  But definitely look at your yeast health very closely.  Could possibly also be your choice of yeast strain -- Did you use a different strain from normal?


its definitely not yeast health or strain - I use the same 830 I always do, and I get it second gen from my pro friend at a brewpub, put a healthy slug of wyeast nutrient in every boil, so I seriously seriously doubt that is the culprit.  

Contamination could be the issue, but it seems to be going away, and the beer is crystal, crystal clear - i would think it would get worse with contamination and also that the clarity would not be there?  Beer's only been lagering 2.5 weeks so far, so it could go away in the next month before i tap it.

I recall reading some 'anti-cold crashers' comments citing oxidation as one of the reasons to not CC - that's what lead to my shaky hypothesis  ;D
« Last Edit: February 10, 2011, 08:23:35 AM by blatz »
The happiest people don’t necessarily have the best of everything; they just make the best of everything they have.

BJCP National: F0281

Offline ndcube

  • Brewmaster
  • *****
  • Posts: 612
    • View Profile
Re: Another Acetaldehyde Question
« Reply #5 on: February 10, 2011, 09:48:31 AM »
Just throwing this out there as I'm sure this would have already come up....

Did you buddy experience the same flaw?

Offline dcbc

  • Brewer
  • ****
  • Posts: 269
    • View Profile
Re: Another Acetaldehyde Question
« Reply #6 on: February 10, 2011, 09:53:58 AM »
I do quite a few light lagers and always cold crash before transfer and have not (knock wood) yet had a problem with acetaldehyde.  I had a buddy who always, by my standards, transferred his beer too quickly and he routinely had issues with it.  I don't know what is causing it in your case because incomplete fermentation (or at least time for it plus cleanup) doesn't seem to be the problem.
I've consumed all of my home brew and still can't relax!  Now what!

Offline tomsawyer

  • Senior Brewmaster
  • ******
  • Posts: 1681
    • View Profile
Re: Another Acetaldehyde Question
« Reply #7 on: February 10, 2011, 10:04:39 AM »
I've read where overpitching can cause acetaldehyde production too.  Sounded like your ferm rate was normal though.
Lennie
Hannibal, MO

Offline mrcceo

  • Cellarman
  • **
  • Posts: 56
  • Location - Philadelphia Area
    • View Profile
Re: Another Acetaldehyde Question
« Reply #8 on: February 10, 2011, 10:37:11 AM »
If your confident in your pitch, time, temperature, and sanitation, did you consider wort oxygenation which can also contribute to acetaldehyde.

Offline blatz

  • Brewmaster General
  • *******
  • Posts: 2453
  • Paul Blatz - Jupiter, FL
    • View Profile
Re: Another Acetaldehyde Question
« Reply #9 on: February 10, 2011, 12:47:43 PM »
did you consider wort oxygenation which can also contribute to acetaldehyde.

if you meant prior to pitching yeast, I did oxygenate with a stone/O2 bottle setup (My SOP) for 1:45 at 48df just prior to pitching in the yeast.  if you meant upon racking to kegs, I am pretty vigilant about racking quietly and saw no areas where the finished beer would have splashed or otherwise had a high probability of picking up oxygen.  This is what led me to believe I may have oxidized through cold crashing(?)

Just throwing this out there as I'm sure this would have already come up....

Did you buddy experience the same flaw?

good point, I texted him my dilemma - he just called me and said he didn't have any issues with acetaldehyde, but he would expect it may lager away in my case, but also to throw all my saved slurries away and he'll just give me new, rather than risk carrying over a contamination if that's what it was.

like i said above, it does seem a lot better as of last night than it was a week ago, so maybe it'll disappear.  I'm just concerned as I can't pinpoint where I introduced this flaw - I make these beers all the time and this is a first for me  :(

thanks for your input guys - keep it coming!
The happiest people don’t necessarily have the best of everything; they just make the best of everything they have.

BJCP National: F0281

Offline jwatkins56550

  • Cellarman
  • **
  • Posts: 25
    • View Profile
Re: Another Acetaldehyde Question
« Reply #10 on: February 11, 2011, 04:49:52 PM »
Did you taste it after the D rest?

 I always taste the beer at the height of the d rest and see if I am satisfied with the flavor.  If I think that the yeast in suspension is masking the flavors too much( like in a light lager) I take a sample and crash it, then taste it. 

Offline blatz

  • Brewmaster General
  • *******
  • Posts: 2453
  • Paul Blatz - Jupiter, FL
    • View Profile
Re: Another Acetaldehyde Question
« Reply #11 on: February 13, 2011, 09:54:16 AM »
Did you taste it after the D rest?

can't remember if I did on this one -  doh!

update - seems like it is fading even more - I tasted a few ounces last night and it was just a hint of green.  maybe in 3-4 weeks when I am up to tapping it, it will be gone.  then again if I keep testing it, there might not be any left!  better leave it for 2 weeks before re-trying.
The happiest people don’t necessarily have the best of everything; they just make the best of everything they have.

BJCP National: F0281

Offline dmtaylor

  • Brewmaster
  • *****
  • Posts: 772
    • View Profile
Re: Another Acetaldehyde Question
« Reply #12 on: February 15, 2011, 06:38:36 AM »
Hey!  I was just reading that acetaldehyde has a boiling point of 70 F.  Then I went to Wikipedia which confirms that it boils at about 68 F!  In other words, if you warm up your beer to about 75 F for a few days, similar to a diacetyl rest, I would imagine that at least some of the acetaldehyde will bubble out.  So the trick here might be to WARM up the beer, NOT COLD CONDITION.  I don't see why this wouldn't work.  It might not be 100% effective, but should be at least partially helpful.  It can't hurt to try!
Dave

"This is grain, which any fool can eat, but for which the Lord intended a more divine means of consumption. Let us give praise to our Maker, and glory to His bounty, by learning about... BEER!" - Friar Tuck (Robin Hood - Prince of Thieves)

Offline blatz

  • Brewmaster General
  • *******
  • Posts: 2453
  • Paul Blatz - Jupiter, FL
    • View Profile
Re: Another Acetaldehyde Question
« Reply #13 on: February 18, 2011, 03:24:20 PM »
Hey!  I was just reading that acetaldehyde has a boiling point of 70 F.  Then I went to Wikipedia which confirms that it boils at about 68 F!  In other words, if you warm up your beer to about 75 F for a few days, similar to a diacetyl rest, I would imagine that at least some of the acetaldehyde will bubble out.  So the trick here might be to WARM up the beer, NOT COLD CONDITION.  I don't see why this wouldn't work.  It might not be 100% effective, but should be at least partially helpful.  It can't hurt to try!

thanks Dave - I pulled the kegs last night and will leave them at room temp through the weekend, pulling the relief valve periodically to see if that does anything.
The happiest people don’t necessarily have the best of everything; they just make the best of everything they have.

BJCP National: F0281