Autolysis.

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I have one beer in particular that has been sitting for over 2 years. You can see the precipitate in the bottom of the bottle. There is no noticeable flavor that I can detect from Yeast Autolysis. In fact, this brings up the question of beer that has been "refermented in the bottle" and is given a drink by date of like 7 years or something. I agree that Autolysis is indeed occuring, but I think the reality of it is that you either have to have a huge cake of yeast that goes bad and is enough to influence the flavor in a batch or you do something really wrong.
 
From what I'm reading (early days yet) I'm concluding that getting beer of the yeast ASAP is not necessary as far as off flavours from Autolysis is concerned and brewers shouldn't worry about 10+ days and shouldn't be overly worried about many weeks and even months.
 
I agree, Orfy.

I had a five gallon batch of edwort's pale ale that clogged and subsequently blewoff my blowoff tube when I was on vacation once - and returned to it five days later thinking it must be ruined. I sanitized and put the blowoff tube back on and forgot about it, focusing my efforts on brews I had more faith in.

I finally got around to kegging it after 3 months of it sitting on its yeast cake in the primary. I tasted it -- and it was wonderful. No trace of autolysis.
:ban:
 
Orfy said:
From what I'm reading (early days yet) I'm concluding that getting beer of the yeast ASAP is not necessary as far as off flavours from Autolysis is concerned and brewers shouldn't worry about 10+ days and shouldn't be overly worried about many weeks and even months.
Click to expand...

I think the key here is off flavors. Just because there aren't strong off flavors produced from keeping a beer in primary a long time, that doesn't rule out that, as the yeast are breaking down, they are in fact releasing compounds that influence the taste. I think the resulting flavor is much more subtle than is commonly believed, except for where there is a major problem. Depending on the beer style this may be more or less of an issue. In many of the beers style I brew I don't want a subtle yeasty flavor. I believe this is the true taste of yeast autolysis. If autolysis and the flavors it produces are widely accepted in the wine making circles, I find it hard to believe the same is not occuring in beer brewing
 
I just got a response from Greg D at Wyeast.

Here was my original email:
I am wondering if you could give some general information on yeast
autolysis as it pertains to the average homebrewer. We are having a
general discussion on the topic at the forum I frequent
(homebrewtalk.com).

My biggest question is if you pitch at correct rates by either
activating a newer package or making a starter, when does autolysis
become a problem? Is it a bogeyman for the average homebrewer?

I have started to not use a secondary vessel for most of my brews per
Jamil Zainasheff. I have left a beer in the primary on the yeast cake
for a month with no problems. I've also left a cider in a primary for 4
months. Is autolysis more likely to happen with stressed yeast or
certain strains? Or, is it just a time factor.

Finally, is autolysis something homebrewers need to worry about in the
bottle? Although I have not done it myself, I know homebrewers who have
aged beer for at least a year in the bottle with no perceived notes of
autolysis.
Click to expand...

Here is his response
Hi Ed,

Thank you for the email. Sorry to take so long in getting back to you.
I received a similar question at the same time as yours (I assume in
regards to the same discussion), so this email will be copied to another
brewer.

Eukaryotic apoptosis (programmed cell death) is still a very active
field of research mostly within animal systems. The current research
continues to shed light on the function of yeast aging, senescence, and
autolysis.

That being said, yeast autolysis has long been studied by the brewing
industry because of it's detrimental affects on the flavor and
appearance of beer. Autolysis is caused by the action of intracellular
hydrolytic enzymes including proteinases and glucanases. Factors
including , available food source (conditions of starvation), yeast
health (stressed or low viability) temperature (higher), alcohol
concentration (higher), osmotic pressure (higher), and strain selection
all contribute to the onset of autolysis. However for most beers, these
conditions are fairly standard and you should expect similar levels of
autolysis. Therefore, cell density (amount of yeast in beer able to
autolyze) and time become the most important factors in controlling or
minimizing autolysis.

Generally, good yeast handling and fermentation practices eliminate any
problems associated with autolysis. However, as time (yeast in contact
with beer) increases, autolysis will set in. The rate will of autolysis
will depend on the above mentioned factors (temperature, alcohol
concentration, etc.) but in most situations, finished beer can sit in
the primary for a couple of weeks before it becomes detectable. An
increase in pH indicates autolysis is occurring.

Autolysis is generally not a concern with bottle conditioning because
the cell density is at a very low level (5-10E 5 cells per ml. versus
30-100E6 in the fermenter).

