Lager ferm temp & diacetyl rest

[Bassman2003]

#1 - Vale71 is right on target here, letting the yeast clean up after itself is a homebrew myth in my opinion. There are reasons for keeping yeast alive and around which are related to fermentation and carbonation. The main point being dead or dormant yeast cells do not do anything. So once the fermentable food runs out in your beer the yeast literally drop out of the picture. Whatever cleanup they do, they do as they are eating and active. So leaving beer in the primary for a month does not accomplish much other than more time for everything to drop out.

It is such a simple concept that it gets overlooked. The most important thing about aging is gravity causing all of the "stuff" to drop out of the beer. Seriously. That's pretty much what lagering is - colder temps speed up the dropping out of "stuff" to the bottom of the vessel which gets left behind.

I have always noticed when I drink a beer young and it is not totally clear that the flavor is kind of muddy. Once it drops bright the flavors are more defined and the beer tastes a lot better. Very simple and not magic from the yeast.

#2 - Spunding. This is where you transfer fermenting beer with about 1 Plato left in fermentation to capture the CO2. This is a way to naturally carbonate your beer. The spunding valve is a device that lets you set what pressure to hold and everything above that gets released. So when I spund I transfer from my primary into a keg, put the spunding valve on and let the beer finish in the keg. When I go to serve or lager the beer it gets put in the fridge and is ready to go with carbonation.

This is where the slow cold crash comes into effect as you do not want to put your yeast to sleep if you still want them to ferment and create CO2 for carbonation.

#3 - Starters. I pressure can 1.070 wort in mason jars. When I make a starter I add a bottled water amount to make a 2 liter starter. For ales I will make the night before and pitch the entire thing at high krausen. For lagers I let it ferment out, put in the fridge, siphon off and then add another 2L of wort and repeat the siphon routine. The best case scenario is to double the size of the second starter (4L) but I do not think I can put 4L in my starter container. Anyway, this is with one yeast pack to begin with. After all of this, I am still under the best case scenario for lager pitch rates. But I do not want to buy multiple packs so my ferment goes a bit longer.

Hope this helps!

 

[Vale71]

#1 - Vale71 is right on target here, letting the yeast clean up after itself is a homebrew myth in my opinion. There are reasons for keeping yeast alive and around which are related to fermentation and carbonation. The main point being dead or dormant yeast cells do not do anything. So once the fermentable food runs out in your beer the yeast literally drop out of the picture. Whatever cleanup they do, they do as they are eating and active. So leaving beer in the primary for a month does not accomplish much other than more time for everything to drop out.

It is such a simple concept that it gets overlooked. The most important thing about aging is gravity causing all of the "stuff" to drop out of the beer. Seriously. That's pretty much what lagering is - colder temps speed up the dropping out of "stuff" to the bottom of the vessel which gets left behind.

I have always noticed when I drink a beer young and it is not totally clear that the flavor is kind of muddy. Once it drops bright the flavors are more defined and the beer tastes a lot better. Very simple and not magic from the yeast.

I'm sorry but I never said that and you're just projecting your (mostly) wrong assumptions on others (me). Yeast that is still in suspension has residual metabolic activity long after all fermentables have been exhausted by primary fermentation. Yeast has energy reserves that allow it to keep going even without primary nourishment (much like we don't drop dead the minute we stop eating) and will absorb and metabolize lots of substances from wort besides simple sugars in an attempt to postpone cell death as long as possible. This residual (primarily reducing) metabolism plays a very important role in beer maturation, both in a homebrew setting as well as in an industrial setting. The only difference is that the industry relies on very expensive and sophisticated lab measurements to drive the process whereas a homebrewer relies on trial and error and experience.

 

[cactusgarrett]

letting the yeast clean up after itself is a homebrew myth in my opinion. There are reasons for keeping yeast alive and around which are related to fermentation and carbonation. The main point being dead or dormant yeast cells do not do anything. So once the fermentable food runs out in your beer the yeast literally drop out of the picture. Whatever cleanup they do, they do as they are eating and active. So leaving beer in the primary for a month does not accomplish much other than more time for everything to drop out.

