Filtering/Lagering

[Buttwidget]

Looking for some process advice... In some of the Brew Strong Episodes I heard that filtering and lagering accomplish many of the same goals. I'm not feeling so sure and want to lager my brew, but filter it as well. Call it me being "doubly sure".

So, I have a lager that has fully fermented. I am about to rack it to secondary for a two month lager period tomorrow. The thing is, I wonder if I should filter it on the way in to the lagering vessel or should I hold off, rack it, let it lager and then filter it into the keg?

I understand the effects of filtering on the flavor of the beer, and I understand about using aseptic techniques to ensure things don't oxidize. Additionally, I am not worried about "more work" being involved, this is strictly about process and quality.

Essentially the question is: Filter then lager, Lager then filter, or Filter lager and filter.

Any (qualified) advice?

Buttwidget

[edisonst]

You want to lager with plenty of yeast still in suspension. So you would want to lager the beer and then filter. If you filter first the lagering wont do much. I did a split 10 g batch this year of munich lager. I filtered one keg after 2 months and let the other sit. There was very little difference between the two. I served both kegs after between 2.5 and 3.5 months of cold conditioning. If you have the time to do extensive lagering I think filtering is a waste. I even transported the unfiltered one to a wedding and did not knock sedement into suspension. I would only filter a lagered beer if the yeast refused to drop or there was a haze that needed to be removed. Kolsch yeast and altbier yeasts are ones that I would expect the possible need for filtration. I use wyeast munich lager yeast for my lagers and have never had the need to filter them.

[Elbone]

Lager for 8 weeks -> Try -> Realize your beer is awesome and crystal clear and you don't need to filter -> tie one on in celebration.

[ajdelange]

Not sure about the qualified part but here goes anyway.

In filtering one removes yeast and protein globules which brightens the beer. In lagering these, over time, settle to the bottomof the lagering tank and so the beer brightens from lagering as well. But there is a big difference in the outcomes. In lagering the beer is still exposed to the yeast and the whole purpose of lagering is to maintain that exposure. During lagering the yeast "clean up" the beer. Most important here is the uptake of diacetyl and acetaldehyde but other reactions take place as well. Filter out the yeast and all this comes to a screeching halt. So yes, you can lager and then filter (i.e. wait until the beer tastes right and then filter it if it isn't bright enough) but not the other way around. But the only reason to do this would be if you want brilliantly bright beer. I don't like beer that looks like the branch after a storm but as long as it is reasonably clear that's plenty good enough for me and I find that storing the beer over the yeast (and cold) it stays drinkable for a year or more.

[Buttwidget]

Interesting. Thanks for the feedback...

If I remember the lagering Brew Strong correctly, JZ and Palmer said that yeast doesn't do anything at lagering temperatures and that lagering won't change a beer that wasn't fermented properly (which is why I did a tightly controlled fermentation with a diacetyl rest at the end. I wanted to ensure that I had a great beer to begin the lagering process with.

Filtering is obviously for clarity, I'm looking for a very bright beer. Lagering is something that (I admit) I don't understand fully, but it seems that we are using the cold temps to drop solids out of suspension.

Maybe someone can explain what else is accomplished by lagering and how?

Thanks!

Buttwidget

[ajdelange]

If I remember the lagering Brew Strong correctly, JZ and Palmer said that yeast doesn't do anything at lagering temperatures...

I hope you don't because those guys should know better.

...and that lagering won't change a beer that wasn't fermented properly (which is why I did a tightly controlled fermentation

But is is true that lagering won't 'fix' a beer that is 'broken' because of a poor fermentation. It should be clear that the yeast, though in a state or repressed metabolism, need to be in good health to do the things that need to be done during lagering.

..with a diacetyl rest at the end. I wanted to ensure that I had a great beer to begin the lagering process with.

