Acetaldehyde After 4 Days Lagering

[ozpowell]

Hi All,

I'm doing an Oktoberfest using the "primary -> crash chill -> transfer to keg" (ie. no secondary) method. OG was 1052 chilled to 10*C, pitched 1.75L Wyeast 2633 starter. Fermented for 10 days @10*C, then 2 day d-rest @ 16*C, then reduced temperature 3*C per day to 0*C - total 2.5 weeks in primary. FG was 1013.

I then filtered to keg and attached the CO2 to force carbonate (11.5psi @ 3*C). At that point, the beer tasted fine - very clean. Four days later (yesterday), I tasted a sample from the keg. Obviously not fully carbonated yet, but there is a distinct Acetaldehyde aroma (ie. green apple smell) which definitely wasn't there before.

I've done some researching and some information I've found indicates that this is normal and will reduce over time (ie. Palmer "How to Brew"), while other information indicates that it is due to oxidation and the beer is ruined. I guess I could have accidently oxidized my beer when filtering (there was air in the filter cartridge for about the first 20 seconds of the filter, but was airtight from then on). Note that the receiving keg was purged with CO2 prior to filtering.

Anyone out there able to allay my fears, or am I hosed????

TIA,
Michael.

 

[Screwtop]

Hi All,

I'm doing an Oktoberfest using the "primary -> crash chill -> transfer to keg" (ie. no secondary) method. OG was 1052 chilled to 10*C, pitched 1.75L Wyeast 2633 starter. Fermented for 10 days @10*C, then 2 day d-rest @ 16*C, then reduced temperature 3*C per day to 0*C - total 2.5 weeks in primary. FG was 1013.

I then filtered to keg and attached the CO2 to force carbonate (11.5psi @ 3*C). At that point, the beer tasted fine - very clean. Four days later (yesterday), I tasted a sample from the keg. Obviously not fully carbonated yet, but there is a distinct Acetaldehyde aroma (ie. green apple smell) which definitely wasn't there before.

I've done some researching and some information I've found indicates that this is normal and will reduce over time (ie. Palmer "How to Brew"), while other information indicates that it is due to oxidation and the beer is ruined. I guess I could have accidently oxidized my beer when filtering (there was air in the filter cartridge for about the first 20 seconds of the filter, but was airtight from then on). Note that the receiving keg was purged with CO2 prior to filtering.

Anyone out there able to allay my fears, or am I hosed????

TIA,
Michael.

Experienced pretty much the same thing in a couple of recent lagers. Couple of questions if you don't mind Mike. 1. What malt bill. 2. Did you soak your filter cartridge in bleach to clean it.

Screwy

 

[ozpowell]

Experienced pretty much the same thing in a couple of recent lagers. Couple of questions if you don't mind Mike. 1. What malt bill. 2. Did you soak your filter cartridge in bleach to clean it.

Screwy

Hey Screwy,

1. Malt bill (for 25L batch): base malt 5Kg Weyermann Bohemian Pilsner, 250g Burston Caramalt, 250g Weyermann Caramunich I, 250g Weyermann Caramunich III, 150g Weyermann Melanoidin. Grains were double decoction mashed.

2. Soaked the cartridge in nappysan - not bleach.

You mentioned that you have had the same issue recently - did extended lagering reduce the Acetaldehyde aroma?

Thanks,
Michael.

 

[Darren]

Hey OzPowell,

I dont think you are alone in this caper. I have tasted many an Octoberfest with the "appley" flavour including my own. The flavour will dissipate a little but not completely.

One thing to keep in mind when doing a big lager is the yeast. If it aint pumping when you pitch it it wont make it all the way. 10 day ferment is not long enough either, needs 3-4 weeks minimum at 10C. I suspect that alot of that apple came from raising the ferment temps before she was finished.

On the malt, did you have munichII in there by any chance?

