Autolysis - Does It Really Happen?

[2duck]

Hi all

I recently bottled a beer - AG Alt, Wyeast 1338 - after nearly 2 months in the primary. There was not a trace of autolysis, which I understand as yeasty/vegemity/burnt rubber aroma (and presumably taste). A friend also recently bottled a beer after over 2 months in the primary with no problems. It got me wondering about how much of a problem autolysis really is for the home brewer. I have been reading on this site for about a year now (although this is my first post), and I've read lots of mentions of the risks of autolysis, but I don't remember ever reading a post from someone who suffered it.

Obviously yeast does die. I have kept yeast harvested from previous brews under water in the fridge, and if I keep it more than a few months then when I open the jar a burnt rubber smell hits me straight away. I also once opened a Wyeast packet to be greeted by that burnt rubber smell. To satisfy my curiosity I pitched that yeast to a starter. It was dead alright.

What I really wonder is whether there is much of a risk of yeast death in a fermenter under home brew conditions in time scales of a couple of months or so.

It might matter because I am inclined to think that the beer really improves with more time in the fermenter, and we may be inhibited from giving it more time because of fears of autolysis.

Has anyone had a brew turn to vegemite in the fermenter?

 

[Barry]

Poor yeast to begin with or too long at a high temp will possbly cause it. Only worry if it is a worry, then be concerned but don't worry.

 

[schooey]

Yes indeedy doodly, Ned! I put down two beers together and got called away with work for weeks and couldn't get back to rack/keg them. One was a chocolate porter pitched with dried S-04, the other was a NS Summer Ale with the wyeast 1099 Whitbread. The choc porter was in primary for about 7 weeks, the NS Ale for about 6. The porter took a sample of to my LHBS where there were a few in the know bystanders who all had a taste. I asked them all what was wrong with it without offering anything up and they all said "Autolysis" back in unison. I kegged the 20L of it and carbed it, burped it, flattened it repeat for about 10 cycles and it became very drinkable.

The NS Ale however has not respondd at all and still tastes foulish. I'm almost ready to dump 50L of it... :blink: So I don't know whether different yeast strains are more prone to autolysis or what, but I definitely know it does happen.

 

[goatherder]

Not me.

If the yeast is in good health to begin with and your temps are reasonably controlled then autolysis is a pretty low risk. I've kept beers on primary for 5 weeks and not had a problem.

I'm a huge advocate of leaving a beer on primary until it's finished - about 2 weeks for an ale and 3 for a lager. I don't know how much better it will get when left longer than this. It doesn't seem to get worse in a hurry.

Fear of autolysis seems to be one of the reasons why people feel the need to use secondary fermenters. I don't think it's a valid reason - get your yeast right to start with and treat it nicely during fermentation. You don't need a secondary.

 

[Leigh]

I had one British Ale that sat on the yeast for 6 weeks, during a heat wave when I was o/s (so no hope of getting it off the yeast)...I bottled it anyway...tasted like off vegemite, had a few "experts" tell me it was yeast autolysis and to dump it as you "can't ever get rid of the taste"...well lazy me didn't bother dumping it, but I did open a bottle every month or so, noticing that each bottle was slightly better than the previous. After 5 months of conditioning it was a really nice drop. After 9 months it was great!

This one was sitting on the yeast at 25 degrees when I arrived home, and the best of the heat wave had passed (over 35 degrees inside the house!)...

I don't think the heat did the beer any favours, but I for one don't believe it was yeast autolysis that occured...

I have used a secondary on occasion, but only to get a clearer beer

Most of my beers sit on the trub/yeast cake for at least 2-3 weeks, some as long as 5 weeks!

 

[newguy]

I never transfer to secondary. The longest I let the beer sit on the yeast cake is 3 weeks for ales and 4 or 5 weeks for lagers, if really cool. I don't get autolysis from these contact times, but my fermentation temperatures rarely exceed 22 or 23C. If things were warmer, I'd be more concerned.