Respectfully, I couldn't disagree with this more. What's the point of aging a beer (especially big beers) then? What is the rationale behind beers improving with aging, post-fermentation, then?

 

[Bassman2003]

No worries. I am sorry if I mis-interpreted what you said. I have heard and read stuff on this topic all over the map. When one looks at commercial operations they have much shorter times for most processes which leaves no time for the extended activity homebrewer's are expecting see. I listened to a Beersmith podcast with Charlie Bamforth who had the position that the positive effects of aging are achieved in a shorter time than traditionally thought. Overall it seems to me that extended beer aging is in the category as needing a strong boil.

Look, I am not saying to avoid aging beer nor to dump the primary within a short time of saying "it's done!" What I am saying is that more and more evidence is appearing that a lot of homebrew practices are being called in question.

But, Vale71, a few posts ago you just wrote that "Yeast that has dropped and is laying at the bottom of the bucket has zero contact with the beer and hence plays no role whatsoever in maturation." Well my opinion is that by the time of the usual homebrew 'wait three days to have the same gravity reading then it's done' the active yeasts in suspension have enough time to clean up. The rest have fallen and apply to your quote. How is that different from what you know?

I asked the question that nobody answered - If the yeast do perform this cleanup, how long does it take? If a primary fermentation can be finished in as little as three days, surely the cleanup would not take as long?

Not being an ass here but this stuff is in a huge gray area and I think it is good to discuss it.

 

[cactusgarrett]

What I am saying is that more and more evidence is appearing that a lot of homebrew practices are being called in question.

This i am TOTALLY on board with. I abhor, in life in general, when people fall back on "that's the way we've always done it."

I asked the question that nobody answered - If the yeast do perform this cleanup, how long does it take? If a primary fermentation can be finished in as little as three days, surely the cleanup would not take as long?

I don't think anyone answered it because it was too hypothetical. That's like asking "When's my beer done/ready?" What's the definition of "done?". Seems like there are two approaches:

• One could bust out the lab equipment and say "byproduct X is removed within Y days of formation, blah blah blah", or
• One could rely more on the qualitative aspect and say "cleanup is done when i no longer taste the byproduct/off-flavor." But then you get the whole 'taste is relative' issue. Talk about a gray area!

 

[beerisyummy]

As long as yeast is "alive" autolysis is not a concern. Autolysis is a natural decomposition process akin to the decomposition of a corpse. Cavities in the cell (vacuoles) hold enzymes whose sole role is to destroy proteins, basically waste management facilities. As long as the cell is active these cavities will remain intact and the enzymes will not "run loose" in the cell. Once the cell "dies" vacuoles burst and the cell structure will be destroyed by the enzymes. Yeast that has dropped has ceased all activity and will be more likely to undergo this form of cell "death". But of course even yeast in suspension can be affected although not as much, which is why filtered beer is more stable and has a longer shelf life than unfiltered.

Okay, yes that sounds right. So to get back to your earlier statement, it sounds like you are saying that any "clean-up" work done by yeast after fermentation proper is done by yeast in suspension rather than in the cake. Right?

 

[Vale71]

Okay, yes that sounds right. So to get back to your earlier statement, it sounds like you are saying that any "clean-up" work done by yeast after fermentation proper is done by yeast in suspension rather than in the cake. Right?

Actually, any work that is performed by yeast is performed by the cells that are in suspension. This includes primary fermentation too. Any yeast that collects on the bottom can be dumped (if technically capable) with no delay and no regrets.

 

[Vale71]

But, Vale71, a few posts ago you just wrote that "Yeast that has dropped and is laying at the bottom of the bucket has zero contact with the beer and hence plays no role whatsoever in maturation." Well my opinion is that by the time of the usual homebrew 'wait three days to have the same gravity reading then it's done' the active yeasts in suspension have enough time to clean up. The rest have fallen and apply to your quote. How is that different from what you know?