I doubt it is the filter as this apple you speak of is in most HB strong dark lagers I have tasted.

cheers

Darren

EDIT: The filter will have removed any yeast that would have been capable of cleaning the apple up

 

[goatherder]

I think Darren is on the right track with the yeast. I normally do my lagers for 3 weeks at 10c. The few times I've used 2633 I haven't had a problem with acetaldehyde.

Another contributer may be the amount of yeast you've pitched. Assuming you've got a 20something litre batch, 1.75 litres of starter won't nearly be enough at 10 degrees. I reckon you'll need at least twice that. Check out the pitching rate calc at mrmalty.com, it's not bad as a starting point for pitch rates.

 

[ozpowell]

Darren, GH,

Thanks for the feedback. A bit more info:

- Starter - I used the following Wyeast pitchrate calculator to determine my starter size (note I used a stirplate). I'm pretty sure the starter was large enough. The calculator estimated around 12M cells/ml and the brew started firing within 24 hours of pitching at 10*C. High krausen (about 2 inches thick) by day 3. Having said that, I'll probably go for a slightly larger starter next time just in case anyway...

- Length of ferment - I didn't start the d-rest until the gravity hit 1026 (day 10). Two-thirds the way through the ferment. FG at time of transfer to keg was 1013 which was my estimated FG, so I don't think there was too much left.

Darren - no Munich II - why do you ask?

Guess I'll just wait a few weeks and see how it goes...

Thanks again for the feedback.

Cheers,
Michael.

 

[Darren]

Ozpowell,

Are you sure it tastes like "green apple" which would be sour or just like "apple"?

1.026 is far too early to pull a lager from the fridge. That is where the flavour has come from. Dont do a diacetyl rest unless your beer needs it. Diacetyl is one brew compound that would be cleaned up easily. Small amounts of diacetyl dissipate over time.

Not sure about the Munich II, just trying to figure out why these large dark lagers taste like this.

cheers

Darren

 

[goatherder]

- Starter - I used the following Wyeast pitchrate calculator to determine my starter size (note I used a stirplate). I'm pretty sure the starter was large enough. The calculator estimated around 12M cells/ml and the brew started firing within 24 hours of pitching at 10*C. High krausen (about 2 inches thick) by day 3. Having said that, I'll probably go for a slightly larger starter next time just in case anyway...

Fair enough, I can see why you went for that size starter. I subscribe to the school of thought which says that a lager should have twice the pitch rate of an ale - the Wyeast calculator doesn't make this distinction. A rule of thumb which I use is 1M cells per ml per degree plato of the wort for an ale, twice that for a lager. For your beer that would translate to 26M cells/ml, about twice as much starter as you had. It may be overkill but I find it works really well for me.

 

[Gulf Brewery]

Hi

I have done a few Oktoberfests and the acetaldehyde has always been due to yeast stress - either underpitching or poor yeast. Goatherder is on the money with pitching twice as much. I also subscribe to the White Labs method - pitch warm and chill before anaerobic fermentation starts.

Cheers
Pedro

 

[ozpowell]

Update. 7 days lagering @ 3*C - acetaldehyde aroma is diminished quite substantially. Still present but noticably decreased. Will try it again next week.

Cheers,
Michael.

 

[Screwtop]

Hey Screwy,

1. Malt bill (for 25L batch): base malt 5Kg Weyermann Bohemian Pilsner, 250g Burston Caramalt, 250g Weyermann Caramunich I, 250g Weyermann Caramunich III, 150g Weyermann Melanoidin. Grains were double decoction mashed.

2. Soaked the cartridge in nappysan - not bleach.

You mentioned that you have had the same issue recently - did extended lagering reduce the Acetaldehyde aroma?

Thanks,
Michael.

Trying to get to the bottom of this: Green apple aroma in all lagers/ales using Wey Pils. The batch I mentioned was filtered at about 10 days straight from primary to Keg. As Darren pointed out filtering out the yeast meant it would have less yeast to do the cleaning up. This is what has happened, it has taken a number of weeks to reduce the aroma, but the flavour still remains, just. Two lager batches since were left for 4 weeks in primary to overcome the problem, one has no green apple aroma and the other still has some. Both of these were 50/50 Wey Pils and Galaxy. A recent Kolsch using 100 Wey Pils had the same aroma, it was also filtered so has taken a long time to loose the aroma in the keg. All of the lagers were fermented using 23g of rehydrated S-189.

