What is actually happening to my beer while it lagers for 8 weeks?

I made a bock using Wyeast Hella-Bock yeast and I'm leaving it in my fridge near 32F for 6-8 weeks. What is happening to my beer that it has to sit for that long?

You know how we say that "the yeast like to go back and clean up after itself?" That's exactly what is happening during the lagering phase.

Here's what palmer has to say..It's kind of over simplified, if you want more info look for stuff written by Noonan, including his book on lager brewing.

Palmer said:

Lager yeast produce less fruity esters than ale yeasts but can produce more sulfur compounds during primary fermentation. Many first time lager brewers are astonished by the rotten egg smell coming from their fermentors, sometimes letting it convince them that the batch is infected and causing them to dump it. Don't do it! Fortunately, these compounds continue to vent during the conditioning (lagering) phase and the chemical precursors of other odious compounds are gradually eaten up by the yeast. A previously rank smelling beer that is properly lagered will be sulfur-free and delicious at bottling time. Speaking of Time...

...Lager comes from the German word "lagern" which means to store. A lager beer is in cold storage while it ages in the conditioning phase. Temperature influences lagers in two ways. During primary fermentation, the cooler temperature (45-55 °F) prevents the formation of fruity esters by the yeast. In addition to producing fewer byproducts during the primary phase, the yeast uses the long conditioning phase to finish off residual sugars and metabolize other compounds that may give rise to off-flavors and aromas.

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Basically lager yeasts, even more than ales produce a lot of sulphuric and other compounds during fermentation, and then slowly during the lagering phase, clean it up.

I would think the yeast wouldn't be doing anything at 34F. But hey, I'm new.

jetmac said:

I would think the yeast wouldn't be doing anything at 34F. But hey, I'm new.

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Ale yeast yeah...but that's one of the inherent differences between lager and ale yeast...their operating temp range. There's still a few swimming around taking out the garbage, after the party.

jetmac said:

I would think the yeast wouldn't be doing anything at 34F. But hey, I'm new.

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If you look at the specification sheet of a typical lager strain, <40F is not within the temperature range of the yeast, so your comment would make sense.

However, that temp range is what the manufacturer consider ideal for primary fermentation where the yeast is working in their full mode. The lager yeast is very versatile; it ferments way beyond its given range, even at Ale temps but also at very low temps.

It's all starting to make sense

Ok.. got me thinking and wondering.. I read somewhere that your lager temp should be 10 to 15 degF below your fermentation temp. A lot of folks 'round here seem to express the idea that the closer you get to freezing without freezing the better.

I'm bringing this up because it seems that maybe the 10 to 15 deg rule is really right and maybe going close to freezing just clears things better and faster but doesn't let the yeast clean as well? I'm planning my first lager later this year (been only doing ales so far) and am still trying to decide what temps I am going to use etc.

jetmac said:

I would think the yeast wouldn't be doing anything at 34F. But hey, I'm new.

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In the traditional practice they do. Most of the good lager homebrewers I know let the beer fully attenuate and mature at the primary temperature or an elevated temperature. If you do that, the beer is clean going into lagering and then the lagering phase is just to remove protein-polyphenol complexes and yeast. If you did not do a decoction (which creates excess tannins) this won't take all that long.

theonetrueruss said:

Ok.. got me thinking and wondering.. I read somewhere that your lager temp should be 10 to 15 degF below your fermentation temp. A lot of folks 'round here seem to express the idea that the closer you get to freezing without freezing the better.

I'm bringing this up because it seems that maybe the 10 to 15 deg rule is really right and maybe going close to freezing just clears things better and faster but doesn't let the yeast clean as well? I'm planning my first lager later this year (been only doing ales so far) and am still trying to decide what temps I am going to use etc.

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Not sure where you read that but German lager breweries lager at -1 to -2 Celcius, so they aren't following that rule.

remilard said:

In the traditional practice they do. Most of the good lager homebrewers I know let the beer fully attenuate and mature at the primary temperature or an elevated temperature. If you do that, the beer is clean going into lagering and then the lagering phase is just to remove protein-polyphenol complexes and yeast. If you did not do a decoction (which creates excess tannins) this won't take all that long.

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I've asked this question point blank before since reading Chris White's book where he says the yeast just aren't going to do much/anything below 40F. Why chill the yeast and make them work slower? Never made a lot of sense to me. I've read that the colder the better in precipitating out the protien-polyphenol complexes you mention.

Hermit said:

I've read that the colder the better in precipitating out the protien-polyphenol complexes you mention.

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Bingo, we have a winner!!!! Clearing is a big function of lagering. Most of the undesirable flavors should be "removed" before lagering is begun.

Hermit said:

I've asked this question point blank before since reading Chris White's book where he says the yeast just aren't going to do much/anything below 40F. Why chill the yeast and make them work slower? Never made a lot of sense to me. I've read that the colder the better in precipitating out the protien-polyphenol complexes you mention.