I asked the question that nobody answered - If the yeast do perform this cleanup, how long does it take? If a primary fermentation can be finished in as little as three days, surely the cleanup would not take as long?

Commercial breweries can only dream of three-days maturation times and believe me, they've expended a lot of effort in order to shorten processing times as much as possible. Your question is too generic to be answerable. There are so many variables starting with ale vs. lager, yeast strain, pitch rate, oxygenation, OG, size and shape of vessel(s), temperature profile that can make minimum maturation times swing between just a week (possible with very light British ales) to several months with Doppelbock-type lagers fermented traditionally (cold fermentation, cold maturation).

 

[beerisyummy]

I just checked my copy of White & Zainasheff Yeast. "Clean-up" is not in the index lol.

However the following passage is relevant to much of this discussion:

"Many people ask if they can crash the beer temperature, or should they lower it slowly? The concern comes over sending the yeast into a dormant state, thereby preventing them from continuing the uptake of compounds during the long cold-conditioning period. The reality is that very little happens once you take the yeast below 40° F ... If you want the yeast to be active and to carry on reduction of fermentation by-products, it happens much faster at higher temperatures. As far as yeast activity goes, crashing the temperature or lowering it slowly makes little flavor difference if you are dropping the beer below 40° F ... However, very rapid reduction in temperature (less than 6 hours) at the end of fermentation can cause the yeast to excrete more ester compounds instead of retaining them." [emphases mine]

This would seem to be an argument for a longer diacetyl rest, and maybe slow lowering of temp at least to 40° and then you could crash the rest of the way down to 32°

Opinions?

 

[Vale71]

When doing lagers I always maintain fermentation temperature for three days after FG has been reached and then lower it by exactly 0,8°C per day. Make of that what you will...

 

[Bassman2003]

The reason I ask the generic question is without being able to quantify it how do we know how to do it?

Also, are aging and maturation the same thing? Is yeast always a part of the aging and/or maturation process or is it only really involved in maturation. What are we really doing when we age a beer?

My comments have largely been about after you leave the primary, or at least at the end of primary fermentation. Real lagering takes place below 40f, so not much yeast involvement if you take the yeast book's view. Hence it seems to be more about dropping stuff out than anything else. But a lot of beer at the homebrew level is not lagered. So lets take a typical pale ale for an example:

Primary fermentation lasts for 3-10 days based upon your pitch size. Commercially this would be 3-5 days for sure. So common practice as stated by Vale71 is fermentation + three days then lowering the temp for aging/maturing. As we lower the temps the yeast will become less and less a part of the picture. If one cold crashed the yeast would really be out of the picture pretty quickly. So those three days after primary fermentation seem like the best shot of yeast cleanup. After the beer gets cold, are you saying there is still yeast contributing to add or remove flavors? I tend to think it is more about gravity at this point. But that is why it is good to discuss.

 

[Dland]

Interesting stuff, one could get confused if one tried to follow all the different written advice ;}.

Before I started spunding, I heated up for D rest in primary(conical), and waiting 3 days after activity mostly stops seems about right, now I keg before D rest and spund at the same time.

Not sure about effect yeast on bottom of primary before crashing, but with conicals I can do trub dumps, and do, at least twice usually, and it seems to help.

I don't spend much time reading theory, but spend a lot of time making lagers. I have found my lagers seemed to improve noticeably when I started following a couple basic tenets:

Any changes in temp, such as ramping up for D rest or general "clean up"(*) seem best to do gradually, the same for ramping down for crash. Too fast a ramp up or down sometimes stops the yeast from working, especially at cooler temps, near the end of fermentation when activity has slowed.

Lagers tend to improve for at least 4-8 setting cold (lagering) after cold crash. The aging process after crash has little or nothing to do with the (now dropped) yeast. I use kegs and spund before crashing, but if I bottled, I'd age cold in bottles after carbing.

