Beer Forum

Heres my issue:

I have 10 gallons of helles that I brewed and chilled to 47, pitched a big starter ala pitching rate calculator, and rose to 50 to ferment for 2 weeks. i did the diacetyl rest for 3 days. heeding the advice of a few pro brewers on the session, specifically the Dan, I transferred to a couple of cornies, and sealed them off....purging twice a day and dropping the temp to 45 F. I played that game for 2 more weeks and then crashed and transferred to another keg to lager. two weeks in, there is still quite a bit of diacetyl. What sucks is that without that butter....it is quite a mouth watering helles.

Here are my questions:

Can I pitch a starter at high krausen and leave for a couple days and lager for a couple weeks on the new yeast?

For future endeavors, should I just leave the helles on the yeast for 4 weeks before thinking of transfer? I have always been paranoid about autolysis.

Thanks for the help.

Can I pitch a starter at high krausen and leave for a couple days and lager for a couple weeks on the new yeast?

Yes on adding the starter @ high krauesen, but bring the beer up to D-rest temps (60F or so) first, then add the active yeast and leave at that temp for a week or so. Then TASTE the beer to see if a longer D-rest is needed. If not, cold crash and lager as usual. I'd also do the starter at 60F so it can keep going in the beer once it's added without any temperature shock.

Keep us posted.

After a 3 day diacetyl rest you shouldn't have diacetyl I would be looking for the source of the problem. Formation of diacetyl requires conditions including valine poor wort, oxidative state, a yeast strain that is prone to produce it, insufficient contact between beer and yeast during lagering, warm (in lager terms - 50°F is getting up there) fermentation temperatures or spoilage bacteria. As you can't very well accuse your LHBS guy of selling you valine poor malt and demand that he give you your money back you'll have to focus on the other aspects. If it is really strong after the diacetyl rest I would consider infection. Is it really that strong or is there the possibility that you are unusually sensitive to it as some people are? Another thing is that people have been taught to believe that diacetyl is a bad thing. Period. It isn't in moderation. I remember a conversation with a professional brewer (I didn't know who he was at the time) in which he said "There is no place for diacetyl in lager beer." My response was "Really, do they know that in Pilsen?" Granted, at high enough levels (sarcina sickness) it can be pretty nasty stuff but at levels at and near threshold it helps produce that nutty carmamel flavor we assiciate with Pils and the Czech pilsners contain measurable (and tasteable) levels of it. I'm not a Helles brewer so I can't commnent as to what level is tolerable in that style.

Getting the beer into a reduced state will convert diacetyl to acetoin and subsequently 2,3 butanediol which has a much higher flavor threshold and the usual way to do this is reintroduce active yeast as you propose to do. If that works then great. Problem solved. It is important that the yeast be kept in suspension for as long as it takes to reduce the diacetyl. Too rapid settling of the yeast during lagering may be the cause of the problem in the first place.

If kraeusen beer doesn't solve the problem it may be because there is so much diacetyl that the yeast can't handle it and in that case I would suspect the aptly named Pediococcus damnosus. But it usually presents with other nasty symptoms like slime ropes and acidity.

A desperation measure (it's a bandaid at best) which you mich want to try on a sample of the beer to see if it works is the brewers second best reducing agent, sodium or potassium metabisulfite (the best is active yeast) available the the LHBS as Campden tablets. Metabite will reduce the diacetyl to 2,3 butanediol but this has a flavor too and not, IMO, a pleasant one so that if there is enough diacetyl you may still wind up with a beer you don't like. This works with water solutions of diacetyl in the lab (well, out on the deck - I've learned not to open that bottle in the house) and should, thus, work in beer. There is also the chance that the unused metabite (and the sodium or potassium from the used metabite) may render the delicate Helles less that what you had in mind. So let's hope the kraeusen beer does the job.

Another possible solution is "tincture of time". Part of what is supposed to happen during lagering is the redution of diacetyl by the yeast. This is why it is important to have as large a yeast/beer interface as possible (why some brewers put their lagering cornies on the side and the idea behind "Beechwood Ageing" chips). I wouldn't be too hopeful because if three days at diacetyl rest temperatures didn't get it I doubt that a couple of months at near freezing will.

ajdelange wrote:Is it really that strong or is there the possibility that you are unusually sensitive to it as some people are? Another thing is that people have been taught to believe that diacetyl is a bad thing. Period. It isn't in moderation. I remember a conversation with a professional brewer (I didn't know who he was at the time) in which he said "There is no place for diacetyl in lager beer." My response was "Really, do they know that in Pilsen?" Granted, at high enough levels (sarcina sickness) it can be pretty nasty stuff but at levels at and near threshold it helps produce that nutty carmamel flavor we assiciate with Pils and the Czech pilsners contain measurable (and tasteable) levels of it.