Screwy

 

[mfdes]

2. Soaked the cartridge in nappysan - not bleach.

Off topic, but nappysan is a cleaner, not a sanitiser. You will need to rinse it thoroughly and will undo any sanitation it may have carried out anyway.

MFS

 

[Online Brewing Supplies]

Trying to get to the bottom of this: Green apple aroma in all lagers/ales using Wey Pils. The batch I mentioned was filtered at about 10 days straight from primary to Keg. As Darren pointed out filtering out the yeast meant it would have less yeast to do the cleaning up. This is what has happened, it has taken a number of weeks to reduce the aroma, but the flavour still remains, just. Two lager batches since were left for 4 weeks in primary to overcome the problem, one has no green apple aroma and the other still has some. Both of these were 50/50 Wey Pils and Galaxy. A recent Kolsch using 100 Wey Pils had the same aroma, it was also filtered so has taken a long time to loose the aroma in the keg. All of the lagers were fermented using 23g of rehydrated S-189.

Screwy

Sounds like you got a problem there.Will not be the grain.
GB

 

[Screwtop]

Sounds like you got a problem there.Will not be the grain.
GB

Thanks GB, thought maybe I was hyper sensitive to the euro pils aroma, but a commercial brewer (micro) agreed it is Acetaldehyde. Figure the reduction due to ageing would tend to indicate fermentation issues. However something very confusing to me is that the amount of aroma is directly resultant upon the amount of WeyPils. To have it appear in top and bottom fermenting yeasts is weird and would indicate infection. Very confusing!!

 

[Online Brewing Supplies]

Thanks GB, thought maybe I was hyper sensitive to the euro pils aroma, but a commercial brewer (micro) agreed it is Acetaldehyde. Figure the reduction due to ageing would tend to indicate fermentation issues. However something very confusing to me is that the amount of aroma is directly resultant upon the amount of WeyPils. To have it appear in top and bottom fermenting yeasts is weird and would indicate infection. Very confusing!!

I would be also looking at Ethyl Hexanoate (similar profile but a little more fruity than green apples) as well as a cause.This could turn up in all beers and is usually an indication of underpitching . But this doesnt explain fully why its turned up in all beers unless infection has got in to the system.A microscope real does help here even if you cant identify the beast you will certainly know its not a normal yeast cell.
GB

 

[matti]

I recall drinking Aussie commercial lager about 10-15 years ago and notice apple aroma/flavour.
It was very prevalent and I was surprised that no one else could detect it.
Not as bad as Blue tounge lager though LOL
My memory is a bit dodgy so I cannot remember which brew it was. I recjkon it was either Hahn, Toheys dry or one of those Tasmanian drops.

I suppose the BIG boys brew regime doesn't allow the yeast to clean up all that Acetaldehyde!?

I agree with GB

 

[ozpowell]

Off topic, but nappysan is a cleaner, not a sanitiser. You will need to rinse it thoroughly and will undo any sanitation it may have carried out anyway.

MFS

Sorry - should have mentioned that it is sanitized in star-san solution also I use the sodium percarb just to clean the cartridge after filtering.

Cheers,
Michael.

 

[mfdes]

Mate, no need to be sorry, I wasn't telling you off

Just mentioning in case people got confused.

MFS

 

[Screwtop]

I would be also looking at Ethyl Hexanoate (similar profile but a little more fruity than green apples) as well as a cause.This could turn up in all beers and is usually an indication of underpitching . But this doesnt explain fully why its turned up in all beers unless infection has got in to the system.A microscope real does help here even if you cant identify the beast you will certainly know its not a normal yeast cell.
GB

GB, thanks for the tip, thought Ethyl Hexanoate was more a product of ageing. Have an old scope somewhere, haven't looked at yeast through one in more than 30 years.

Screwy