What conditions cause autolysis - yeast death and rupture?

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Dynachrome

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From another thread....

Just wondering if you've ever tasted autolysis flavors in your beer?

Hmm, I thought I had, but maybe it was something else.

I have read about it in the older brewing books but most folks seem to consider it a boogie man now. I have left brews in the primary on the yeast cake for months and never noticed any I'll effects, but would be really interested in first hand accounts of those rubbery meaty off flavors! Don't want to hijack the OP's post, but I don't want to scare him with something he doesn't have to worry about either.

I should try an experiment. If it is an actual occurrence, it should be able to be duplicated, right?

I have a friend who is well read on beer in general, he mentioned it to me. He described it and I thought I tasted something in a beer we tested.

I'd like to challenge him. What are guaranteed conditions for autolysis?

Below, he didn't place anything under a microscope, or do any other testing:

John Palmer

Enzymes in the body:

Post mortem decay

OK, What does my batch have to do to insure autolysis?

No other living organisms, just the fun juices inside the yeast cells decaying.
 
Glad you didn't take offense to my post and thrilled with the experimental approach! Slainte!

Autolysis was a real and disgusting problem for brewers back in the day when they were peeling dry yeast packets of unknown heritage off of old cans of malt extract of equally suspect provenance. It was standard practice to rack to a secondary ASAP after active fermentation had finished. We, however, have access to ingredients arguably as fresh or fresher than the big boys. As I said in the other thread, I leave beers on the cake for at least 3-4 weeks and quite often longer. I leave cider for months. And I do this without hesitation because of feedback from many folks with way more experience here at HBT.

I think conditions for the experiments would be A) a fairly simple beer brewed with healthy yeast left for a very long time in the primary. You could pull samples at month increments and taste. It would help to have someone who knew what autolysis off flavors would taste like. Condition B) could be the same beer (split batch?) brewed with stressed, unhealthy yeast. Maybe really old dry yeast or a repitch from a huge hoppy beer. Pull samples at the same time. You could always throw in more variables such as aeration or wort strength. What do you think?
 
Not sure of a good way to do it, but I've heard an increase in pressure is one reason big brewers see autolysis and homebrewers do not. There is so much in a tank that there is an appreciable amount of pressure on the yeast at the bottom. I just don't know a good way to increase pressure (can't just use CO2 because it would not only increase variables, but it would go into solution).

We need an isostatic press!
 
Not sure if it's exactly the same with ale yeasts, but if autolysis in brewing is anything like autolysis in champaigne making, this experiment could take a while. Total yeast autolysis is essential to making a champaigne and the process can take from 5 to 10 years to complete.
 
Well, as I'm siting here this morning reflecting a little. My homebrew ends up with a little yeast cake in the bottom of the bottle. This doesn't seem to make any difference at all. Does this have something to do with proportion/critical mass? I personally left a carboy for more than 6 weeks in primary.

The other thread I was actually trying to help, but yeah - was I conjuring a Boogey-man that only comes out in murky nights where it is industrial brew with deep tanks, someone capping their fermentor too tight, someone setting their carboy too close to the boiler in the basement furnace area... etc.

TANSTAAFB Funny thing that you mention the funky old "yeast packets of unknown heritage off of old cans of malt extract of equally suspect provenance". That is what we were tasting. A guy had tried to revive an old kit. He brought it in for opinions. It wasn't that bad, just very mildly meaty. I think he had really limited means. We told him to put in a little carbing sugar and bottle it.

freisste In engineering, we refer to that as "head pressure" I believe.

More_Hops_Please I'm thinking it can be done with extra warmth too, from the small amount I've read so far. I don't want to tie up my on-and-only carboy for a long time. How about a liter bottle with a really disproportionately large amount of yeast?

I don't have deep pockets to do a whole 5 gallon batch of something - that if my experiment works - I'm going to flush down the wash sink with a bleach chaser either.

Could I do a small batch and have it get where I'm heading? I have 12 gallons of my bitter fermenting right now. I could cull a liter and not miss it. From what I can tell though, my beer stays extremely well in bottles.
 
Not sure if it's exactly the same with ale yeasts, but if autolysis in brewing is anything like autolysis in champaigne making, this experiment could take a while. Total yeast autolysis is essential to making a champaigne and the process can take from 5 to 10 years to complete.

Really? That is interesting. Is that part of the whole flavor/aroma experience.

