Acetaldehyde is driving me bonkers

[Buccaneer]

I've brewed 14 batches now and I think it's safe to say that 12 of them have had acetaldehyde aromas that took weeks, if not months, to dissipate. I've tried various things to try to correct the problem:

• Letting the beer sit on the yeast for 2 weeks
• Letting the beer sit on the yeast for 3 or more weeks
• Fermenting at cooler temperatures
• Fermenting at warmer temperatures
• Trying different yeasts (US-05, US-04, WLP001, WLP017, WB-06)

None of it seems to have made any difference.

Early on, I made a 6 gal batch - 5 for the keg, 1 to bottle. For that batch, the 1 gal of bottled beer seemed to be rid of the acetaldehyde in about half the time of the keg. The only difference that I could see is that the bottles got a bit of priming solution and the keg did not. I've subsequently added a bit of priming solution to the keg whenever I keg a beer and it seems to help.

I'm guessing that maybe I'm managing the yeast improperly. When I put the wort into the fermenter, I vigorously pour back-and-forth many times to aerate. It gets pretty foamy from this, so I'm assuming something is happening. I recognize that there's a limit to the amount of O2 that's getting into the wort via this technique, but even Palmer suggests that this should be ok.

When I'm using dry yeast, I hydrate it first for at least 20 minutes before pitching. For the White Labs liquid yeast, I usually just shake up the tube and then pitch as is. My batches are 2.5 or 5 gal, so my understanding is that this should be sufficient.

So, is there something I can do to fix this or do I just have to live with a long conditioning process?

[chalmers]

Strange stuff... Longer primary and cool conditioning usually fixes this right up. I wonder if oxidization could be an issue? From "the site that shall not be named", it talks about acetylaldehyde as being an a possible oxidization product of ethanol... http://www.homebrewtalk.com/wiki/index.php/Acetaldehyde" onclick="window.open(this.href);return false;

[LiverDance]

where does your water come from? and how much yeast are you using?

[Buccaneer]

Strange stuff... Longer primary and cool conditioning usually fixes this right up. I wonder if oxidization could be an issue? From "the site that shall not be named", it talks about acetylaldehyde as being an a possible oxidization product of ethanol... http://www.homebrewtalk.com/wiki/index.php/Acetaldehyde" onclick="window.open(this.href);return false;

Define 'cool conditioning'. I usually bottle/keg the stuff and let it sit in my basement for a couple of weeks - it's probably 18C on average. I should probably measure that, just to be sure. After that 2 weeks, if it's a keg I then put it in my keezer. For bottles, I put in a few at a time.

Regarding oxidation, I'd like to think I'm handling the hot wort appropriately, but perhaps not. After boiling, I engage my immersion chiller and bring it down somewhere in the 20C-22C range. I occasionally stir very gently to move the wort around so that it'll cool faster. Once I get it down to that range, I then do my aeration and let it sit in my temp controlled fermenter at the desired fermentation temp for maybe 60-90 minutes, then pitch the yeast. Maybe I need to wait to do the aeration...

[Buccaneer]

where does your water come from? and how much yeast are you using?

I've been using Big 8 water because my house has a full system filter set-up of some sort - not RO, but something different. I need to look up the details. I haven't been ready to start mucking with building my own water yet, so going with Big 8/Scotsburn seemed like the easiest solution.

For yeast, I typically use a single package - 11g of dry yeast or a full tube of liquid. I have been wondering if maybe I'm underpitching.

[LiverDance]

Under pitching is a possibility I would bump up the numbers for anything past 1.054 or so, 2 pack for dry or a starter for liquid. Also If I remember correctly the big 8 water has a strange salt makeup, maybe try RO water with some of your own salts to get the calcium and sulfates up.

[Hobbitfu]

In my experience 1 pack of dry yeast is fine for anything except big beers (8% and up). Liquid yeast will have less cell count than a package of dry so I generally do a starter with that (unless the beer is lighter beer around 5%).

Water composition could play a factor. But hard to judge without knowing all the specifics. Personally I would pitch the yeast right after chilling and aeration. The first phase is lag and growth so if it is slightly higher than main fermentation temp this isn't a problem.

Based on repeat experience of your issue though it seems to me that water may be the biggest possible factor without knowing your whole process setup. Unless you make all imperials I don't think you are grossly underpitching especially with the dry yeast, yet still have a problem? Get a water report and use bru'n water spreadsheet.

[CartoonCod]

No need to aerate with dry yeast. I just pitch directly, but you can rehydrate and probably get better results. Are you sure the problem is acetadehyde? You could bring it to a Brewnoser meeting for a taste test.

[Buccaneer]

Are you sure the problem is acetadehyde? You could bring it to a Brewnoser meeting for a taste test.

That's an excellent question. Any time I notice the smell of green apples, I hand a sample to my wife and daughter to sniff. They identify it, without prompting, every time. My wife also identifies other aromas at the same time, so I'm reasonably confident in her report. But still, I should bring it around for some more 'expert' opinion.

[CorneliusAlphonse]

Temps fluctuate much during fermentation?

[Buccaneer]

Temps fluctuate much during fermentation?

Not much, no. I set my temp controller to my desired temp and it has 1C either side. So if I set it for 19C, it'll roam between 18 and 20. And it rarely moves that much.

[CorneliusAlphonse]

Dunno then. Only time I had trouble with it was brewing extract with no temp control in an apartment that varied 10° higher in the day than the night

[darciandjenn]

I think the issue of oxidization that chalmers brings up is worth investigating as well. You talk about your pre-pitching aeration procedure, but is it possible that you're exposing your fermented beer to excess oxygen. Do you rack to a secondary? Is your autosiphon (if using) in good working order? How much headspace is in the carboy / keg / bottle, etc.

