Autolysis - Why doesn't it happen in the bottle?

[NickW]

HI all,

Was pondering this today...

We aren't meant to leave our beer on the trub for any extended amount of time because there is a said risk that the yeast may start to eat itself...

But why doesn't this happen in the bottle? When we bottle condition there is 500ml of beer sitting on a thin layer of sediment... is it because we are keeping our beer cool after the initial warm priming phase? Is there not enough yeast in this layer for autolysis to be an issue?

 

[calumscott]

I guess it probably does happen, just not in sufficient volume to cause a problem.

Here is where we need Aleman's input. He's bound to have read loads on this in the past...

 

[adomant]

It will eventually, depending on the type of yeast. Some beers are bottled and primed with a different yeast, mainly because it clears and settles better but also because some yeast strains (e.g. Lager yeast) don't autolyse so much.

Sometimes opening a really old bottle you get that unsalted marmite aroma

 

[calumscott]

Sometimes opening a really old bottle

I never seem to have that problem... :hmm: :whistle: :lol:

 

[GavH]

So if the answer is "it does", the follow on question begs to be asked: "after how long?". Has anyone seen any data regarding time taken for different yeast strains autolysing in the bottle?

 

[evanvine]

Could this be something to do with the "sell by" date?

 

[RobWalker]

I'm sure that on a commercial level the weight of the liquid and trub has a lot to do with it. In the bottle there's little more than a whisker in there.

 

[oldbloke]

OK, I don't actually know, BUT that's never stopped me shooting my mouth off before...
The amount of dead yeast is very small, it almost certainly gets autolysed, but I reckon this adds to the characteristic flavour of the beer. This only works because it's in such small amounts, like the number of anchovies the lamb was roasted with yesterday. Some top-end champagnes depend on it! (according to Wiki)

 

[Vossy1]

I've had a good skim though Brewing (Lewis and Young) and Yeast (Zainasheff) and it would appear the subject is not covered from a bottle conditioning perspective*. What is mentioned is the importance of not having too much yeast in the bottle, a small dusting is all that should be visible. As per oldbloke I would offer an opinion that this small amount shouldn't impact too much on flavour or head/haze, and I would question how many of the yeast are actually dead versus just dormant, though naturally they will autolyse with time.
It would be good to hear from those who have access to more definitive material, an interesting and good question

Bottle conditioning is covered but not this subject.

 

[Aleman]

It does.

Is it noticeable? Depends on storage temperatures as to the speed to which it would happen, and obviously the amount of yeast in the bottle. Ideally you want a single layer of paint thickness of yeast on the bottom of the bottle, any flavour compound released from that volume of yeast are going to be pretty unnoticeable in a beer (In a very pale delicate white wine that has a high degree of carbonation, then it is noticeable as a 'bready' - rising bread?? aroma/taste. Beer being a much more robust beverage would mask the flavours unless it is extreme. Even after 10 years in the bottle at a variety of storage temperature my imperial stout didn't show any signs of autolysis . . .plenty of other signs of age, but no autolysis.

 

[Vossy1]

Thanks A :thumb: I also found this brief overview on't web.
I'm hypothesising from some of the comments that this may be one of the reasons I've noticed decreased head retention on big IPA's stored over time :hmm:

As the yeast further deteriorates in the absence of nutrients, it releases proteolytic enzymes which degrade beer-foam proteins and also increase protein and carbohydrate hazes.

 

[Aleman]

Thanks A :thumb: I also found this brief overview on't web.
I'm hypothesising from some of the comments that this may be one of the reasons I've noticed decreased head retention on big IPA's stored over time :hmm:

As the yeast further deteriorates in the absence of nutrients, it releases proteolytic enzymes which degrade beer-foam proteins and also increase protein and carbohydrate hazes.

That's a really good resource V . . . Moritz is one of those guys that really knows his stuff and can be trusted. Autolysis is also one of those things that affect beer stability over time. . . . Of course if you are drinking a batch in 6-8 weeks you'll never notice it (Which some would take to mean that it doesn't exist ), but it is only after coming across and old bottle that is considerably older that you notice things are not as good as they first appeared.