It sounds contrary.
 
This is one of those things that could def take a while. It is a true concern of commercial brewers,since they have the weight of 100's of barrels of beer sitting on top of all that trub & settled yeast. That's another reason they try to ferment them out quickly. The bright tank or secondary is concequently very usefull in getting the beer off the yeast for them. It'd be tough to duplicate on our scale of brewing.
I'm not sure old yeast will work either. Maybe under the "wrong" conditions,if you will. I've used 2 year old yeast...even 3 year old yeast accidentally. But I rehydrated them & they worked just fine. So maybe try pitching old yeast dry would do it. Rehydrating them in the wort would make for weaker cell walls vs strengthening them by rehydrating.
 
Who would have thought, heavy breathing and stainless steel....



I was thinking of ways to make a hydraulic press. Something with a seal and a weight on one end of a hose - leading to sealed bottle. A five gallon bucket with a rubber bladder and a CMU block set on a plywood circle smashing down the bladder.

This would then place added pressure on the bottle contents.
 
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So maybe try pitching old yeast dry would do it. Rehydrating them in the wort would make for weaker cell walls vs strengthening them by rehydrating.

I was wondering if there was an under-pitch factor going on maybe. The yeast were stressed from starting with not enough survivors in the packet. ?

Re-hydrating with a little fermentable would give a higher pitch rate too, right?
 
Really? That is interesting. Is that part of the whole flavor/aroma experience.

It sounds contrary.

Yeah, autolysis creates much of the unique flavor of a well aged champaigne(as opposed to a "sparkling wine" where autolysis is absent). Given that champaigne yeast is different than ale yeast, I'm not sure how similar the molecular chemicals involved would be to autolysis in a brew. There are a lot of things you look for in wine making(tanin for instance) that you don't want anywhere near your beer.

I just figured looking at the autolysis process in champaigne might give you an idea of what time scale you'll be working with.
 
I'm no expert on the subject, but my understanding is that autolysis is exacerbated by temperature. That is, a warm temperature would encourage the breaking down of the cells. Pressure, too, so it might be hard to do it at home without ruining a big batch of beer.

One way to experience the "meaty" smell and taste of autolysis is simply to rack out your beer, and keep an inch or two of beer on the yeast cake and put it someplace warm for two or three weeks. That should do it.

Some winemakers do age sur lie- but it those cases, the lees are regularly stirred. That gives the wine a certain je ne sais quoi, but not a bad flavor. If the lees weren't stirred, though, that would create more of a bad off flavor. At least that is my understanding from winemaking.
 
I was wondering if there was an under-pitch factor going on maybe. The yeast were stressed from starting with not enough survivors in the packet. ?

Re-hydrating with a little fermentable would give a higher pitch rate too, right?

Dry yeast contains more cells than liquid yeast packages. They seem to account for losses when pitching dry. But not from the packet. It's from losses during rehydrating in the wort,which increases lag time as well.
Rehydrating in wort is the same as pitching dry. That's why rehydrating in water works a bit better,in conjunction with getting the yeast down to within 10 degrees of wort temp slowly before pitching. This makes for less attrition of yeast cells at pitch time,shortening lag time as a result.
So to try to simulate autolysis,pitch it dry in cooled wort in the fermenter. Old yeast would help it as well.
 
It's started.

I used a growler with an air-lock. I filled it over half full of trub and added some table sugar and some tap water.

The air-lock started going almost immediately. I sterilized everything. I used Vodka for the air-lock.

echS3R1menT.jpg


Trub.jpg


Beer.jpg
 
Dry yeast contains more cells than liquid yeast packages. They seem to account for losses when pitching dry. But not from the packet. It's from losses during rehydrating in the wort,which increases lag time as well.
Rehydrating in wort is the same as pitching dry. That's why rehydrating in water works a bit better,in conjunction with getting the yeast down to within 10 degrees of wort temp slowly before pitching. This makes for less attrition of yeast cells at pitch time,shortening lag time as a result.
So to try to simulate autolysis,pitch it dry in cooled wort in the fermentor. Old yeast would help it as well.

I didn't do a bunch of these suggestions because I had everything ready and could just go.

Also, I'm kinda good with my methods as stands for now.

This is because I was told if I let a regular batch of beer set in a carboy for too long, I will achieve autolysis.

I can always try to distress some yeast again later.
 
