lager fermentation and Lagering question

Yes, this beer gets better when lagering at 40 F for a month, it is the way it reahes its flavor peak.

 

You might consider leaving it in the primary for 2-3 more weeks. I have had lagers that I thought tasted ok after one week show diacetyl in the second week. Give the yeast longer to do their thing.

 

Not only would I give it more time in the secondary, I would base my lager time on the coldest temp practical. If in the low 30s it might finish in a month. Because I lager in my keezer (40°) I tend to go 7-8 weeks. In all cases I would error on too long rather than too short.

Here's some pretty good ideas from BYO . . . more info here.

 

The question wasn't directed at me, but the answer is zero. See the second link in my post above.

 

I think that byo article is perpetuating a myth that there us something magical about bulk aging. I have lagered in bottles and not found fault with the process. However, you want to make sure your beer is ready to bottle , and that means not taking it off the yeast too soon .

 

I personally find with lagers that having the yeast clear is essential to get an authentic lager taste. Otherwise the taste is generally not as clean as is might be. Patience is well worth it as far a lagers go.

 

Agreed, one man's opinion, zero data or references. From the article: "But the fact is that beer doesn’t generally age well in the bottle"... uh huh. The last third of that article is a bunch of voodoo nonsense about things he thinks but has no evidence for.

 

Clearing the beer is the main object of lagering and is why big industrial brewers have mostly replaced lagering with intense filtration plants involving multiple steps. Before beer filtration, lagering was the only was to get a clear beer unless you were willing to add fish guts or seaweed, two things that Bavarians don't approve of. For hopper styles like pilsner, you do get some smoothing and rounding of hop bitterness and flavor as well, but I think a lot of this is again due to particulate matter dropping out of the beer.

Sulfur reduction is another goal of lagering, as some yeast strains produce a large amount of sulfur compounds at the end of primary fermentation. This will slowly reduce over the lagering period. Carbonation was historically another main goal of lagering and is still traditionally done with beers being transferred to a pressurize able lagering tank with a small amount of fermentable extract left to condition the beer in a sealed system. On the home-brew scale, this can be done be transferring to keg just before terminal gravity. The key to the early transfer method though is a very slow reduction in temperature that preserves yeast metabolism. If you crash the beer down to freezing in a day or two, you are going to shock the yeast and most of it will go dormant. At work we come down from a diacetyl rest temperature of 13C to 0C over a five day period to let the yeast slowly acclimate to the lower temperature. That being said though, we are not actually looking for the yeast to carbonate the beer at this point and don't start cooling until we are at terminal and pass a diacetyl test. Coming down before this period is done has a lot to do with why Czech lagers traditionally have diacetyl as part of their flavor profile as this is still a typical method there, while German brewers have mostly adopted the diacetyl rest fermentation curve before lagering.

 

Kai Troester does a very good job discussing making lager beers here: http://braukaiser.com/wiki/index.php?title=Fermenting_Lagers

The ‘executive summary’ from that link:

“A lager fermentation consists of these 3 phases:

• primary fermentation : main fermentation of the fermentable extract. The bulk of the CO2 and alkohol are created here
• maturation : the yeast is allowed to clean up some of its byproducts like diacetyl (butterscotch flavor) and acetaldehyde (green apple flavor)
• cold stabilization (lagering) : the low temperature causes haze forming proteins and polyphenols come out of solution and drop out of suspension. There is also a mellowing of flavors and some formation of esters happening. The latter becomes only significant after more than 12 weeks [Narziss 2005]”

My take-away for the lagering phase:

· It gets larger proteins and polyphenols to drop out

· The yeast continues to condition the beer (albeit at a slow rate due to colder temperatures)

Cheers!

 

Totally forgot ester formation! Some of the dark fruit flavors in doppelbocks are formed by esterification during an extended lagering period. This is also why you don't see brewers lagering lighter beers that long, as you starting developing things not desirable in those styles.

 

I would agree. My first lager was a Dopplebock brewed at the end of December. I put it into bottles after 6-8 weeks from brewday (sat in the garage in Jan-Feb before packaging). "Lagered" it in the bottles (sat in garage in bottles all Spring [and Summer too]***). Won first place in May at a comp against some fairly medaled lager brewers, took 2nd the following February. I have also lagered a CAP in bottles (in the fridge) post 3 week primary and D-Rest.

***It worked, but I wouldn't ever recommend it. I only keg my lagers now, and leave in the fridge for a few weeks before drinking (start sampling them way too soon though).

 

Just the right time for this post, as I have just finished the "maturation" phase of my first lager and was looking to reconfirm what I was doing. Thanks to those above for all the information.

I do have some questions about the "shocking" of the yeast by dropping the temperature. Is there any sort of guide as to what the limit is for decrease to shock/not shock the yeast? Yes, I know it's not as black-white as that, but any info would be great as I've seen quite a bit of contradictory figures thrown around. Does this temperature decrease depend on the temperatures we're talking about - e.g. is it the same if you are dropping from 8C to 0C (46F to 32F) compared to 12C to 4C (54F to 40F)? Also, if one does "shock" the yeast, do they eventually recover again or do they just shut down until the temperature warms up?

 

If the yeast is finished with attenuation and cleanup, you can't (with a fridge) lower the temperature fast enough to hurt anything. The yeast will simply go dormant, which is fine if they were done. I usually cold crash my lagers after a generous D-Rest.