Lager Yeast

[therook]

I've done a fair bit of searching on this topic and have a couple of questions

I'm currently brewing a lager with Wyeast 2007 and pitched a healthy starter at 10c into a 1.048 wort, it has consistantly dropped 4 points a day and is down to 1.016 after 8 days, i'm NOT going to give it a D Rest as after searching i'm led to believe if you Pitch cold then a rest is not warranted.

Questions

1. Is there a list of what yeasts produce more Diacetyl than others and to what levels ? I have looked at the Wyeast site and it tells me some yeasts do produce it, do i assume if it doesn't mention it then it wont be produced.

2. and to carry on from that, what temp does Diacetyl start to be produced

Clear as mud

Rook

 

[SJW]

Good questions. Sorry I can't answer them.

 

[SJW]

Only joking. I would say check out the Wyeast web site.
I am a big fan of 2000 Budvar at the moment. I ferment all my Lagers at the lower limit and do a rest at 15 deg C regardless.
Just remember to pitch a good size starter slurry and you will be able to forget about attenuation issues.

Steve

 

[floppinab]

Both good questions and I can't answer them either but I am finding on my lager ferments that a temp rise over the back end of the ferment does seem to produce a more effective result in terms of final gravity, cleaner finish to the taste of the beer. As a rule I'm pretty much stepping up to something like 18 deg from say 11 deg over the last 3 or 4 days prior to crash chilling/racking for a secondasry. I'm pitching cold like you, diacetly or no diacetyl I'm finding it just produces a better result.

This is pretty much what the big boys do but of course they use a much more aggressive temp gradient and time frame.

EDIT : ^^^^^ Ah yes what the Novocastrian said!!!

 

[Katherine]

Where are you GB.....?

 

[brettprevans]

cant answer your question there rooky. i D-rest all my lagers. of course the pain at the moment is getting your beer to D-rest temp in melb at the moment given that you can lager outside without any assistance (my brews is sitting no higher than 10C out in the open - obviosuly its not getting any sunlight so it doesnt skunk)

 

[jonocarroll]

My understanding is that diacetyl is a byproduct that the yeast creates, given certain conditions. Yeast are pretty good at cleaning up after themselves, also given certain conditions. In this case, my understanding is that if you warm the fermented beer back up, the yeast will clean up any diacetyl.

I'm not entirely sure that pitching cold eliminates the ability to produce diacetyl, and unless there's a particular reason to skip it, I'd be giving the brew a D-rest. Is it too much of a problem?

It's not a proper answer to your questions, but it's the best I've got;

I thought all yeasts were able to create diacetyl, and it was just a matter of which were more prone to producing too much, i.e. lager yeasts. From How-To-Brew (YMMV)

Diacetyl is most often described as a butter or butterscotch flavor. Smell an unpopped bag of butter flavor microwave popcorn for a good example. It is desired to a degree in many ales, but in some styles (mainly lagers) and circumstances it is unwanted and may even take on rancid overtones. Diacetyl can be the result of the normal fermentation process or the result of a bacterial infection. Diacetyl is produced early in the fermentation cycle by the yeast and is gradually reassimilated towards the end of the fermentation. A brew that experiences a long lag time due to weak yeast or insufficient aeration will produce a lot of diacetyl before the main fermentation begins. In this case there is often more diacetyl than the yeast can consume at the end of fermentation and it can dominate the flavor of the beer.

(my emphasis). So ale yeasts can produce it too. This would also imply that it's not just a temperature-based thing. i.e. there's no 'diacetyl will be produced above/below this temp.'

Hope that helps.

 

[Adamt]

Have a taste. If you can taste diacetyl you need to raise the temp.

 

[A3k]

From my memory of a different section in how to brew, diacetyl is also a byproduct of yeast growth.
If you have a small amount of yeast to start, then the yeast will need to multiply causing diacetyl. Generally when you pitch a small lager, youll pitch warmer to help the yeast multiply.
The diacetyl rest is used to overcome this problem and allow a smaller starter.

I could however be wrong, and dont have the book infront of me, but the lager section of how to brew is where I got it from.

EDIT: I was trying to say, pitching a large enough starter, allows you to pitch cold and should result in lower levels of diacetyl.

I think the book also mentioned a D Rest only needing to be 3-4deg above ferment temp.

 

[jbumpstead]

My understanding is that diacetyl is a byproduct that the yeast creates, given certain conditions. Yeast are pretty good at cleaning up after themselves, also given certain conditions. In this case, my understanding is that if you warm the fermented beer back up, the yeast will clean up any diacetyl.

I'm not entirely sure that pitching cold eliminates the ability to produce diacetyl, and unless there's a particular reason to skip it, I'd be giving the brew a D-rest. Is it too much of a problem?