I hope that this helps.

Cheers,

Greg
Click to expand...
 
Thanks for the emails.

but in most situations, finished beer can sit in
the primary for a couple of weeks before it becomes detectable.
Click to expand...
I bow to his knowledge and I agree that you won't have problems for a few weeks but I have not had problems up to several months. I the only reason I can't state I've had problems after this is that I don't leave it over several months.

I still conclude: If inexperienced use secondary but plenty of experienced brewers leave it in primary for more than a couple of weeks with good results.
 
Also, while autolysis does happen (I think we have come to that conclusion), it is unlikely that it will contribute to off flavors in beer. It is also less likely to contribute off flavors if you pitch healthy yeast at appropriate amounts (starter or rehydrating).
 
I have also found that a 3 week-month primary to be helpful to my brews as opposed to hurtful. I do admit that there could be subtle flavors there from autolysis but I just don't know what to look for.

I suppose a way to test this is to do a 10 gallon batch and secondary one of them, give it a good month on the yeast/secondary and see what if any differences there are. I don't think I have a refined enough palate to do this.
 
conpewter said:
I suppose a way to test this is to do a 10 gallon batch and secondary one of them, give it a good month on the yeast/secondary and see what if any differences there are. I don't think I have a refined enough palate to do this.
Click to expand...
this is a great idea for a beer swap.
 
My wife and I went to a wine class last night and the subject was sparkling wines. This included tasting 6 different sparkling wines. We got a thorough lecture on sparkling wines production, including the influence of autolysis while undergoing secondary fermentation to produce the CO2 for carbonation. In this case autolysis is a good thing - were not talking a lot of yeast here, just what collects in the neck of the bottle while carbonating. It definitely affected the flavor. A number of the sparkling wines had a definite yeasty/bready aroma which we were led to believe was due to autolysis of some yeast.

It may be that this is much easier to detect in sparkling and still wines. I taste/drink a fair bit of wine too and have decided that I can get a pretty good feeling for the flavors/characters of a wine with just a tiny sip. I can't do that with beer. A tiny sip is not enough. I find I have to have a decent mouthfull to fully appreciate a beer. I'm thinking it may be the fullness of beer (higher FG vs wine) that makes it more difficult to pick out subtleties in flavor compared to wine. It could be the higher alcohol too
 
I thought the following comment from Wyeast was interesting....

An increase in pH indicates autolysis is occurring.
Click to expand...

Has anyone spent the time to see what the pH does over an extended period of time?
 
MNBugeater said:
I may have a completely unscientific comparison I can provide. I brewed 10 gallons of an Irish Red nearly 4 months ago. I fermented in 2 separate fermentors. 5 gallons was kegged about 30 days +/- after pitching and gravity readings had stabilized. The other 5 gallons just happens to still be sitting in the fermentor. At the time I kegged the 5 gallons, I only had 1 available keg. I had planned on bottling the other 5 gallons, but the holiday season hit, parties, family visiting, etc. and quite honestly I just didnt get to it. I knew it was there, but I didn't feel like I needed to panic. I did move it to a 45 degree room after about 6 weeks and it has been sitting in there ever since.

I now have an open keg and will keg it this week.

I made a note to report back here in 2 weeks when I do a side by side comparison. Not that there aren't multiple variables at play here, but I definitely have a brew that has been sitting on yeast for 4+ months and if there are any distinguishable flavors from autolysis, I should taste them.
Click to expand...

Follow up on this unscientific and unplanned experiment...

I finally kegged this Irish red approximately 5 months after sitting in the primary. No racking to secondary, no dumping of yeast/trub. This was straight from boil kettle to pitch yeast and here we are 5 months later.

While my palette isn't experienced or trained in detected the off flavors produced by autolysis, I did set up a side by side taste test. I emptied the last of my 1st keg of Irish Red into a 2 liter growler with a beer gun (we dont need no stinking beer gun, actually) and put it back in the keezer. I then filled the keg with my Irish Red that had been sitting in the primary for 5 months. I waiting about a week for it to carb and then I had 3 buddies over for our weekly beer night gathering and we sampled side by side the recently kegged Irish Red (5 months in primary) and original kegged Irish Red (4+ weeks in primary).

No one could tell a difference. In fact it wasn't 3-4 minutes into the experiment that we forgot what glass was which. They tasted so similar that we could not tell. We kept drinking the kegged Irish Red the rest of the night and everyone thought it was a great beer. We even tried to detect and notice the off flavors that autolysis is supposed to produce. We could not detect the proverbial "sulpher, meaty, or rubber" flavors associated with autolysis.