There are 2 approaches to lager fermentation. In the traditional one the yeast are piched below fermentation temperature and the temperature allowed to rise, held and then lowered again for lagering. A diacetyl rest is not required. The lagering gets it. In the other, fermentation is at higher temperature and allowed to go higher still for diacetyl clean up. This is a much faster process than the traditional (which nominally takes 3 months) and so much more popular today.

Filtering is obviously for clarity, I'm looking for a very bright beer. Lagering is something that (I admit) I don't understand fully, but it seems that we are using the cold temps to drop solids out of suspension.

Yes, that's part of it. Proteins become less soluble at low temperatures (chill haze) and these have the opportunity to coalesce and/or complex with polyphenos and precipitate out. Note that this should render lagered beer chill proof but it doesn't alwaus work that way. Lagering is also a time for calcium oxalate to precipitate lessening the likelihood of gushing and the formation of stones in the drinkers. The CO2 evolved by the yeast tend to "scrub" out jungbuket (beer stench) and, as live yeast keep everything in a reduced state, tend to turn potential oxidizers in to reductones. Very important in this regard is the reduction of VDK's to the very much less flavorfull homologous diols and acetaldehyde to ethanol. We also speak of melding and mellowing of flavors and that is certainly a large part of it. Well fermented, well lagered beer is very very smooth.

[Tygo]

I re-listened to part of the Brew Strong podcast and took a look through the Yeast book and my impression from those is the same as the first time I read/listened. And that is that lagering under 40F causes the yeast to become dormant and not contribute much to the process at all.

I didn't hear or read the statement, "Yeast does nothing at temperatures below 40F." but the above is what I took away those sources.

Obviously there's some disagreement on that point. Is there really enough yeast activity to make a difference if you're holding the beer at 33F? Or would lagering at somewhat higher temperatures, closer to and approaching 40F be more effective?

Perhaps it's a trade-off between very cold temperatures causing things to precipitate out and somewhat higher temperatures allowing the yeast to continue to work.

I don't know the answer. Just some thoughts.

[Buttwidget]

Thanks for the input AJ and Tygo. I wanted to move my beer into the lager freezer and study it to see what I could deduce and then bring that info back to the conversation (which is why I haven't checked in on the topic recently). Here's what I've found:

AJ is right, they said that lagering won't "fix" a beer, they didn't say it won't change a beer. Great example of how we filter and put things that we hear into a context that may be different than the original intent. Evidently words mean something...

For this beer, I chilled to just a few degrees above fermentation temp and pitched (ground water too warm to bring it down any further). Dropped it into a temp controlled fermentation environment with a 2 degree temp variance. Fermented for 2 weeks at 48, and then walked the temp up to 65. After 3 days at 65 all fermentation indicators ceased. I waited two more days, racked it off the yeast into a 5 gallon carboy with only 2 inches of headspace in the neck of the carboy between the bung and the beer, and then moved it to the lagering freezer. Its now been lagering for a week at 33 degrees. I've seen some suck back in the airlock (hasn't pulled sanitizer into the container) and absolutely no action to indicate that the yeast is metabolizing anything. With such a small amount of headspace, I would expect to see some movement in the airlock indicating positive pressure buildup if the yeast was doing anything.

To me, this says that the yeast is dormant during lagering (at this temp at least) and the clarifying action that is happening is that solids are precipitating out. I've heard in a few places since that lagering and filtering accomplish the same thing. I'm wondering if this is true, I don't have enough experience or data to determine what the difference in flavors might be. It seems that just like a tomato sauce, providing time for the flavors to blend will make for a better sauce, that time will allow the flavors in a beer to mellow and blend making a better beer. What I don't see (with my limited data points) is yeast having any contribution to this effect. Where I am at right now is that a good fermentation accounts for all the effects of yeast that you are attributing to lagering and fermenting, and the melding and mellowing are a result of the lagering process. Don't take that the wrong way, I'm just trying to characterize my observations against your knowledge and hopefully gain some deeper understanding.

Thoughts, comments?

Thanks for your insight.

Buttwidget