Lagering in a Keg

Crash cooling stresses yeast causing them to do various things one of which is floculate and another of which is to release esters. Both of these are advantageous in ale brewing (a subject about which I don't really know much) and, AFAIK, quick cooling is standard practice. While the ester flavors may be considered off in lagers they wouldn't be in an ale so I wouldn't worry about your IPA.

hey aj - lots of great info in this thread -- thanks!

just wondering if you have done experimentation with lagering temperature and at what temp do you usually lager?

That is one thing I call a myth. Here it is out of Brewing Science and Practice. This is refering to the first drop to 5C--the one Dan's schedules omit the slow drop from.

A sudden fall in temperature must be avoided or the shock may induce the yeast to excrete protease enzymes that could be detrimental to foam stability. This cooling may take from two to nine days.

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I don't like the way word 'must' is used with 'may' and 'could'. Other text I have don't even mention it's effects on foam. I'm going to call this myth. I've not had the alleged problem. Perhaps it's strain dependent.

I simply do not believe the cold maturation produces a better beer.

Another myths in that book and other places (even in Dan Gordon's article) is the need for complete trub removal. It's been proven that it speeds fermentation. Dr. Bamforth said it's not known if its because of it's nutritional value or just because makes nucleation sites for CO2. There is a study by Weihenstephan in a pdf. As I recall chemical analysis showed little difference.

There are more myths in there too, IMO backed by bad science.

I generally ferment at 46 - 48 °F and when gas evolution slows and gravity is within a couple °P of what I expect to be terminal I start the 1 °/day slide down to close to freezing. That takes a week or 2. I then hold it at near freezing for a couple of weeks more (with the duration determined more by when it is convenient for me to transfer to kegs than strict adherence to a plan) and then transfer to kegs. The design of my fermentors is such that the chill bands keep the yeast in suspension even at near freezing and while I at first thought that was a disadvantage (and thought about changing the glycol flow) came to realize that it is an advantage as I definitely wand yeast in the kegs. The kegs go into a cooler that keeps average temperature around 36 °F. I start drinking them the day they go into the cooler and keep doing so until the last keg is emptied which can be from 6 months to over a year depending on demands for beer (parties, son's friends visits etc.). For the first week or 2 the beer is usually drinkable but has lots of green character. Then suddenly one day a couple of weeks in it turns over night (drops pretty clear and jungbuket is gone) and is declared ready to drink. That day is the beginning of the fascinating gradualy changing life cycle of the beer and the happiest day in the brewer's life. My Helles just hit that point yesterday so I'm anxiously awaiting beer o'clock today.

Note no diacetyl rest. One isn't necessary. The diacetyl level is close to threshold i.e. there is just enough to give Pilsners that Pilsner character. I think I mentioned earlier that I used to measure it but stopped doing so as the answer always came out the same (and I can't find my CO2 flow meter).

In a commercial operation when the beer is "ready to drink" off it goes to have the yeast filterd/centrifuged out and thenceforth out the door. In the way I do it they stay on the yeast for the life of the beer. I realize that that would not be practical for a commercial operation but I have mentioned before the benefits of having it stay on the yeast while it is being consumed. It keeps it fresh for a long time.

I can't claim to have done any experimentation which would show that lowering 1 °C/day is better or worse than 1 °F/day or that lagering at 35°F is better than at 37 °F. I've sort of stumbled on this arrangement over time and, as I am serving lagering beer the choice of lagering temperature is driven by the need to compromise a bit i.e. not serve ice cold beer but still allow proper lagering to take place plus if I crank the temperature down in the cold room I'd have to worry about freezing of the evaporator at the bottom of its cycle and I don't have defrosting equipment. In short I have stumbled on my practices mostly through experience. I'm very pleased with the beers I'm getting but am always looking for ways to make it even better. Maybe I'll crank that lagering controller down a degree or 2.

Malticulous said:

Perhaps it's strain dependent.

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Perhaps it is in which case it wouldn't be a myth.

This is from Handbook of Brewing. This chapter is by James H. Munroe of AB/inbev. It's the best book on brewing that I've read.

