[tomsawyer]

I have been letting my lagers sit in primary for 3-4 weeks at 50F before pulling the fermentor out for a few days at 60+ for a diacetyl rest.  There is generally no activity from the airlock at this point and things are settled out pretty well.

I've become concerned that my letting things sit around in a Better Bottle or bucket for that long is contributing a certain amount of oxidation.  I'm also leery of making a beer with a lot of diacetyl, so I'm conflicted about how to proceed.  My own sense tells me that it might be better to start the diacetyl rest towards the end of active fermentation rather than one to two weeks later.  This will presumably let more active yeast clean up the diacetyl and speed up the process so I don't have beer sitting around with little CO2 to protect it (in primary).

Any advice?

[davidgzach]

If you are pitching enough yeast, you probably do not need a diacetyl rest at all.  That being said, if you want to anyway, it's best right at the end of fermentation as you said.  The yeast are plentiful, still active and the rise in temperature gets them out to clean everything up. 

I would definitely not let a lager sit in a bucket for that long.  In the Better Bottle you are fine. 

[tygo]

My own sense tells me that it might be better to start the diacetyl rest towards the end of active fermentation rather than one to two weeks later.  This will presumably let more active yeast clean up the diacetyl and speed up the process so I don't have beer sitting around with little CO2 to protect it (in primary).

I do a diacetyl rest as a matter of practice on lagers whether I think it needs it or not and this is what I do.  Once I'm anywhere from a few to several points above my final gravity I bump the temp up by 10 degrees for the rest.

[hopfenundmalz]

I have been pretty much doing the Narziss schedule.  Let it ferment out about 75%, then raise temp for last 25% of fermentation. Example:  1.048 Pils, target of 1.012 FG.  Going down 36 points, so 1/4 is 9 points from the end.  So start the D-rest at 1.021.

This gives the yeast enough activity to clean the Diacetyl and scrub out the Sulfur compounds.

Go by what the beer is indicating, not the calendar.

[James Lorden]

I agree with hopfenundmalz.  Our timing is a little different but I basically do the same thing - once the beer is at about 1.5 degrees plato from expected final gravity (about 6 gravity points) I raise the temp from around 50 to around 60 to finish up.  If done this way then holding at 50 for 4 weeks wouldn't be necessary - I think you'll finish up faster and clean up much faster but there is a monitoring step added compared to the four weeks of set it and forget it.  If you are leaving the beer at 50 for 4 weeks I don't think that a diacetyl rest should be necessary.

[redbeerman]

I have been pretty much doing the Narziss schedule.  Let it ferment out about 75%, then raise temp for last 25% of fermentation. Example:  1.048 Pils, target of 1.012 FG.  Going down 36 points, so 1/4 is 9 points from the end.  So start the D-rest at 1.021.

This gives the yeast enough activity to clean the Diacetyl and scrub out the Sulfur compounds.

Go by what the beer is indicating, not the calendar.

This is what I do, but don't worry if you are a few points off.  It still seems to work well.

[bluesman]

I use the same procedure. Start slowly ramping up the temp at about 70% AA to a resting temp of 60F for several days until you've reached terminal gravity then crash cool the fermenter down to 32+F. Then rack into the keg and lager near freezing for 4 weeks. Any residual diacetyl will age out during the lagering period.

[tomsawyer]

My friend actually had diacetyl get worse during lagering.  I understand there is a precursor that can convert over time, I suppose that was the problem.  Or maybe he just didn't notice the diacetyl as much in the green beer.

I'll ditch the buckets for my lagers, I was wondering about that anyway.

It seems I'm making really slow progress on getting good results with lagers, compared to ales.  I'm finally producing some good products but its been somewhat inconsistent so hopefully this will be the last piece of the puzzle.  I already got a temp controlled freezer and am putting custom water together from RO.  Part of the problem is that it takes quite a bit more time before you get your results. 

[davidgzach]

My friend actually had diacetyl get worse during lagering.  I understand there is a precursor that can convert over time, I suppose that was the problem.  Or maybe he just didn't notice the diacetyl as much in the green beer.

I'll ditch the buckets for my lagers, I was wondering about that anyway.

It seems I'm making really slow progress on getting good results with lagers, compared to ales.  I'm finally producing some good products but its been somewhat inconsistent so hopefully this will be the last piece of the puzzle.  I already got a temp controlled freezer and am putting custom water together from RO.  Part of the problem is that it takes quite a bit more time before you get your results. 

Per my first post, are you making starters and are they BIG?  I had the same issue until I found out that I was severely underpitching. 

[Kit B]

I've been brewing light lagers with smoe really good success, just timing the diacetyl rest right at the fall of the krausen.
Today, I am using the same timing on a Munich dunkel.
I really, really hope that works out as well as the light lagers have.
I'm a little intimidated.

[hopfenundmalz]

My friend actually had diacetyl get worse during lagering.  I understand there is a precursor that can convert over time, I suppose that was the problem.  Or maybe he just didn't notice the diacetyl as much in the green beer.

I'll ditch the buckets for my lagers, I was wondering about that anyway.

It seems I'm making really slow progress on getting good results with lagers, compared to ales.  I'm finally producing some good products but its been somewhat inconsistent so hopefully this will be the last piece of the puzzle.  I already got a temp controlled freezer and am putting custom water together from RO.  Part of the problem is that it takes quite a bit more time before you get your results. 

Lennie,

Sounds like you are on the right track.  As stated, pitch lots of healthy yeast and treat them right.

The diacetyl precursor can turn to diacetyl with oxidation (says so in Yeast somewhere)  A long lagering time in buckets will let some O2 in, which will make the diacetyl worse.  If you bottle the finished beer and introduce some O2 and the precursor is there, then you get a buttery beer for the Judges - this happened to me in 2010.

I lager in corny kegs.  Now bottle with a Blichmann Beer Gun.

[tomsawyer]

Per my first post, are you making starters and are they BIG?  I had the same issue until I found out that I was severely underpitching.  

Sorry, yes I either make an appropriate stir plate starter or use yeast cake.  Not sure if my friend made a starter, that could be the source of his diacetyl difficulties.

I've been brewing light lagers with smoe really good success, just timing the diacetyl rest right at the fall of the krausen.
Today, I am using the same timing on a Munich dunkel.
I really, really hope that works out as well as the light lagers have.
I'm a little intimidated.

I brewed an Ofest that I was dissappointed with, and I am thinking it was oxidized.

[1vertical]

Seems to me that you could add a little bit of food back for the yeast and
when that is consumed, a quantity of CO2 would be produced blanketing
your beer...if oxygen was a major concern.  
Edit: this was Denny's advice to me once when I was concerned about O2