OH....YMMV :drunk:

EDIT: I sent 2 bottles of this into Nationals, so I will be sure to report any commentary relevant to 'off flavors due to autolysis'. But if it is a ****ty beer for any other reasons don't expect to hear about them :)
 
Long two weeks ;)

Although not a great test, I had the last beer from my 3rd batch (bottle conditioned) last night and didn't detect bready/yeasty or anything else overpowering. It wasn't great but it is a 1.5 year old Irish Red extract brew.
 
I just racked a stout to 'secondary' after about six months and I didn't notice any off flavours. The OG was 72 and the SG at time of racking was 24. For the style it seems off flavours would be nearly undetectable. eh as far as the debate goes, I'll rack my beers whenever.
 
Autolysis = more esters. Esters are fruity, yielding a more fruity beer. Some esters, a metabolic "by-product" of protein and carbohydrate metabolism in yeast, do not cross the cell barrier and are thus retained within the cell. That is, until it dies thereby releasing these esters.

JBB : Vol. 96 (2003) , No. 2 p.110-118
 
I just got a pumpkin beer into the secondary today and mine had a dried burnt rubber flavor and aroma....I did what any brewer would do.... add more spice and let it sit...lol.

My buddies from the same batch, different yeast turned out very decent with no off flavors or bad aroma. I used a White Labs Ca ale (WLP051) and he used S-04.

Is it possible my rubber tastes are from autolysis?? brewed on 9-7-09, so it hasnt been on a yeast cake for an excessive time. Anyone have any input?? Dont want this to happen again???
 
My 2 cents.
If the off flavors produced by autolysis are fruity esters, than I am a believer. I made the exact same beer 2 months apart, same Pale ale recipe, fermentation, type of yeast, everything. My first one sat in primary for 6 weeks. My second 7 days. Completely different tasting beers. 1st batch was much too fruity for the recipe I had done a dozen times. I didn't care for it much. 2nd batch tasted perfect, actually the best beer I've ever made, Blue ribbon at the competition I entered.
The only difference I could figure was probable autolysis of the 1st batch.
 
Just a data point: On Jan.1 of this year, my neighbor came over to get a feel for brewing. He left with a five gallon bucket of IPA that we brewed, pitched with an unrehydrated packet of S-05.

One thing led to another, and it didn't get bottled until mid-September. I didn't detect any sulfur or meaty flavors or aromas in the bit we sampled. So, a total of nine months in the fermenter. The beer had been stored at 65F in his basement all summer.

My two cents worth is that for us homebrewers, working on the usual time scales, with healthy yeast, it's unlikely to be a problem.
 
Orfy said:
Thanks for the emails.

I bow to his knowledge and I agree that you won't have problems for a few weeks but I have not had problems up to several months. I the only reason I can't state I've had problems after this is that I don't leave it over several months.

I still conclude: If inexperienced use secondary but plenty of experienced brewers leave it in primary for more than a couple of weeks with good results.
Click to expand...
Orfy,
Not only the inexperienced use secondary (for many reasons besides autolysis) but also experienced. In my case over 30 years. It is quite obvious that you are biased toward primary only. That's fine and good for you. But, the evidence is quite plain, autolysis is a real event! It begins within two weeks. Many of us just don't mind the transfer to secondary. To each his/her own. After all it's a hobby.:)
 
jds said:
Just a data point: On Jan.1 of this year, my neighbor came over to get a feel for brewing. He left with a five gallon bucket of IPA that we brewed, pitched with an unrehydrated packet of S-05.

One thing led to another, and it didn't get bottled until mid-September. I didn't detect any sulfur or meaty flavors or aromas in the bit we sampled. So, a total of nine months in the fermenter. The beer had been stored at 65F in his basement all summer.

My two cents worth is that for us homebrewers, working on the usual time scales, with healthy yeast, it's unlikely to be a problem.
Click to expand...

The point I'm trying to get out there is that the autolysis that occurs as a normal part of growing yeast in culture DOES NOT produce the meaty, rubbery, nasty flavors. Those result from more then just simple autolysis, my guess would be an infection.

Autolysis = more esters. Esters are fruity, yielding a more fruity beer. Some esters, a metabolic "by-product" of protein and carbohydrate metabolism in yeast, do not cross the cell barrier and are thus retained within the cell. That is, until it dies thereby releasing these esters.

