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General Category => Yeast and Fermentation => Topic started by: Iliff Ave Brewhouse on September 14, 2017, 04:49:37 AM

Title: Off flavors from stressed lager yeast
Post by: Iliff Ave Brewhouse on September 14, 2017, 04:49:37 AM
Any resources regarding possible off flavors for beers produced from stressed lager yeast? I underpitch and every once in a while get a strange flavor that i assume is related to this bad practice.
Title: Re: Off flavors from stressed lager yeast
Post by: dmtaylor on September 14, 2017, 04:53:43 AM
I've gotten acetaldehyde (green apple) flavor from an unhealthy lager pitch.

And now my current W-34/70 lager tastes fruity because I was dumb enough to ferment it at 65 F because Brulosophy has proven numerous times that people can't tell the difference -- well I can.  So yeah... stuff can happen.

Acetaldehyde is one of the main ones that is in fact caused by stressed yeast.

Diacetyl (popcorn butter) is also very common but is not caused by stress, but just regular yeast metabolism.  Eventually they clean it up but it takes time.
Title: Re: Off flavors from stressed lager yeast
Post by: Iliff Ave Brewhouse on September 14, 2017, 05:10:02 AM
I mostly use 34/70 and it pops up about once a year. It's almost like a mix between oxidation and gym sock in flavor and aroma. The last batch with this problem seemed to improve dramatically after a couple of months in the keg. I also seem to be a lot more sensitive to it than most and sometimes pick it up in certain commercial beers that are lagers. The beer did seem to lag more than most but attenuated well.
Title: Re: Off flavors from stressed lager yeast
Post by: brewinhard on September 14, 2017, 02:02:15 PM
Any resources regarding possible off flavors for beers produced from stressed lager yeast? I underpitch and every once in a while get a strange flavor that i assume is related to this bad practice.

When I have taken a lager strain out too many generations (at least for my brewery) I have observed production of strange esters (strawberry like, but faint) even fermented and pitched as low as 46F. I have also gotten some excess vegetal/slight medicinal notes which could very well be from underpitching/yeast handling. 
Title: Re: Off flavors from stressed lager yeast
Post by: 802Chris on September 14, 2017, 02:57:50 PM
I've gotten acetaldehyde (green apple) flavor from an unhealthy lager pitch.

And now my current W-34/70 lager tastes fruity because I was dumb enough to ferment it at 65 F because Brulosophy has proven numerous times that people can't tell the difference -- well I can.  So yeah... stuff can happen.

Acetaldehyde is one of the main ones that is in fact caused by stressed yeast.

Diacetyl (popcorn butter) is also very common but is not caused by stress, but just regular yeast metabolism.  Eventually they clean it up but it takes time.

I recently underpitched a lager with 34/70 (single pack) It is loaded with green apple sourness I am attributing to acetaldehyde. won't do that again...
Title: Re: Off flavors from stressed lager yeast
Post by: zwiller on September 14, 2017, 07:32:40 PM
I am not aware of any lager off flavor chart or info but my personal opinion is that ales throw "hot" or "alcoholish" when stressed and lagers throw "fruit" but much less compared to an ale yeast.  The 2x I did 3470 warm I made NGP and it is possible all the hoppiness hid any fault, but I do not plan to change.  Those were single pack hydrated for 5G.

I don't obsess about cell counts and only use a practical approach.  In the past, I pretty much underpitched constantly but still made great beer.  Any off flavor was very minor/probably only noticed by a BJCP.  That being said, I have always been anal about pH and perhaps that has always saved my a$$. ;D
Title: Re: Off flavors from stressed lager yeast
Post by: erockrph on September 15, 2017, 01:58:25 PM
Acetaldehyde is one of the intermediate steps in the production of ethanol during fermentation. Normally the yeast cleans this up well before the end of fermentation. I think acetaldehyde is usually the byproduct of either a fermentation that is stopped early (cold crash too soon or something of that nature), or a big overpitch that blows through all the sugar really quick and flocs out before it finished cleaning up.