It's not a proper answer to your questions, but it's the best I've got;

I thought all yeasts were able to create diacetyl, and it was just a matter of which were more prone to producing too much, i.e. lager yeasts. From How-To-Brew (YMMV)


(my emphasis). So ale yeasts can produce it too. This would also imply that it's not just a temperature-based thing. i.e. there's no 'diacetyl will be produced above/below this temp.'

Hope that helps.

+1

The yeast will cleanup the diacetyl at the warmer temp so when brewing an ale diacetyl will still be produced but will be cleaned up by the yeast without any changes in temp as the wort is already at an appropriate temperature.

I personally wouldn't risk it- do a D-rest. Warm it up for a couple of days. The majority of your primary fermentation will be complete so it won't do any harm in terms of taste. Put it in the house, or on a heat pad.

Bumma.

 

[jbumpstead]

Anyone interested in the how and why of diacetyl:

http://beerme.com/diacetyl.php

No affiliation.

Bumma.

 

[jonocarroll]

http://beerme.com/diacetyl.php

Gotta love the little bit of blatant editorialising at the very end...

Contrary to what the BJCP Style Guidelines might imply, beers without diacetyl taste a lot better than beers with diacetyl. Try this experiment: walk down the popcorn aisle at your local grocery store and take a deep breath. Do you want your beer to taste like that? I didn't think so.

 

[jbumpstead]

Gotta love the little bit of blatant editorialising at the very end...



Contrary to what the BJCP Style Guidelines might imply, beers without diacetyl taste a lot better than beers with diacetyl. Try this experiment: walk down the popcorn aisle at your local grocery store and take a deep breath. Do you want your beer to taste like that? I didn't think so.

Ahh but if the popcorn aisle smelt like a nice hoppy beer it'd be a different story.

Edit: formatting

 

[Stuster]

If you want some technical information on diacetyl, Trough Lolly has posted some detailed info in the past on it. Here's a small snippet from this thread.

Not at all Ross, you're quite right!
//warning - serious beergeek mode on!//

There are, however two problems that make the elimination of diacetyl quite challenging. The first problem is the presence of the precursor to diacetyl and the second problem is the characteristics of the yeast strain itself.
The generation of diacetyl in beer is not actually dependent on the yeast. The diacetyl precursor - alpha acetolactate - undergoes a spontaneous oxidative decarboxylation and converts into diacetyl (2,3-butanedione). Two major influences in this process are pH and temperature (there are, of course, other factors including oxygen levels and oxidative ions such as iron or copper that also convert the precursor to diacetyl).
Taking a step backwards, we need to understand how the alpha acetolactate got there in the first place and the prime culprit is the yeast itself - generating the alpha acetolactate as a result of synthesising valine and leucine amino acids from the wort during the "active" or attenuative phase. The fact is that if we could use a yeast strain that didn't generate any alpha acetolactate, or we got hard core and added alpha acetolactate decarboxylase that converts the alpha acetolactate to acetoin and bypasses the diacetyl stage, we wouldn't have any diacetyl. The yeast strains that we use do unfortunately secrete alpha acetolactate, but that rate of secretion does vary between strains.

So, the problem we have is active yeast that yes, is quite capable of scrubbing out the diacetyl present in the fermenting wort, but at the same time, is quite possibly still secreting the diacetyl precursor. And this is why I'm not all that convinced that giving the beer a diacetyl rest when the attenuative phase is not complete, is the best solution. Yes, it works, but it's possible that the diacetyl rest is better done in the window of opportunity between the end of primary fermentation and when the yeast is flocced out and dormant, ie there is still yeast in suspension, before lagering, that still have diacetyl reductases present to scrub the diacetyl out of the fermented wort...

This is demonstrated by brewers who experience "late bloom" diacetyl in their beer. They can't detect any diacetyl when fermentation has completed and they do a short diacetyl rest then rack to lagering or simply skip the rest and rack the diacetyl free beer straight to lagering, only to find to their dismay the presence of diacetyl some weeks later when they sample from the lagering vessel....Why is this so?! tongue.gif ph34r.gif
A common answer is oxygen - unless you rack under CO2, you can inadvertantly add oxygen during racking into the lagering vessel and that oxygen converts the alpha acetolactate present in the pre-lagered beer, into diacetyl. And of course, since you lagered the beer, the yeast is inactive so it won't clean the diacetyl up...

Let me apologise for rabbiting on, but I'm not convinced that a diacetyl rest should be rushed into - I see your logic but it gets easily contradicted by the active yeast taking on the role of prime culprit in the precursor generation stakes. Perhaps the generation of the alpha acetolactate drops off substantially as we near the end of the attenuative phase - I don't have clear data on that, but I'm gonna stick to my standard procedure and do the diacetyl rest at the end of the primary fermentation and not beforehand.
//beergeek mode ends//

Whatever - hey, let's have a beer!! cool.gif
Cheers,
TL

 

[Pumpy]

most lager yeasts are very similar I like Whitelabs 833 bock as it gives a nice malty taste

Pumpy