Is this specific to certain styles of beer?

[Buccaneer]

I think the issue of oxidization that chalmers brings up is worth investigating as well. You talk about your pre-pitching aeration procedure, but is it possible that you're exposing your fermented beer to excess oxygen. Do you rack to a secondary? Is your autosiphon (if using) in good working order? How much headspace is in the carboy / keg / bottle, etc.

Is this specific to certain styles of beer?

Exposing the fermented beer to excess oxygen? I'm pretty sure I'm not. If I'm kegging, I rack directly to the keg. If I'm bottling, I rack to a second bucket, then to the bottles. I've not yet ever racked to a secondary. I can detect the apple aroma immediately when I open the fermenter after 2-3 weeks and I can taste it in the sample I take to measure FG, so this is happening before the finished beer is touched as part of any packaging.

I don't have an auto siphon - just a regular one. I prime it with sanitized water, put the black-capped end into the bucket, let the siphon go until all of the water is out, then put the loose end into the keg/bottling bucket/attach bottle filler/whatever. I don't splash anything around and the siphon seems to work smoothly.

Regarding styles, my stout didn't appear to have it, but pretty much everything else has - blonde, amber, wheat, IPA, APA...

As I said at the beginning, the aroma has pretty much always cleared up, but it takes (what I think is) a long time - usually a couple of months until I stop noticing it.

[CartoonCod]

What is your typical final gravity?

[LiverDance]

http://www.carolinabrewmasters.com/PDF/ ... _Guide.pdf" onclick="window.open(this.href);return false;

[Buccaneer]

What is your typical final gravity?

Usually in the 1.010 range.

http://www.carolinabrewmasters.com/PDF/ ... _Guide.pdf

A useful document. Some things I noticed:

"Oxidation of finished beer might convert ethanol back into acetaldehyde. In this case, acetaldeyhde is usually accompanied by other oxidation and/or age-related defects."

I don't notice any other effects, so maybe I'm ok in this area. I'm no expert, of course, so I should seek the opinion of more qualified individuals.

"Reduce head pressure during fermentation and conditioning to allow acetaldehyde to blow off."

What does that actually mean? On a (perhaps) related note, I use a chest freezer as a fermentation chamber, so all gases emitted during fermentation just kind of sit around. Could this be some of the problem?

[jason.loxton]

Wierd. I've never had acetaldehyde issues, so I have no personal advice to add, and it sounds like you're covering all the bases that I'd recommend from the literature. That said, in addition to bringing a sample in to have someone taste to make sure you've IDed the problem right, I'd consider grabbing a Festa Brew kit and fermenting that as you normally would, i.e., same yeast pitch, etc. This would allow you to check your process to where the problem lies, i.e., eliminating all the pre-fermentation side of the process as a potential contributor if you've still got the issue.

[Buccaneer]

I'd consider grabbing a Festa Brew kit and fermenting that as you normally would, i.e., same yeast pitch, etc. This would allow you to check your process to where the problem lies, i.e., eliminating all the pre-fermentation side of the process as a potential contributor if you've still got the issue.

A great idea. I think I shall do exactly that.

[Buccaneer]

Now that the homebrew review has taken place, I'd like to revisit this. Both beers I submitted had some acetaldehyde, particularly the younger of the two.

Of the three sources of acetaldehyde, I'm pretty certain it's either a problem with fermentation or how I'm transferring the finished beer into kegs or bottles.

I'm not sure what else I can do with fermentation that I haven't already tried. I'm open to any and all suggestions, of course.

So, that leaves me with the transfers. As I study this, I've read lots of stuff about purging containers with CO2. I do not currently do this. However, I am careful not to splash and I make sure the end of the tubing is below the surface.

I notice most of the apple aroma when I open the fermenter before packaging.

It's really irritating.

[Woody]

I've suffered from this as well. It comes and goes. I pick it up in the aroma as you have noted in yours and also my wife and I both can taste the apple. It happened in my last brown. It drives me nuts too. If I bottle condition it, it goes away. I've had a half brick of US05 in the freezer since Dec which I have been using. I try and over pitch but wondered if my storage technique was poor decreasing cell count. Others I've talked to store in the freezer without issue. The times it's happened to me I pitched warm 25C and cooled overnight to 18C etc to ferment. I think I'm really going to work on my pitch and fermentation temperature. Thanks for sharing.

[CartoonCod]

You mentioned earlier that your pitching temp was around 20-22 degC. I doubt this is your problem, but you could try pitching a bit cooler at around 18 degC or so.

[Celiacbrew]

What type of fermentor are you using and what type of airlock?

until you identify what is causing your issue, you can try what the Germans do and krausen your beer at the end of fermentation to clean it up. Take some of your extra wort after the boil and put it into the freezer. Add a little yeast to the thawed wort about 12 hours before packaging. At packaging mix the mini starter into your fermentor and then transfer or put it in your keg and transfer. The active yeast will be like a supercharged version of the bottle conditioning.

[CorneliusAlphonse]

Did you ever try the festa brew thing? You using extract by chance?

[Buccaneer]

What type of fermentor are you using and what type of airlock?

Just a simple plastic bucket. I use a 3-piece airlock (http://www.everwoodavebrewshop.com/3-Pi ... ir-3pc.htm" onclick="window.open(this.href);return false;).

Did you ever try the festa brew thing? You using extract by chance?

I had forgotten about this. I'm going to pick one up in the next couple of days and get it going.

My first few batches were extract/steeping grains. The last 20 batches have been all-grain.