I think that apple off-flavors are probably more likely to be from esters or fusels than acetaldehyde. I realize that's a bit of a semantic argument, since these are all similar off-flavors caused by fermentation issues. But I don't think that acetaldehyde is as big of a boogeyman as it is often made out to be.
Title: Re: Off flavors from stressed lager yeast
Post by: denny on September 15, 2017, 02:25:04 PM
Acetaldehyde is one of the intermediate steps in the production of ethanol during fermentation. Normally the yeast cleans this up well before the end of fermentation. I think acetaldehyde is usually the byproduct of either a fermentation that is stopped early (cold crash too soon or something of that nature), or a big overpitch that blows through all the sugar really quick and flocs out before it finished cleaning up.

I think that apple off-flavors are probably more likely to be from esters or fusels than acetaldehyde. I realize that's a bit of a semantic argument, since these are all similar off-flavors caused by fermentation issues. But I don't think that acetaldehyde is as big of a boogeyman as it is often made out to be.

I agree with ya.
Title: Re: Off flavors from stressed lager yeast
Post by: Iliff Ave Brewhouse on September 15, 2017, 02:46:52 PM
Thanks all. Definitely not acetaldehyde here. I guess I will keep guessing.
Title: Re: Off flavors from stressed lager yeast
Post by: mabrungard on September 15, 2017, 03:10:56 PM
And now my current W-34/70 lager tastes fruity because I was dumb enough to ferment it at 65 F because Brulosophy has proven numerous times that people can't tell the difference -- well I can.  So yeah... stuff can happen.

Bless those folks that do these trials, but I do question their results due to exactly this point. Untrained and insensitive drinkers that probably only can tell that its 'beer', aren't well suited to discerning the minor impacts that those testing trials impart on the beer. In addition, without training and sensitizing, most drinkers would overlook these minor flaws that the trials MIGHT have produced.

My understanding of proper flavor testing by major breweries and testing services (like Siebel), is that they train and sensitize their tasting panels to recognize the flaw characteristics before the conduct their blind triangle testing series. In my opinion, the trials done by the homebrewer groups are innately flawed because of this lack of training.

Again, I commend those homebrew groups for their efforts, but they do need to improve their assessment methods in order to make any of their results worth anything.
Title: Re: Off flavors from stressed lager yeast
Post by: Stevie on September 15, 2017, 03:17:49 PM
Acetaldehyde is also very distinctive in flavor once you know way to look for. Apple esters are different.
Title: Re: Off flavors from stressed lager yeast
Post by: erockrph on September 15, 2017, 03:30:50 PM
Acetaldehyde is also very distinctive in flavor once you know way to look for. Apple esters are different.

And it's not green apple Jolly Rancher like many claim, at least not to me. It's more like that fruity/dirty/solventy aroma of drying paint.
Title: Re: Off flavors from stressed lager yeast
Post by: ynotbrusum on September 15, 2017, 06:56:13 PM
I have noticed that a few people can pick up a very faint lemon character in light lagers (especially a Helles) when fermented with 34/70.  I went to S-189 for dry lager yeast because of that and don't seem to have any problems (though some might say it is too clean for their tastes?)  I pitch 3 packs (re-hydrated) in a 10 gallon batch fermenting at 46F without any issue.
Title: Re: Off flavors from stressed lager yeast
Post by: Frankenbrew on September 15, 2017, 11:42:05 PM
I love S-189! I'm not a fan of 34/70. I have used both of them with limited temperature control and have not been happy with the results of 34/70. S-189 is much more forgiving and much cleaner, which is what I'm looking for in a lager.
Title: Re: Off flavors from stressed lager yeast
Post by: The Beerery on September 16, 2017, 12:08:17 AM
I am one who can pick up lemon in 34/70 and hate it with a passion.  Can't beat the sulfury German strains for lagers. 


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Title: Re: Off flavors from stressed lager yeast
Post by: The Beerery on September 16, 2017, 12:09:01 AM
I am one who can pick up lemon in 34/70 and hate it with a passion.  Can't beat the sulfury German strains for lagers. 


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Title: Re: Off flavors from stressed lager yeast
Post by: Iliff Ave Brewhouse on September 16, 2017, 02:22:56 AM
Sorry. I was referring to the OP

Edit- looks like my previous post didn't go through. Lemon is not the issue this time. I get that 34/70 sucks but i don't think my problem is related to using this yeast versus a different yeast.
Title: Re: Off flavors from stressed lager yeast
Post by: hopfenundmalz on September 16, 2017, 07:08:43 AM
Acetaldehyde is also very distinctive in flavor once you know way to look for. Apple esters are different.

