Getting Rid Of Acetaldehyde

[mattyra]

As for lids v film, the lids are thicker hdpe rather than thin ldpe used for film, so the permeability is much lower. SS or glass are even better. The seals on a screw thread lid with an o-ring are much better, only a small amount of o2 can get past.

Makes sense. I would love to be able to get glass equipment to brew in but money is the issue there. I always add priming sugar to my kegs as well. Not sure why, I have just had better success in doing so.

You brew AG don't you Greg?

 

[MaltyHops]

... I always add priming sugar to my kegs as well. Not sure why,
I have just had better success in doing so. ...

Gives the yeast in the kegged beer something to chew on and
use up O2 in the keg along the way.

 

[Greg.L]

Makes sense. I would love to be able to get glass equipment to brew in but money is the issue there. I always add priming sugar to my kegs as well. Not sure why, I have just had better success in doing so.

You brew AG don't you Greg?

Yes I do brew AG, though a bit more basic than most of the brewers on AHB. I think hdpe is fine for brewing if you bottle or keg within a month (or 2). For wine or cider at home you need glass or ss, because you store it longer. I mainly do wine and cider now because I can grow my own grapes and apples, growing barley is a bit harder at my place.

 

[MHB]

Given that a lot of what Greg.L has said about the permeability of plastics films, containers and lids is right (even the bullet dodged on nochill cubes) his comments still lead to the wrong conclusion.
You can get Acetaldehyde in a beer brewed in a stainless steel uni tank (CCV) where from the time the yeast is pitched to the time the beer is ready to serve there is going to be overpressure and no measurable oxygen ingress.
I think this shows conclusively that taste able amounts of Acetaldehyde can and I would argue are generally caused by poor brewing rather than oxygen uptake and the chemical conversion of alcohol to Acetaldehyde.
I personally doubt you can get enough Oxidisation of Alcohol to Acetaldehyde without a lot of other related faults being very obvious. True O2 uptake after the yeast is pitched is something you want to minimise but for the average home brewer its going to be far more important to make sure you have a big and healthy enough yeast pitch going into a well made wort and that the temperature of the ferment is well managed.
If you are using gladwrap I wouldnt stop, there are lots of more important issues that would need to be addressed before I worried about that. The trace amounts of O2 that can (and do) get into the wort will be quickly consumed by the yeast
Wine makers often have different points of view to brewers I think largely because they throw SO2 at everything with a wide mouthed shovel, something we as brewers just dont have the luxury of doing.
Mark

 

[Greg.L]

It may be possible to get residual acetaldehyde from the fermentation process, but it's not something I have experienced, and I doubt that it is common. It is very easy for ethanol to oxidise to acetaldehyde after fermentation has finished, something i have seen very often with wine and cider. You don't usually get other faults, though it is quite possible because o2 causes infections as well as oxidation.

If you are happy using gladwrap, then by all means continue. Personally I like to eliminate the chance of problems before they happen, rather than after, and that means a lid with a good solid seal.

brewers don't add so2 but yeast produce their own so2 naturally.

 

[drsmurto]

It may be possible to get residual acetaldehyde from the fermentation process, but it's not something I have experienced, and I doubt that it is common. It is very easy for ethanol to oxidise to acetaldehyde after fermentation has finished, something i have seen very often with wine and cider. You don't usually get other faults, though it is quite possible because o2 causes infections as well as oxidation.

If you are happy using gladwrap, then by all means continue. Personally I like to eliminate the chance of problems before they happen, rather than after, and that means a lid with a good solid seal.

brewers don't add so2 but yeast produce their own so2 naturally.

You get vastly more acetaldehyde in wine due to a set of complex redox cycles in which the polyphenols play a central role (along with transition metals such as Fe and Cu). The levels of polyphenols in wine, as far i my research tells me, is much, much higher than in beer. Without these redox cycles oxygen does nothing as molecular oxygen cannot react with organic compounds.

 

[pk.sax]

I've had had a beer brewed with gladwrap develop a slight film, this was at the end of a 4ish week ferment. The problem is that for the average time a homebrewer keeps it under gladwrap, there is a decent amount of CO2 coming out and then after that it takes time for enough oxygen to seep through the wrap (observational) to cause anything noticeable. with an HDPE lid, this will be a longer time but most home brewers don't keep it like that for so long anyway. Hence the common experience here of using gladwrap.
I personally ditched the wrap and use a blowoff tube now because of the bother the wrap creates with handling (I tears too easily) and moving fermenters.