JBB : Vol. 96 (2003) , No. 2 p.110-118
Click to expand...

I typically associate autolysis as bready/yeasty flavors.

An interesting tidbit in the JBB paper is that all maltose wort produce less esters, and the addition of fructose and glucose promotes ester formation. Makes me wonder about the saying that adding sugar to Belgian beers is to dry them out. This makes me wonder if that is only part of it, and that a major benefit to adding sugar is increased ester production
 
I made a one gallon batch of leftover hefeweizen with extra wort that didn't fit in my kettle and it sat on the yeast for 3 months before I knocked out my keg and racked it over. It tastes like bananas completely after carbonating. Pretty sure its autolysis 100%. So far the most off flavored beer out of all my beers I've made, but it was essentially a leftover wort experiment. Debating on dumping it, but it may go okay with the bananas foster ice cream cake in my freezer. Autolysis can occur is the point.
 
rideincircles said:
I made a one gallon batch of leftover hefeweizen with extra wort that didn't fit in my kettle and it sat on the yeast for 3 months before I knocked out my keg and racked it over. It tastes like bananas completely after carbonating. Pretty sure its autolysis 100%. So far the most off flavored beer out of all my beers I've made, but it was essentially a leftover wort experiment. Debating on dumping it, but it may go okay with the bananas foster ice cream cake in my freezer. Autolysis can occur is the point.
Click to expand...

I'm pretty sure banana flavor is a characteristic of hefeweizen yeast strains and it is an ester usually dependent on how well the yeast is treated. I.e. Proper pitch rates, temp controlled fermentation, nutrients, o2 etc etc. And not due to autolysis. Just my opinion if I am wrong I'm sure someone more intelligent will say where.



Sent from somewhere to someone
 
rideincircles said:
I made a one gallon batch of leftover hefeweizen with extra wort that didn't fit in my kettle and it sat on the yeast for 3 months before I knocked out my keg and racked it over. It tastes like bananas completely after carbonating. Pretty sure its autolysis 100%. So far the most off flavored beer out of all my beers I've made, but it was essentially a leftover wort experiment. Debating on dumping it, but it may go okay with the bananas foster ice cream cake in my freezer. Autolysis can occur is the point.
Click to expand...

Autolyzed yeast is described as a burned rubber or rotten meat flavor. Banana is a characteristic ester of hefeweizen yeast and becomes more pronounced the higher fermentation temperature gets. Like GilSwillBasementBrews said, it's probably fermentation temp, pitch rate, nutrients, etc.
 
I have a beer that has been on the yeast for about 4 years. I brewed it, my gf left me and I was in a bad place in life for a long time. The carboys have just been sitting there for years, i wonder if that beer is any good anymore... Any opinions?
 
RedIrocZ-28 said:
I have a beer that has been on the yeast for about 4 years. I brewed it, my gf left me and I was in a bad place in life for a long time. The carboys have just been sitting there for years, i wonder if that beer is any good anymore... Any opinions?
Click to expand...

It depends on so many things- how much yeast is in the bottom, the yeast strain, the temperature, etc. A light dusting of yeast may not have much impact, but a huge amount of trub at 80 degrees may be absolutely fecal.

Open it, taste it, and see! If you can't bear to taste, at least smell it close up and see if it smells good. It might be ok, or at least not terrible. Or, it might be a dumper.

Only one way to tell!
 
RedIrocZ-28 said:
I have a beer that has been on the yeast for about 4 years. I brewed it, my gf left me and I was in a bad place in life for a long time. The carboys have just been sitting there for years, i wonder if that beer is any good anymore... Any opinions?
Click to expand...

I would dump it. A fresh start on life deserves a fresh brew.
 
I've experienced autolysis once. It was a beer that I let sit on the yeast for almost 9 months. I kept some bottles of it trying to see if the flavors would go away with time, they never did.

After 4 years, the bottles were finally dumped when we were moving


Sent from my iPhone using Home Brew
 
I did two 5 gal batches amber ale with a 1.5 liter starter of reharvested/washed wpl001. First batch all grain, second mini-mash. I split the yeast starter between the two batches.

Fermentation for both batches seemed normal. 10-13 day primary, Extract batch is delicious. All grain batch: yeast smells gross and meaty FG pretty low @ 1.010 from MOG of 1.050.

Autolysis ..wild yeast?. Is yeast autolysis absolutely a function of how long the beer sits on trub in primary or could it also occur during a normal 1-2 week primary as in my last brew.
 

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