Historically, lagering was necessitated by the absence of refrigeration, the need to remove yeast, and the need to control the level of carbonation in beer. Consequently, lager beer was brewed during the colder months and stored in iced caves for long periods of time. Cutting ice for summer storage of beer was well known prior to the advent of refrigeration. Primary fermentation was usually done at or below 10C. The resulting beer, containing about 1% fermentable extract, was then transferred to a cold storage cellar along with some suspended yeast. The yeast would assimilate any oxygen picked up during transfer into storage, thus eliminating a potential oxidative flavor problem. Secondary fermentation of the remaining fermentable extract proceeds increasingly slowly while the beer gradually cools over several days. Because CO2 is more soluble at lower temperatures, the brewer could readily obtain elevated levels of carbonation. Total storage time was up to about 50 days at 0C. The long, cold storage allowed not only the settling of the remaining yeast, but also the settling of haze-forming material. Extended storage times have been promoted as giving superior flavor maturation. Modern thinking is that long, cold aging is not necessary if the process provides for the elimination of VDKs, their precursors, and other compounds responsible for green beer flavors in immature beer.

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[Edit] OK, I posted a response and started feeling guilty because it was game playing and not contributing to anyone's knowledge of brewing but then I realized that what we are dealing with here is what is called "cognitive bias" and everyone, no matter what he says, is subject to it. This can effect one's brewing decisions and it can effect one's perception of what he is tasting, smelling etc. That is why organoleptic tests are done double blind (if the investigators are really after the truth). Malticulous has announced that he will never believe that cold lagered beer could be better, by any criterion, than beer done by the more modern methods. This is an article of faith for him. Therefore, if he sees something that says it can, in his mind, that is "bad science" and/or he'll forget that he saw it. OTOH if he sees something that supports his belief he will remember that. We all do this. I do it. I firmly believe that properly lagered triple decocted lagers taste better than infusion mashed, fast matured beers and will definitely prefer such a beer if I know that's how it is made. But I'm smart enough to know that cognitive bias is at play and thus haven't the temerity to state as fact that those beers are better for even in the most restrictive definition of optimality, my personal preference, cognitive bias is at work (the exception to this is when looking at a brewery's P&L statement - the investors all agree what the optimality criterion is there!). The relevance of this to brewing should be clear and, as I said before, is why not only taste panel members but those who serve them are kept in the dark about what they are tasting. So there - that does, I hope, add to the collective brewing knowledge. Keep this in mind when you taste and especially keep it in mind before talking to your investment adviser or going to the polls!

Cognitive bias also influences what we see/take in and how we interpret it. For example, in the quote from HoB, the key phrase is

Modern thinking is that long, cold aging is not necessary if the process provides for the elimination of VDKs, their precursors, and other compounds responsible for green beer flavors in immature beer.

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The key words are "if" and "other". Note that this author works for the world's largest brewing company and they don't do traditional lagering (don't really know that but am 6 or 7 9's certain). So it's pretty clear where his bias would lie. But he is clearly aware of it and has worded his statement such that neither he, nor are we, his readers, victim to it. He does not say that cold aging is not necessary nor that it results in better or worse beer but only that current thinking is that you don't have to do it IF you can get the VDK's and other greening compounds out. That's a big if. It's easy enough to measure VDK and acetolactate and acetaldehyde but it's the myriad (and there must be hundreds) of other compounds that produce the nuanced flavors that lend to or take away from the complexity that differentiates "acceptable" from "good" and good from "great" beers. I don't think anyone will accuse Inbev of producing complex beers. And yet the author clearly understands this. He has carefully constructed his paragraph in a way that reflects an open mind or at least knows better than to state as fact that which he can't support (I prefer to think its the former). If completely blinded by cognitive bias against the traditional methods you would read this quoted sentence as "Fast lagering is better". If less blinded you might read it "Traditional lagering is no better". IOW the subjunctive clause may not be seen at all. My personal thought is, cynical bastard that I am, that the sentence would reflect the truth more accurately if it read "Modern thinking is that long, cold aging is not necessary if the beer sells." If I were invested in Inbev (AFAIK I'm not) that would be all I'd care about.

Malticulous said:

... Handbook of Brewing. It's the best book on brewing that I've read.

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It probably should be on most brewers bookshelves but it a far cry, IMO, from being the best out there. It suffers from that lack of cohesion that all books which are collaborative efforts (i.e. chapters by several authors) do. I don't know anything about Priest but I've met Graham Stewart and he is a fine brewer and gentleman IMO. So I don't want to sound too negative not only out of respect for Stewart but because the book is supposed to be a handbook - not a text book. The main criticism I have is that it is short on the science, again perhaps justified by its intended audience and much too slanted towards British brewing practices. The first place I look in a brewing book is the water chapter. I think Moll's water chapter in the edition edited by Hardwick was better. In this edition the first profile I check is unbalanced by 3 mEq/L which means no one checked for this. That's pretty bad for a book that costs this much.