I'm no expert on the subject, but my understanding is that autolysis is exacerbated by temperature. That is, a warm temperature would encourage the breaking down of the cells. Pressure, too, so it might be hard to do it at home without ruining a big batch of beer.

One way to experience the "meaty" smell and taste of autolysis is simply to rack out your beer, and keep an inch or two of beer on the yeast cake and put it someplace warm for two or three weeks. That should do it.

Some winemakers do age sur lie- but it those cases, the lees are regularly stirred. That gives the wine a certain je ne sais quoi, but not a bad flavor. If the lees weren't stirred, though, that would create more of a bad off flavor. At least that is my understanding from winemaking.

For good measure, what, eight weeks unmolested, and see what happens?
 
When you bottle your next beer, pour the cake into a container, loosely seal the top (or the container will explode) and set it off to the side somewhere.

Then you will know what autolysis is.

I store my slurry in mason jars in the fridge, with the intention of using it within a couple of months. At 6 months at fridge temperatures there is an obvious autolysis smell starting to appear. At room temperature it should occur much faster.

You will know when you have it.

I think that once you start to starve it of the nutrients in the beer, it becomes cannibalistic.
 
Fascinating subject. Could you bottle a bunch of bombers with lots of yeast, then taste one per month, after say, 4 months?

Keep us up to date with your results.
 
When you bottle your next beer, pour the cake into a container, loosely seal the top (or the container will explode) and set it off to the side somewhere.

Then you will know what autolysis is.

That's what I did here. I revived the yeast with a little sugar to generate CO2.

I store my slurry in mason jars in the fridge, with the intention of using it within a couple of months. At 6 months at fridge temperatures there is an obvious autolysis smell starting to appear. At room temperature it should occur much faster.

You will know when you have it.

I think that once you start to starve it of the nutrients in the beer, it becomes cannibalistic.

From what I've read, when they actually die, their internal enzymes start to reduce them from within.
 
Fascinating subject. Could you bottle a bunch of bombers with lots of yeast, then taste one per month, after say, 4 months?

Keep us up to date with your results.

That's not a bad idea. I liked the other comment that it will even occur in a fridge. I have six growlers at my disposal, heck I've got plenty of bombers too.

Multiple containers of the same batch of trub. Tasted over a span of months.

Actually towards the end, I'm thinking maybe just a quick whiff, not a taste.
 
Not sure of a good way to do it, but I've heard an increase in pressure is one reason big brewers see autolysis and homebrewers do not. There is so much in a tank that there is an appreciable amount of pressure on the yeast at the bottom. I just don't know a good way to increase pressure (can't just use CO2 because it would not only increase variables, but it would go into solution).

We need an isostatic press!

Nope, you just need a spunding valve and a keg to ferment in.

https://www.homebrewtalk.com/wiki/index.php/Spunding

I do some pressurized fermentation, and once had some autolysis when my spunding valve got gummed up and stuck, resulting in very high pressure in the fermenter. As mentioned, pressure, heat, time, and yeast health are all contributing factors to autolysis, but pressure and heat are by far the biggest IME.

People leave beer in primary for months on end without autolysis. It could take a long while to acheive.

Yep, I've left beer on the yeast cake for 6 months without any hint of autolysis. I've left ciders for even longer.
 
JuanMoore said:
Nope, you just need a spunding valve and a keg to ferment in.

https://www.homebrewtalk.com/wiki/index.php/Spunding

Right. I know there are ways to pressurize beer. I was trying to figure out a way to pressurize without allowing extra gas to be absorbed into the liquid (like the conditions at the bottom of a very large fermenter where the pressure comes from the depth of the liquid, not the pressurized headspace).

But that is interesting information.
 
If you want to create autolysis, you don't want to feed it.

Thanks Calder.

I was just trying to expiate the oxygen and leave a CO2 blanket to keep aerobic bacteria off.

I did this to emulate a carboy, first fermentation, followed by a long setting period.
 
from my experience you can get autolysis by letting a beer go through primary fermentation and letting it clear in the same vessel, and then holding it at 80*F or better for a few more weeks in the fermentor. Works like a charm!
Plenty of dead and dormant yeast and nothing else around for them to eat, let the temperature get way up there to get them good and active, and taste the rainbow :drunk:
 
Never experienced it just from time in ales myself, even leaving brews on the yeast for two or three months.

But I always regret trying to brew in August, that's what I get for not setting up a cooler!
 