And it's not green apple Jolly Rancher like many claim, at least not to me. It's more like that fruity/dirty/solventy aroma of drying paint.
When I sat in an off flavor class last year, the acetaldehyde spike really made the connection to green Jolly Rancher for me. At the level of the spiked beer that was what I got. At lower levels, it may have been different. We are all different, so it worked for me, and that association may not work for you.
Title: Re: Off flavors from stressed lager yeast
Post by: majorvices on September 16, 2017, 01:17:44 PM
I am one who can pick up lemon in 34/70 and hate it with a passion.  Can't beat the sulfury German strains for lagers. 


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I have also picked up the lemon ester. I use 34/70 in emergency cases. But I will say most people don't pick it up.
Title: Re: Off flavors from stressed lager yeast
Post by: majorvices on September 16, 2017, 01:20:54 PM
Sorry. I was referring to the OP

Edit- looks like my previous post didn't go through. Lemon is not the issue this time. I get that 34/70 sucks but i don't think my problem is related to using this yeast versus a different yeast.

I don't think 34/70 sucks. I think it is a viable alternative to 2124/830. But I have picked up the lemon thing. I think the beer is still good and the ester is faint. It also fades over a few weeks.
Title: Re: Off flavors from stressed lager yeast
Post by: dmtaylor on September 16, 2017, 02:09:42 PM
I don't hate W-34/70.  I just do NOT love it like I wish I could.  I will not be using it anymore for this precise reason -- I do NOT love it, and I DO love many other lager strains.
Title: Re: Off flavors from stressed lager yeast
Post by: erockrph on September 16, 2017, 05:13:32 PM
Sorry. I was referring to the OP

Edit- looks like my previous post didn't go through. Lemon is not the issue this time. I get that 34/70 sucks but i don't think my problem is related to using this yeast versus a different yeast.

I don't think 34/70 sucks. I think it is a viable alternative to 2124/830. But I have picked up the lemon thing. I think the beer is still good and the ester is faint. It also fades over a few weeks.
Interesting. I've never noticed the lemon thing, but I use Sterling for my lagers and could have easily written it off as hop character.

FWIW, I think 34/70 is the ultimate jack of all trades yeast. It can make a passable version of just about any lager or non-yeast forward ale, and it is very forgiving with fermentation temperatures. That said, it is not my first choice for any style unless I need to ferment a lager near 60F.

S189 is a better choice for a clean, dry lager yeast, but it is way more temperature sensitive. It can throw fusels as low as the mid 50s. And I still prefer liquid yeast when I want that touch of sulfur for a German lager style.

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Title: Re: Off flavors from stressed lager yeast
Post by: TheDrunkenMaster on September 18, 2017, 01:22:19 PM
I always pitch my North East, heavy hop schedule IPAs hot because I love the yeasty, estery flavours. I do pitch a massive starter though.

I pitched the last one at 167 degrees. It was awesome and this coming from someone who has been a beer buyer for China for a number of years.

Title: Re: Off flavors from stressed lager yeast
Post by: Stevie on September 18, 2017, 01:45:00 PM
Absolutely now way you pitch at 167 and have that yeast survive. That's 10-12 second pasteurization temp.
Title: Re: Off flavors from stressed lager yeast
Post by: TheDrunkenMaster on September 18, 2017, 01:51:10 PM
After pitch it went straight in the fridge at 67.

Fermented happily there during primary and racked off to carboy for a few weeks before kegging.

Juicy af.
Title: Re: Off flavors from stressed lager yeast
Post by: dmtaylor on September 18, 2017, 02:08:26 PM
Who needs yeast and alcohol when you can just enjoy juicy hop soup!?   ;D
Title: Re: Off flavors from stressed lager yeast
Post by: Stevie on September 18, 2017, 02:11:36 PM
After pitch it went straight in the fridge at 67.

Fermented happily there during primary and racked off to carboy for a few weeks before kegging.

Juicy af.
Again, absolutely no way their is any truth to this story.
Title: Re: Off flavors from stressed lager yeast
Post by: TheDrunkenMaster on September 18, 2017, 02:12:58 PM
Y'all should try it instead of sitting there saying "I know better".