(*) Seems like cold fermented lagers sometimes clean up some during D rest process even if they did not really have a diacetyl problem.

 

[beerisyummy]

This was a very informative thread, thanks to all the participants.

So if I can clarify (pun intended) part of the discussion - it would seem that the positive effect I perceive (or imagine, lol) from leaving my ales in the primary for four weeks is in part from allowing more yeast to drop, and perhaps in part to allowing the remaining viable yeast time to "clean up." Point of clarification (ha) here would be that the yeast that are doing the actual "cleaning" are in suspension and not in the cake. Works for me, appeals to my natural laziness in not having to rack to secondary, and also no risk of infection from the transfer activity. Also - and this is not insignificant for me as brewing can be a time consuming hobby - It allows me to make a batch every four weeks like clockwork. Every brewing session I bottle the previous batch during the mash, and then celebrate at the end of the evening by tasting the previous-to-the-previous batch. I know you can do it faster, but I don't care, and I'm a believer in patience as an essential brewing ingredient.

As to lagers, I would identify with the "traditional" camp (in response to Bassman2003's remark "I think with the advent of quick and warm fermented lagers, when discussing lager brewing one needs to decide if you are in the traditional or new camp.") My inclination is to make a few lagers the "traditional" way before I look for short-cuts. So it seems sensible to me to raise the temp, after the first few days, gradually to 60°F or thereabouts, hold until fermentation is complete, drop gradually to 40° and then lager at 32°.

I didn't really get a reaction to this question, so if anyone wants to chime in please do. I still believe I should rack to a secondary after the first week or two of lagering. A total of 8-ish weeks on the yeast cake seems risky to me, even at 32°

Thanks y'all

 

[Jag75]

I didn't really get a reaction to this question, so if anyone wants to chime in please do. I still believe I should rack to a secondary after the first week or two of lagering. A total of 8-ish weeks on the yeast cake seems risky to me, even at 32°
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once you've done the diacetyl rest and you've went back down to 30's then keg or bottle . My Lagers sit in the fermenter for 3 to 4 weeks . It depends on how fast the fermentation takes . Then I transfer to a keg for Lagering. No reason to move to a secondary for lagering .

 

[couchsending]

If you want to transfer to secondary I would do so with at least 1 plato left in fermentation. You will leave behind a sizable amount of yeast. If you’re bottling and don’t have Co2 handy I would actually bottle spund. So transfer to your bottles with that 1 plato to go. You’ll end up with a decent amount of yeast in the bottle but it’ll do a better job of protecting the beer from oxygen.

 

[beerisyummy]

Ok so 1 Plato is 1.004 SG if I read the right conversion table. Seems to me that level of precision (referring to spunding) depends on some experience with how a particular yeast (even recipe) performs, and also would need a couple/three hydrometer readings, to which I have a previously stated aversion.

I'm not a kegger. But should I consider bottling from the primary and THEN lagering in the bottles? Will the bottles carbonate at lagering temp though? Or do I let the bottles carbonate at cellar temp and then lager them? On the other hand should I worry about whether there will be enough viable yeast to produce bottle carbonation after an extended lagering period in the fermentor?

I'm so confused

 

[Nate R]

Hi all. This may not be the best thread for this, but i like the discussion.
I am doing a bohemian pilsner with white labs wlp800 pilsner lager yeast.
I read that suggested temp was 50f for 4-6 weeks. Then suggested to warm up for dialaticl (spelling) rest for a week.

After reading these posts, will i need such a long time for primary (4-6 weeks as i read)? Should i jusy use gravity measurements to gauge?

Also, after primary... can i rack to a keg for conditioning? I assume the beer will taste better after being rested cold for a bit. Say 2 to 4 weeks at about 38 or so (the temp i keep my keezer at)?