Hmm. I wonder. What if the autolysis is occurring in the "good" batches left on the yeast too? The difference could be that the chemical bouquet produced by autolysis at lower temperatures and/or pressures just isn't unpleasant.

Solid information on autolysis as it relates to brewing, has turned out to be surprising difficult to find. I will be following this thread with interest.
 
Right. I know there are ways to pressurize beer. I was trying to figure out a way to pressurize without allowing extra gas to be absorbed into the liquid (like the conditions at the bottom of a very large fermenter where the pressure comes from the depth of the liquid, not the pressurized headspace).

But that is interesting information.

The pressure at the bottom of a cylindrical tank will be the same regardless of diameter, so...
If you want to simulate a tall fermenter without requiring a huge volume of liquid for your test, then make it out of 3/4" SCH 40 PVC pipe. :mug:
 
MagicSmoker said:
The pressure at the bottom of a cylindrical tank will be the same regardless of diameter, so...
If you want to simulate a tall fermenter without requiring a huge volume of liquid for your test, then make it out of 3/4" SCH 40 PVC pipe. :mug:

I actually imagined that, but assumed it was impractical. If it is practical, I think it is a good way to simulate the big boys. As you say, diameter is irrelevant to pressure.
 
Hmm. The long tube is a good idea.

I hate to bring this up, but yeast cannibalization is a different process then autolysis. Inducing it through denial of nutrients, or excessive yeast stress, isn't going to produce any useful data. Autolysis occurs as a result of the enzymes present in the yeast cell after death. I rather doubt the chemicals, and therefore flavors, are the same.
 
Hmm. The long tube is a good idea.

I hate to bring this up, buy yeast cannibalization is a different process then autolysis. Inducing it through denial of nutrients, or excessive yeast stress, isn't going to produce any useful data. Autolysis occurs as a result of the enzymes present in the yeast cell after death. I rather doubt the chemicals, and therefore flavors, are the same.

I read this earlier, it didn't filter through though.

Are you saying that my growler experiment is too small?
 
My thought was the following:

People always say autolysis is a homebrew myth that the big boys deal with because their fermenters are so large. The size leads to higher pressure. This is a simple way to simulate the pressure the big boys get.

If you don't use a long tube (or similar) you can likely still achieve a condition which causes autolysis. Similarly, if you DO use it, you may NOT achieve the situation. It was just a thought that I thought might help.
 
I read this earlier, it didn't filter through though.

Are you saying that my growler experiment is too small?
Not exactly. Your growler experiment is a reasonable first experiment. I just don't think it will be definitive by it's self. There are still a fair number of factors that haven't been accounted for with that experiment.

Mostly, I was trying to point out that beating up on live yeast wasn't a useful thing to do when you are trying to study autolysis. It isn't any trick at all to induce yeast cannibalization, which we already know produces off aromas and negatively effects flavor.

My thought was the following:

People always say autolysis is a homebrew myth that the big boys deal with because their fermenters are so large. The size leads to higher pressure. This is a simple way to simulate the pressure the big boys get.

If you don't use a long tube (or similar) you can likely still achieve a condition which causes autolysis. Similarly, if you DO use it, you may NOT achieve the situation. It was just a thought that I thought might help.
Pressure is one of the factors that the growler experiment does not account for. However, I'm not sure it's necessary to account for it. If you are running the experiment for primary scientific reasons, then yes. A long tube or some other method to simulate the pressure of a larger fermentor would be useful. If you are only interested in autolysis as it effects, or doesn't, homebrew then it isn't necessary. Homebrewers don't typically have fermentors that are deep enough to produce the pressure you are talking about.

Another factor that had occured to me is the chemical composition of the brew it's self. PH, mineral and/or salt content. I seem to remember salt being used to encourage autolysis in soy sauce production. I'll see if I can dig up the reference. Temperature also springs to mind. After all, why is it that so many sources recommend aging at cellar temps?

EDIT: This wasn't the original reference, but it works I think.
http://en.wikipedia.org/wiki/Yeast_extract
 
Yeah, I'm trying to roughly duplicate regular home brew conditions.

The tall tube fermentor is probably fairly well off track.

No basement heaters.
No sunlight warming it up.
Small, but not un-imaginal size fermentor.

My thesis: What happens when you let your beer sit on a yeast cake for "an extended" period of time.
 
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