Autolysis - Does anybody really know?

I can't seem to find any good information about this. Or I should say I've found a lot of conflicting information.

On a homebrewing scale, is autolysis a concern for beer left in the primary fermenter?

If so, how long, and how do variables like gravity, yeast strain, and temperature affect?

What does autolysis taste like? Has anybody ever had to dump a batch because of it?

It seems that this is one of the most mis-understood areas of homebrewing. I understand that we will not likely get any really concise answers, but any experience helps. I've also noticed this is an area where the Wiki can really use some work, too.

I think over-hyped is a better word than mis-understood. I don't believe anyone on the board has seen autolysis in a fermenter, which is why there isn't much in the wiki.

I've seen it twice. Once in a cake that sat on my back porch for 4 months in the summer and the second one was a four-year old vial of -005 that got lost in the fridge.

One word: cesspool
Not septic tank, not sewage, cesspool.

So would you say than that beer sat on a cake for 4 months may be at risk for autolysis?
You'd also mentioned it was summer time. Do you believe the heat had some influence?

I THINK that I have had a batch that stressed the yeast to their limits. The timeline was:

Harvest 2 pints of slurry from blonde ale that was originally a single pack of US-05.
Pitch slurry into 10 gallons of 1.055 beer, ferment for 9 days.
Pitch 10 more gallons of 1.055 beer on that yeast cake.

While that last batch fermented out just fine in about a week, I swear this stuff smelled aweful. I've smelled this in a jar of slurry I had saved for a really long time. It made me want to puke.

The cool thing was, given 3 weeks aging in secondary, the smell started to subside as the yeast compacted at the bottom. Once I racked it to keg and carbed it, it was a wonderful beer.

Moral? It's more about yeast health than time.

I think I experienced autolysis when I tried to save lager yeast in the primary for to long. I racked my first lager off of the yeast cake and left 1/2 an inch of beer over the yeast cake and let it sit for 3 weeks. At which point I dumped 1/2 the yeast into a new carboy and put fresh wort on top of both. The beer definitely had some "off" flavors that I attributed to the yeast, but it could have been any number of other things besides Autolysis, so I am a little heasitent to say that is exactly what it is.

I did a poll on this a while back, and almost nobody had experienced it. The only place it seemed to crop up was in fermenters that were going for many, many weeks.

https://www.homebrewtalk.com/showthread.php?t=30219

What confused me is when people like Dave Miller say, "Because most homebrewers lack refrigeration capability, autolyzed, yeasty flavors are one of the most common defects of homebrew." (Miller 178)

Citation:
Miller, Dave. Dave Miller's Homebrewing Guide: Everything you need to know to make great-tasting beer. North Adams, MA: Storey Publishing, 1995.

I've asked about autolysis before and have received the same responses. Nobody has problems with autolysis. Maybe in the past 10-15 years yeast strains have been designed to prevent this problem.

Firstly, yeast strains are no more "designed" than are viruses or bacteria.

Secondly, few people have experienced autolysis here because it is rare and there is probably little gray area. It's either okay, or it smells like a big vat of rotten eggs. If your beer doesn't smell like rotten eggs, then it's probably not autolysising (not a word!)

Third, Dave Miller seems to be confooozed. "Yeasty" flavors are a far cry from "autolysis" flavors. One tastes like, well, yeast, while the other tastes like, well, ROTTEN EGGS. Just ask Palmer. He claims to have experienced it firsthand.

Beer or wine left at celler temps takes months and months before autolysis becomes a concern. I've talked to 4 brewmasters and they all said the same thing.

If you let your carboys sit in summer heat, then things start to break down faster. But then, why the hell would you do that to your beer anyway?

When I was in College I left a carboy (Primary) in my parents cool basement for over a year before bottling it. No problems at all.

BlendieOfIndie said:

What confused me is when people like Dave Miller say, "Because most homebrewers lack refrigeration capability, autolyzed, yeasty flavors are one of the most common defects of homebrew." (Miller 178)

Citation:
Miller, Dave. Dave Miller's Homebrewing Guide: Everything you need to know to make great-tasting beer. North Adams, MA: Storey Publishing, 1995.

I've asked about autolysis before and have received the same responses. Nobody has problems with autolysis. Maybe in the past 10-15 years yeast strains have been designed to prevent this problem.

Click to expand...

I am thinking he may be confused. Yeast bite is not unusual in unfiltered, green beer, but it'll subside with age, especially after putting the brews in the fridge for a week. I am extremely sensitive to yeast in my GI tract, which is why I make damn sure to wait until most of the yeast settles out. If I can taste it, I don't drink it.

Autolysis on the contrary, is something that would show limited or no improvement with time and taste quite different.

A beer in which autolysis has set in will have a very prominent and distinctive taste of burnt rubber and is completely undrinkable. There is no definitive time period in which it will set in as it depends on the health of the yeast which is another reason to make correct sized yeast starters. It's a game of chance as to how long you can get away with leaving the beer on the yeast cake but if your yeast is healthy, 2-3 weeks in the primary is fine, you can get away with leaving it much longer however the longer you leave it the greater the risk of autolysis is.

Evan! said:

Firstly, yeast strains are no more "designed" than are viruses or bacteria.

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Psst ... I've designed any number of viruses in my day, and some bacterial strains, to boot. Hell, I've even designed some mice, which are making up the majority of my thesis!

Brewed a special bitter before (read: not a strong beer OG-wise - maybe 1.045) and it got left in the primary for, oh... at least 6-7 weeks. Turned out to be one of the better beers I brewed.

However, this was in a basement, fermenting at low 60s, so who knows... I normally do a 3 week primary or so and make better beer since when I switched over from 1-2-3 method of my newb days.

I do usually always use a new packet of yeast each time I brew (I never reuse dry yeast)... I use dry more than liquid, so I've never even reused a liquid yeast more than twice. That will change in the future as I plan to brew a series of belgians, all with the same Abbey Ale yeast...

Evan! said:

Firstly, yeast strains are no more "designed" than are viruses or bacteria.

Click to expand...

Well you're prolly right in the sense that there's not a bio engineer sitting @ an autocad screen rearranging genes

But where do these new yeast strains come from? Are they not merely mutations of other yeast strains? If so, then I'd take it that many mutations are not very helpful. Therefore a yeast producer would need to weed out the bad mutations & only select the good ones. If this is indeed the process that occurs, then I would definitely call this "designing." If I'm incorrect (this IS just speculation) then I'd be interested in how new strains do come about

It was also a topic that confused me when I came to this forum.

All my books were very clear in that you should leave your beer in your primary FOR AT LEAST 10 days to make sure you remove any DMS or Diacetyl. But never longer then 30 days because thats when autolysis can start.

In reality, they were probobly just being extremely conservative. I suspect autolysis is one of those things that depends on a 100 different factors. Like OG, strain, temp, aeration, pitching amount, time, etc.

nick