I dont have glycol for my cf5 conical... using an ice chest with frozen water bottles for the cooling source. Does great keeping it at 50 but not sure how cold i can get it to crash.

Final question- should i cold crash this? When in the process??

Thanks all. Sorry if i hijacked this thread.

 

[Jag75]

@Nate R . Yes you should use gravity readings. I pitch the yeast and around day 7 I check the gravity . If gravity is 75% done I turn the temp up about 4 degrees a day until it hits 66 . I leave at 66 for 3 days then I go back down in temp each day by 4 degrees until I get to 38. I check my gravity and seeing that's its complete I keg and put on co2 .

 

[couchsending]

Ok so 1 Plato is 1.004 SG if I read the right conversion table. Seems to me that level of precision (referring to spunding) depends on some experience with how a particular yeast (even recipe) performs, and also would need a couple/three hydrometer readings, to which I have a previously stated aversion.

I'm not a kegger. But should I consider bottling from the primary and THEN lagering in the bottles? Will the bottles carbonate at lagering temp though? Or do I let the bottles carbonate at cellar temp and then lager them? On the other hand should I worry about whether there will be enough viable yeast to produce bottle carbonation after an extended lagering period in the fermentor?

I'm so confused

You can do what’s called a forced ferment test... after a day or two pull a sample of yeast and let it ferment at room temps, ideally on a stir plate but if you don’t have one it’s not a big deal. It will ferment faster than the much colder fermentation and you will be able to determine what gravity the beer will finish at. When you’re .5-.75 plato from FG transfer to bottles. You can keep them at 50 or raise them up to room temp, whatever you’d like to do. If you bump them up to room temp then it’s not as critical to slowly crash them. Then just lager them in the bottle and you’re good to go.

It might take a little practice to get it perfect but it should work no problem. Just use heavy glass at first until you’re very confident in everything. I wouldn’t try it with normal glass bottles to begin with.

 

[Vale71]

You can do what’s called a forced ferment test... after a day or two pull a sample of yeast and let it ferment at room temps, ideally on a stir plate but if you don’t have one it’s not a big deal. It will ferment faster than the much colder fermentation and you will be able to determine what gravity the beer will finish at. When you’re 1-1.5 plato from FG transfer to bottles. You can keep them at 50 or raise them up to room temp, whatever you’d like to do. If you bump them up to room temp then it’s not as critical to slowly crash them. Then just lager them in the bottle and you’re good to go.

It might take a little practice to get it perfect but it should work no problem.

1.0 to 1.5 Plato is 10 to 15 grams of sugars per kilogram of wort. This is 3 to 4 times the usual priming sugar amount and will guarantee serious overcarbonation, possibly bottle bombs. Why are you giving such stupid advice as if it were common practice?

 

[ESBrewer]

^Based on some calculators, I wouldn't say that 10g/liter is 3 times the normal. But it is about the high end of lager beer if we think that some co2 is released during a proper diacetyl rest at elevated temperature. But I don't know how reliable this method would be. Like couchsending says it may take some practice to get it right..+ an accurate hydrometer & measurements. And 1.5P definitely sounds too much (given that it eventually ferments in the bottles to the same extent as it does during the test).

 

[Vale71]

^Based on some calculators, I wouldn't say that 10g/liter (extract is not 100% fermentable) guarantees overcarbonation. It is about right for an average lager beer if we think that some co2 is released during a proper diacetyl rest at elevated temperature. But I don't know how reliable this method would be. Like couchsending says it may take some practice to get it right..+ an accurate hydrometer & measurements.

If you are 1.0-1.5°P above FG that means you have 10-15 grams of 100% fermentable extract. If that is not the case then you also don't know what your FG really is and are basically shooting in the dark. 15 grams of sugar will add over 3 vols of CO2 which is already more than what most people's target carbonation is, if you already have around 2 vols in the beer that will give you a whopping 5 vols total or possibly more and that is only if your measurements are really accurate and you have determined your FG properly. If the latter is not the case then who knows where your bottles will end up with regards to carbonation, you're basically playing Russian roulette with them.
Spunding in the bottle can get really dangerous, I would be a bit more careful giving such advice especially if your technical knowledge is so vague.