That said, autolysis does happen. I don't know about it being reverseable, though. I've been a beer judge for 10 years, and you do come across the odd beer with autolysis. It's definitely not common, but it exists. In very low levels or very early on, autolysis (to me) smells just like flintstones vitamins. The first few times I smelled flintstones vitamins in a beer at a competition, I had no idea what the cause was. And you can't write "flintstones vitamins" in the aroma section either. Then one day I opened an empty keg that I had left sitting at room temperature for several months. It was sealed but had a wee bit of beer and some yeast in the bottom. As soon as I opened it, there was that flintstones vitamin smell, but there was also a low soapy/fatty aroma too. And then it hit me - I finally knew that flintstones vitamins = start of autolysis.

 

[wyatt_girth]

I filled my first keg yesterday with a fresh wort pack, NNL Sparkling Blonde, that had been sitting on the yeast cake for only two weeks. I have had a heater belt running at 18 deg off a fridgemate. I was suprised to pick up a hint of a vegemitey smell when I opened the fermenting fridge. This was my first experience with this smell so I was thinking that maybe my brew belt had contributed to autolysis. It isn't any lower down on the fermenter than I would normally have it.
I went ahead and kegged it anyway, it was to be my first after all so was gonna give it the benefit of the doubt. fter draining the fermener I opened it up and stuck my melon over the top and took a whiff - no vegemite.
Will wait and see how it turns out. This keg was supposed to supply a handful of people at my daughter's 3rd birthday next week so I hope it is ok (apart from being green).
This was using safale S-04 if it makes any difference.
I think this was going to be a question when I started so....... any comments?

Cheers,
wyatt

 

[Weizguy]

It's true. Autolysis happens, but usually due to abuse or lack of care.
Mostly due to heat or cold stress. See here
Same for fusels. And if you're really bad (or slack), they will both occur simultaneously.
Does anyone like acetone in their Vegemite?

 

[Muggus]

I find it has happened to me in high gravity stouts which i've left for several weeks in the primary. But having said that, we're talking about an uncontrolled temperature environment, during warm weather, on a yeast cake that is probably no where near as healthy as it should be.
So i'm thinking the vegemite (autolysis?) flavours in those stouts down to over stressing the yeast...but I could be wrong!?

 

[braufrau]

That said, autolysis does happen. I don't know about it being reverseable, though. I've been a beer judge for 10 years, and you do come across the odd beer with autolysis. It's definitely not common, but it exists. In very low levels or very early on, autolysis (to me) smells just like flintstones vitamins. The first few times I smelled flintstones vitamins in a beer at a competition, I had no idea what the cause was. And you can't write "flintstones vitamins" in the aroma section either.

I had to look up what flintstone vitamins are! I'm guessing you don't know what vegemite smells like either.
When we lived in canada, we could get it in the stock section of the local safeways.

 

[braufrau]

And what's that revolting smell that used to (still does??) come wafting overr the river from CUB?? That's autolysis isn't it?

 

[dr K]

Autolysis happens, no doubt about it, but you do have to try a bit to get it happening.
Finished beer should ideally be kegged/bottled/conditioned without delay, but it needs be actually finished, too early and you may have to deal with diacetyl and acetaldehyde, at the very least!
Contamination aside an extra week on the yeast at fermentation temp or below is not going to hurt your beer drastically, longer than two weeks..its just got to be downhill. Oxygen is number one enemy, it is going to get to your beer and cause untold damage, as you have no active shields against contamination (your yeast is asleep and the CO2 is well gone) your chances of infection multiply, aerobic bacteria, particularly the type that love to bathe in enthanol are ready for a field day, and if that were not enough you may under certain circumsatnces get autolysis.
I guess I have judged more than a few times in my life and I have to say that in beers entered in competitions autolysis as the only flavour fault is extremely rare.
Of course if we were talking Chamapagne we may take a different tack.

K