There is much more science in Hough, Briggs, Stevens and Young and its replacement, Briggs, Boulton, Brookes and Stevens but I have to say with this pair, as with HoB the newer editions are a bit of a ripoff given the amount of new material relative to the older editions and the huge cost of modern textbooks.

For the continental perspective Kunze is sort of the HoB of German brewing i.e. not much science - lots of pictures of mash tuns. The font of information of lager brewing is, of course, Narziß buf I don't think it's available in English. And there isn't one single diagram or graph in it!

Saving the best for last: DeClerck's 2 volume set. Cerainly dated but I think readers will gain a more complete understanding of brewing fundamentals from these books than any of the others.

There are of course other texts some of them specialized such as Briggs on Malt, Neve on hops, Boulton and Quain on yeast and White and Zainasheff on yeast.

For kicks I decided to listen to a couple Brewing Network shows with Dan Gordon. In particular the show he did in 2006 mentioned a few things in their process I gathered...

Propagate yeast at 9C, Pitch into 7C wort and let rise to ferment at 9C for about a week until it gets 1P above expected FG. Then lowers the temp to 6C for a diacetyl rest for 3-4 days (doesn't mention how fast). Then they lowering at 1 degree/day to 0C to lager 5 weeks. Said if you get it to -1 or -2C for the last couple weeks it will improve head retention according to a Weihenstephan study.

I just remembered he spoke at NHC this year... The PDF from his presentation at NHC this year has some process and recipe info.

ajdelange said:

I doubt you will find many big (or small or medium) breweries that use this method any more.

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I guess I have to take that back based on those slides which were quite interesting. Not only does GB use triple decoction mashing in some beers but they do traditional lagering as well.

I don't know much about GB and have been in few of their stores and was never much impressed with their beers. I don't know if the following illustrates cognitive bias or the effects of care in the brewing process or both. The head brewer from one of the local GBs used to come over here and drink my Pils and Vienna (or actually anything I'd give him). And of course we'd talk process but it must have been mine, not his, or we must have drunk a lot of beer because if I knew any of what was on those slides before I don't remember it. But I do remember that he was extremely dedicated, brewing was his life (though he has a lovely wife and child and I don't mean to imply that he neglected them) and his beer was exceptionally good - both relative to other GB shops I'd been in and in absolute terms. In my opinion.

Now there are several reasons why I could conclude this.

1. Cognitive bias based on personal approval of this fellow's approach to the holy art
2. Cognitive bias based on just liking this guy and hoping he would be successful
3. Cognitive bias based on the fact that his Pils tasted a lot like my Pils
4. Triple decoction mashing and traditional lagering really make better beer if done by a skilled brewer.
5. Combinations of the above.

I did notice improvement in head and head retention as I moved to the process I am using now and have seen statements in the literature to the effect that this is associated with traditionally lagered beers but never attributed it to the gradual lowering of temperature. I always thought it was my masterful handling of the protein rest (that's a joke).

A little bit off topic, but what happens if you drop the temp down to 32-34 degrees and the global warming kicks in and you start having 50 degree days in Jan in MN!!!! I lager in my garage and regulate the temp with in floor heating. This is usually very easy when it's 10-20 degrees out. I had my latest lager all snuggled in at 34 degrees and bam we get 50 degree weather. Now my garage is fluctuating between 40-48 degrees. Is this going to cause any off flavored in my yummy Surlyfest clone?

flabyboy said:

A little bit off topic, but what happens if you drop the temp down to 32-34 degrees and the global warming kicks in and you start having 50 degree days in Jan in MN!!!!

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The opposite happened to me. We had a cold snap (as there has been a fair number of these in the last few years the alarmists have changed to the now more politically correct "climate change" but it is still George Busg's fault) a couple of weeks back and it got so cold in the brewery that the yeast I had working on a stout went to sleep too early and I only got an ADF of a bit over 60%. Dry this beer is not.

flabyboy said:

Now my garage is fluctuating between 40-48 degrees. Is this going to cause any off flavored in my yummy Surlyfest clone?

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Doubt it will cause a serious or even noticeable problem though it will probably taste a little different than it would have if the temp had stayed uniformly cold.

Unfortunately this place always preached a 4-5F drop per day in lagers, that's what i've been doing after the d-rest. I will definitely try this way as i'm about to go hog wild on the lagers in January and February. I will say that my cap's turn out really well, but if they can be improved upon, so be it.