IMO, diacetyl is something that can always be avoided with good brewing practices. So why not structure your brewing to avoid it entirely? While I've not been to the Pilsen region, I've had many fresh Czech pilsners while traveling Europe. I found plenty that were free of diacetyl, which I have a very low threshold for. As far as German lagers go, everything I've come to know disallows diacetyl at any perceptible levels for all styles.

Also, it was my understanding that the richer malt character associated with Czech pils, as opposed to German pils was due to elevated melanoidin levels.

SacoDeToro wrote:
IMO, diacetyl is something that can always be avoided with good brewing practices.

Agreed or I might say "managed" rather than avoided since it is part of some styles. When I said in the previous post that a diacetyl rest shouldn't be necessary I was thinking in terms of an appropriately selected yeast strain managed properly from which you should obtain the proper level of diacetyl for the style (or substyle - thinking of Czech vs German Pils here).

SacoDeToro wrote: I've had many fresh Czech pilsners while traveling Europe. I found plenty that were free of diacetyl, which I have a very low threshold for.

I won't say there aren't exemplars of low diacetly Boh. pils out there as I've only measured 2 - Budvar and PU and they are pretty highly regarded (to the point where there have been many attempts to reproduce them). I can't find my notes for Budvar but PU comes in at 0.21 mg/L and as I recall the Budvar was around 0.17 - not overwhelming by any means in either case but for that synergysm with the malt it shouldn't be. According to Narziß the threshold is 0.10 - 0.11 mg/L (and he speaks of detrimental effect on flavor at levels above this) and the measured levels for these 2 Czech beers is about twice this. Diacetly isn't a primary flavor for sure - nor would we want it to be.

I do not do a diacetly rest but rather lager for extended periods. My Boh. Pils measures around 0.1 mg/L (low enough to make Ludwig N. happy) which probably contributes a bit to caramel/nutty notes but not to the extent it does in PU and my beers done with the "PU" strain don't have that quality . Rumor has it (and I can't glorify it as any more than a rumor) that PU is a blend of worts fermented with as many as 5 yeasts and that one of them is cultivated for it's diacetyl production. When I tried to scrounge yeast sample(s) from PU I didn't get any. I got the runaround ("Is lab closed today".) To be fair about it, the lab might have been closed that day.

OTOH the pils I do with the Budvar strain resembles Budvar more closely in flavor than the PU strain product resembles PU and while I haven't measured the diacetyl on a brew with this (the Budvar) strain I'm resolved to do so. I note that I am tasting one of these as I write this. It is now 9 months old and thus very well lagered (on the yeast). That nutty quality is now less prominent than when the beer was younger (it tastes less like Budvar) and I have to wonder if the yeast haven't been scavenging diacetyl bit by bit over the lagering period.

SacoDeToro wrote:As far as German lagers go, everything I've come to know disallows diacetyl at any perceptible levels for all styles.

Well we know how Narziß feels about it anyway. Kai?

SacoDeToro wrote:Also, it was my understanding that the richer malt character associated with Czech pils, as opposed to German pils was due to elevated melanoidin levels.

I think that's part of it but not the whole story. When I was there (PU) over 10 yrs ago they were, as far as I could tell, still doing triple decoctions (PU is darker than most German Pils) but apparently diacetyl is acceptable in perhaps the 2 best known examples of Czech brewing at twice the level (and twice the perception threshold) that it typical for German beers. Again Kai may have further information on this.

Diacetyl is interesting stuff (the legal aspects of its use in flavoring aside). At very low levels it give a rather pleasant caramell/nut flavor (or at least does this in synergism with Maillard products). At slightly higer levels it is perceived as buttery which transitions to butyric and then beyond butyric nasty as concentration increases.

BTW I found in my notes that in commercial preparation of acetoin diacetyl is reduced through the catalytic action of zinc ion at low pH. I tried this out on my deck this afternoon and found that once again it seems to work though acetoin tastes fairly buttery as well (used in margarine's etc.). The test was done with RO water (which is at a pH in the 5's) so it ought to work at the pH of lager beer. I used zinc sulfate (which I do not recommend) but perhaps a zinc strip or penny or 2 in the lagering vessel might help reduce it.

But I firmly agree that proper management of yeast much of which I believe to be related to keeping it in suspension during at least the first phase of lagering (see Kunze) is much better than trying to apply bandaids after the fact.