Then again, some people have heaps of space in their sheds and don't need to move their fermenters ever so they don't have to care. Horses for golf courses.

 

[Greg.L]

The problem with all threads about taints and faults is you can't taste beer over the internet (or is there an app for that?). Descriptions are subjective and you really need to taste the beer and see the process to diagnose a fault. I have never tasted acetaldehyde in beer, and it's not a taint I would associate with beer. My advice is only general, how to improve your process to reduce the general chance of faults. I think that if you are getting acetaldehyde in beer you must be doing something very wrong, and since the poster was using gladwrap it seems like a good place to start. The general principal of excluding air whenever possible can't really be challenged (IMO).

 

[daemon]

I bottle condition, the yeast soak up the little bit of o2 in the bottles. I handle my beer/wine/cider as little as possible. The fact that some contact with air is inevitable when handling makes it more important to reduce air contact at other times, the effect tends to be cumulative.

So what would be the difference between o2 permeating the glad wrap vs o2 contained within bottles and kegs? I would have thought there'd be an order of magnitude in o2 concentration in a keg / bottle vs what can possibly enter a glad wrap barrier (especially since a fermenter has positive co2 production). I'm still fairly certain you're chasing the wrong cause here, especially since many experienced brewers use glad wrap without any Acetaldehyde problems.

The problem with all threads about taints and faults is you can't taste beer over the internet (or is there an app for that?). Descriptions are subjective and you really need to taste the beer and see the process to diagnose a fault. I have never tasted acetaldehyde in beer, and it's not a taint I would associate with beer. My advice is only general, how to improve your process to reduce the general chance of faults. I think that if you are getting acetaldehyde in beer you must be doing something very wrong, and since the poster was using gladwrap it seems like a good place to start. The general principal of excluding air whenever possible can't really be challenged (IMO).

Actually, many of us are in clubs that meet monthly to taste and judge beer, as well as general AHB meetups / case swaps. Faults (if they exist) are identified and generally then discussed with the brewer afterwards to help determine the cause and/or eliminate it in future brews. This is with experienced and professional brewers too, not just a few neighbours meeting to try the latest kit + sugar.

You think that's very wrong to get Acetaldehyde in a beer yet it's naturally produced by yeast but normally "cleaned up" by the yeast once fermentation has completed. If you're bottling then the time it takes for the secondary fermentation will be long enough to clean up most of the Acetaldehyde if it's been a healthy fermentation.

MHB has offered the best advice, check the health of your yeast, check the quantities you're pitching and ensure you manage the fermentation process well (time + temp). Also allow the beer to condition for longer on the original yeast to allow the yeast to cleanup the Acetaldehyde. Personally I ferment for 7 days, let it sit for an additional 3 days to allow the yeast to cleanup and then cold condition for up to 7 days before kegging. Many others have different timings (depending on style + personal preferences etc), so figure out what works for you.

 

[OneEye]

Thanks again for all the replies guys. I could be wrong and what I've got here isn't acetaldehyde (although it is super green) at the same time it is sour too, and seems to be getting worse. Could be an infection of some kind? This will be the 3rd batch that's exhibited the same signs. The first was an extract porter recipe (15L pitched unhydrated US05), and on the same brew day I made a 15L CPA BIAB (cooled with my plate chiller and pitched a 1L starter of 1056 that I made the day before) The third batch was a DrSmurto Golden Ale, again 15L BIAB with a 1L starter of 1056.
2 different fermenters in total. The extract never touched my urn or chiller. The only thing they all had in common was being in the same temp controlled fermentation space (an old bathroom vanity than I've insulated and installed a flood light into) all with glad wrap lids. 14 days each (give or take a few days)

I'm currently soaking the fermenters in PBW and I might pick up a FWK and try and ferment that into something drinkable to fill my little kegs up.

Edit: It's just weird that this is popping its head up after half a dozen successful brews so far, using pretty much the same equipment/process

 

[///]

Some of the best beer I've ever had, and the best brewery I have ever been too (and I go to alot of them) ... open fermentation and lots of air ... boyah Anchor Brewing.

Open air ferments have been done for hundreds of years, may the practice continue ....