 

[ESBrewer]

Yes that was my mistake about the fermentability and I just made a correction, but I still don't think 1 P is 3 times the normal amount. I agree that it would be risky to do it that way so not recommended.

 

[ebbelwoi]

So if I ferment a lager at say 60, 62, 64 degrees, and I don't want to open the fermenter to check for diacetyl, do I need to do a diacetyl rest? This is the question I was hoping would get answered. I got kinda lost in the discussion a while back.

 

[ESBrewer]

I think diacetyl depends on several factors and the only way to know for sure is to taste the final product. But doing a rest at 65-68F is often recommended, because if there is diacetyl (or precursor) in the final product, it takes a long time to reduce it at cold lagering temperature. There are many ways to do the rest but you could go up to 65-68F (more or less rapidly, breweries tend to change the temperatures slowly) for two or three days and then lager. Or you could leave it for a little bit longer period at 60F. Diacetyl is reduced even at lower temperatures but it will take exponentially longer. You can also proceed to lagering straight away and see whether it works in your case or not. Typically, lagers are fermented at low 50s so in this sense your fementation temp is rather high. It will probably help scavenge some diacetyl towards the end of fermentation but it may also have some negative effects in the beginning of the fermentation (won't say too much about this cause I am no lager yeast expert).

 

[couchsending]

Yes my bad. I should have said .5-1 plato, not 1-1.5 plato. Obviously a lot of factors here. I'd use heavy glass regardless unless you're very confident. Degassing samples and using a finishing hydrometer is also rather important.

Here's a link to the calculations that I should have referenced, (and looked at first)

http://www.lowoxygenbrewing.com/wp-content/uploads/2016/11/Bottle-Spunding.pdf

Plenty of conversation online about it as well.

Went back and edited my first post for safety purposes.

 

[beerisyummy]

Typically, lagers are fermented at low 50s so in this sense your fementation temp is rather high.

Again, I'm a beginning lagerer but I haven't seen any lager yeast strains that recommend fermentation temp as high as 60.

In my lager-in-question, my WY2206 fermented very enthusiastically at 50°

 

[beerisyummy]

But wow, look at this article from the horse's mouth itself:

http://wyeastlab.com/lager-brewing

It's slightly but significantly different from much of the opining on this thread.

Primary ferm 48 - 58°
Secondary ferm 39 - 41°, slow drop to
Lagering 33 - 34° 1 - 4 weeks

No mention of a "diacetyl rest."

 

[beerisyummy]

And in this article John Oliver does recommend a diacetyl rest - of 50 - 55° !!!
He also recommends a two-stage approach: "Most lagers really develop their clean, finished character through an extended conditioning period of several weeks at temperatures on the low end of the yeast strain’s performance range. Racking into a secondary fermenter allows this process to take place without creating any off-flavors or aromas." (I'm pretty sure this is where I got that idea.)

https://byo.com/article/10-keys-to-great-lager/

Wow, we are really all over the map on this, aren't we?

 

[beerisyummy]

So I think, based on what I intended to do originally, slightly modified as a result of this fabulous discussion, I'm going to adopt this as my standard lagering procedure:

PITCH YEAST (big starter)

FERMENT AT 50° FOR 5-6 DAYS (begin temp raise sooner if bubbling stops increasing)

RAISE TEMP 2° PER DAY TO 60° (5 days)

REST FOR 5 DAYS

(take hydrometer reading)

LOWER TEMP 4° PER DAY TO 40° (5 days)

CRASH TEMP TO 32°

(about 3 weeks)

LAGER FOR 1 WEEK

TRANSFER TO SECONDARY FOR ADDITIONAL LAGERING

I'll let you know how it goes...