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Yes the temperature is a bigger factor than the time. 1 week at 28 F is better than 4 weeks at 40 F. Times are much shorter for homebrewing than for commercial (talking about precipitation here) because our tanks are much shorter.

Some lagers, notably doppelbock, may benefit from extended storage at warmer temperatures if you want them to have dark fruit "aged" character.

So to be clear then, lagering is not about having the yeast do anything, other than drop out? I've heard about the sulfur dissipating, but where would it go in a sealed keg? I lager in my serving kegs, and they get a lot better after a month or two.

StMarcos said:

So to be clear then, lagering is not about having the yeast do anything, other than drop out? .

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.....and if that holds true, what the heck takes lagers longer to do this than ales?

theonetrueruss said:

Ok.. got me thinking and wondering.. I read somewhere that your lager temp should be 10 to 15 degF below your fermentation temp. A lot of folks 'round here seem to express the idea that the closer you get to freezing without freezing the better.

I'm bringing this up because it seems that maybe the 10 to 15 deg rule is really right and maybe going close to freezing just clears things better and faster but doesn't let the yeast clean as well? I'm planning my first lager later this year (been only doing ales so far) and am still trying to decide what temps I am going to use etc.

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Like I fermented at 51F, so 15F below that is 36F, which is about where it's at now.

So like under 40F is where you want to be?

jetmac said:

.....and if that holds true, what the heck takes lagers longer to do this than ales?

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Probably because they are doing the same thing just at colder temps... I am repeating myself here but I usually condition my lagers at room temps. I have tried the same batch and split the bottles - half at room temp, and half at lagering temps... they tasted exactly the same. Not saying I proved anything, but I will not even bother lagering given the yeast seem to clean up just fine at higher temps.

I'm a believer that the lagering has less to do with yeast activity and more to do with small chemical reactions, flavors melding, slight bits of positive oxidation, clarification, and other things that are very difficult to quantify and yet you can really taste a difference as a beer continues to lager.

I put a bock on tap after a couple weeks fermentation and about 6 weeks of lagering. I knew it wasn't totally ready when I put it on tap, but I was impatient and thirsty. Lo and behold, a few weeks later I was amazed at how much better it continued to get. It's almost inexplicable - you hate to say things like, "it had more flavor" but that's really what it was like. Complexity.

I would be interested to do an experiment comparing a batch split into two lagering conditions. One near freezing and one at 60-70deg. Any guesses on how they might taste relative to one another? I would think one would want to get the beer off the bulk of the yeast before the batch was split.

I brewed my first lager last September; a Bohemian Pilsner. I had always thought the lagering process was for storage and for conditioning the beer, not for the yeast to do anything. Based on that, I filtered my Pilsner with a 1um setup and then put the keg in the chest freezer to lager for a couple months. The 1 um filter is supposed to remove a high percentage of the yeast. I do this to reduce my purine intake (gout sucks!). Even with pretty much no yeast left in the pilsner, it certainly got better after a couple months of lagering at ~34F. It got even better after two more months of lagering. The last pint I poured was the best one of the keg. That was quite possibly my best beer yet.

Based on my very limited experience with a single lager yeast strain, the yeast didn't need to be there during the lagering phase.

That being said, I am doing two lagers now and I will not filter either of those until after they have completed the lagering phase. Not sure if it will make a difference, but I'd prefer to do it the traditional way to build my confidence that the final beer will be good in the end.

kanzimonson said:

I'm a believer that the lagering has less to do with yeast activity and more to do with small chemical reactions, flavors melding, slight bits of positive oxidation, clarification, and other things that are very difficult to quantify and yet you can really taste a difference as a beer continues to lager.

I put a bock on tap after a couple weeks fermentation and about 6 weeks of lagering. I knew it wasn't totally ready when I put it on tap, but I was impatient and thirsty. Lo and behold, a few weeks later I was amazed at how much better it continued to get. It's almost inexplicable - you hate to say things like, "it had more flavor" but that's really what it was like. Complexity.

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Every time I tell someone this "Nontraditional" Bock will be done in 10 weeks(8 weeks @ 34F in secondary and 2 more weeks carbonating in the keg) they say "What?" "10 weeks" "that's crazy". Then I get on HBT.com and you guys always back me up. I just know this beer will be the shiznut if I have the patience to wait. :rockin:

StMarcos said:

I would be interested to do an experiment comparing a batch split into two lagering conditions. One near freezing and one at 60-70deg. Any guesses on how they might taste relative to one another? I would think one would want to get the beer off the bulk of the yeast before the batch was split.

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Why guess? I have done it - twice. I noticed no difference between the two, maybe your experience will be different than mine though. Try it!