 

[daemon]

The fact that it's also got a sour taste isn't a good sign, normally this a bacterial infection. Did you notice any problems with the fermentation, eg a film over the top of the krausen? Have a look at the Infection Photo thread for examples: http://www.aussiehomebrewer.com/forum/inde...showtopic=51830

It could be acetic acid bacteria if oxygen has re-entered the beer, how careful are you when transferring to the keg?

 

[manticle]

The problem with all threads about taints and faults is you can't taste beer over the internet (or is there an app for that?). Descriptions are subjective and you really need to taste the beer and see the process to diagnose a fault. I have never tasted acetaldehyde in beer, and it's not a taint I would associate with beer. My advice is only general, how to improve your process to reduce the general chance of faults. I think that if you are getting acetaldehyde in beer you must be doing something very wrong, and since the poster was using gladwrap it seems like a good place to start. The general principal of excluding air whenever possible can't really be challenged (IMO).

All that's well and good Greg but you were very specific and assured about your reasoning for a fault you admit you can't taste over the net and admit you have never tasted in beer (doesn't mean it doesn't exist) and when questioned, suggested no-one else had ever tasted a sample of acetaldehyde.

I think you were off base with the way you approached this. You have a good knowledge base and good experience that can help people out but there's a lot of others with a very decent knowledge base and experience here too - many comparable to yours. Casting aspersions on their experience won't make people want to listen to you, even if and when you are correct.

 

[kirem]

You get vastly more acetaldehyde in wine due to a set of complex redox cycles in which the polyphenols play a central role (along with transition metals such as Fe and Cu). The levels of polyphenols in wine, as far i my research tells me, is much, much higher than in beer. Without these redox cycles oxygen does nothing as molecular oxygen cannot react with organic compounds.

WINE NERD

 

[Screwtop]

WINE NERD

Yeah, bloody wine nerds :lol:

Screwy

 

[Greg.L]

I've posted a bit on this thread because some people think glad wrap is a good barrier against oxygen getting in beer. The fact is that it's not. I understand the confusion because it seems counter-intuitive that oxygen can get in when it is full of co2, but it can and will. There isn't a good reason to use glad wrap, a tight lid with an airlock keeps oxygen out much better.

I also think that because beer is so tolerant of rough treatment people get a bit relaxed about good brewery practise. Talk about open ferments and such encourages people to think it's ok to get a bit of air in there. If you keep a tight lid on and don't handle the beer too much the chances of having a problem are pretty remote.

 

[drsmurto]

WINE NERD

B)

 

[Nick JD]

Why is kit beer often acetylaldehydey? Is it the sucrose?

 

[drsmurto]

Breweries and wineries may open ferment but I doubt many fermenters remain open when the fermentation slows down/stops.

 

[Acasta]

Well after sifting through the great debate in this thread, I'm wondering if we can get some good discussion on the topic of how to get rid of Acetaldehyde?
Granted that it may be caused by oxygenation or poor yeast conditions.

I'm not sure what has caused the Acetaldehyde in my brew. I pitched it onto the cake of a previous beer (so enough yeast cells) and left it there for 2 weeks at 18-20deg (which should have been long enough for yeast to finish and clean up?). I then chilled it, after 2 days added gelatine and 2 days after that kegged and force carbed.
The fresh fruit/green taste didn't really show up until recently (few days in the keg), I'm quite sure it wasn't there in the fermenter early on, but I didn't sample from after 1.5 weeks from pitching to after kegging.

What are some ways of getting it to clean up? It was chilled in the fridge, so I've taken the keg out and left it in the garage to warm up and hopefully help the flavours balance out a bit quicker.

As I was reading this thread I found this, which moosebeer had come accross. Anyone tried it? I'm thinking of attempting to burp it a bit for a few days if that might help.

I've also had a beer, a pils using S189 that never got rid of this flavour. 4 weeks in fermenter and 4 weeks in keg and still had that flavour.

"Either way, I barely noticed this when transfering to the keg and thought it was mild and would lager-out. 3 weeks later, I took a sample and definitely decided I couldnt drink a keg of the stuff. So I started doing some research. It turns out that acetylaldehyde is very volatile, and the fact that the keg was already carbed could be a huge benefit, as the escaping CO2 at warmer temps would bring the acetylaldehyde right with it.

I took the keg out of the kegerator, and burped the pressure relief valve every day or so for 5 days now. Additionally, I took some yeast cake, added about 8oz of wort to it, let it start fermenting for about 24h and pitched that.