I don't just experiment but it is, as it has always been, the key to progress.

Title: Re: Off flavors from stressed lager yeast
Post by: Stevie on September 18, 2017, 02:15:08 PM
(https://uploads.tapatalk-cdn.com/20170918/cdf8c5dc5276ebebd442720322b475d1.jpg)
Title: Re: Off flavors from stressed lager yeast
Post by: TheDrunkenMaster on September 18, 2017, 02:24:45 PM
Oh look an old meme.

So tell me, what is wrong with me commenting with my personal experiences in the hopes of provoking a constructive discussion around fermentation temps? You don't like change? I've disrupted the forum hierarchy by refusing to defer to presumed superiors?

Yes, that temperature is very high and according to the science, the yeast should have died. But they didn't and I got something wonderful out of it. Tell me where the negative is in that?



Title: Re: Off flavors from stressed lager yeast
Post by: dmtaylor on September 18, 2017, 03:33:18 PM
(https://farm5.staticflickr.com/4379/36492364553_fc4529b634_o.png)

Sorry, I just couldn't resist.   ;D

If he says he pitches at 167 F and gets good results, and we haven't tried it, truly, who are we to doubt.  I doubt that 100% of the yeast is instantly killed.  Some of them may be mutants, survival of the fittest, and just start working all the faster at the high temps.
Title: Re: Off flavors from stressed lager yeast
Post by: bayareabrewer on September 18, 2017, 06:41:36 PM
just seems to contradict this

http://www.engineeringtoolbox.com/pasteurization-methods-temperatures-d_1642.html
Title: Re: Off flavors from stressed lager yeast
Post by: Stevie on September 18, 2017, 07:32:02 PM
just seems to contradict this

http://www.engineeringtoolbox.com/pasteurization-methods-temperatures-d_1642.html
And every middle school biology book from the past hundred years.
Title: Re: Off flavors from stressed lager yeast
Post by: bayareabrewer on September 18, 2017, 08:14:07 PM
I know of many homebrewers and some breweries that are pasteurizing their wort prior to lacto souring using temps somewhere in the 165 degree range and none report yeast contamination. If you had a successful fermentation, it was probably from something besides the yeast you pitched.
Title: Re: Off flavors from stressed lager yeast
Post by: tommymorris on September 18, 2017, 08:33:43 PM
...or a broken thermometer.
Title: Re: Off flavors from stressed lager yeast
Post by: dmtaylor on September 18, 2017, 08:34:45 PM
...If you had a successful fermentation, it was probably from something besides the yeast you pitched.

That is an even more likely theory.

But, no need to respond further.  The troll is gone, and the bait very well consumed.
Title: Re: Off flavors from stressed lager yeast
Post by: Stevie on September 18, 2017, 09:14:56 PM
Even if it is bait, not disagreeing and leaving it could cause a new brewer to jack up an expensive batch because this wad was trolling.
Title: Re: Off flavors from stressed lager yeast
Post by: charles1968 on September 20, 2017, 12:15:25 PM
Pretty sure he meant 67, as in his second post, and 167 is a typo!
Title: Re: Off flavors from stressed lager yeast
Post by: Andor on September 20, 2017, 02:05:01 PM
I mostly use 34/70 and it pops up about once a year. It's almost like a mix between oxidation and gym sock in flavor and aroma. The last batch with this problem seemed to improve dramatically after a couple of months in the keg. I also seem to be a lot more sensitive to it than most and sometimes pick it up in certain commercial beers that are lagers. The beer did seem to lag more than most but attenuated well.

I wonder if there is variability in the quality of 34/70. I noticed a weird flavor sort of tart/caramel in my last batch I thought was some sort of mild infection. The identical recipe fermented exactly the same a few months ago didn't have the flavor.
Title: Re: Off flavors from stressed lager yeast
Post by: dmtaylor on September 20, 2017, 02:14:26 PM
I wonder if there is variability in the quality of 34/70. I noticed a weird flavor sort of tart/caramel in my last batch I thought was some sort of mild infection. The identical recipe fermented exactly the same a few months ago didn't have the flavor.

The very same thing just happened to me.  However, the yeast was like 4 years old so this *could* be my own fault too.