Diacetyl Rest Question

[Ross]

Guys,

Done the searches & there seems to be conflicting views all over the place...

John Palmers book says wait till primary is all but finished before raising for 24 - 48 hrs, whereas on a recent online forum with Chris White (President of White labs) he says to remove when Gravity is at 1020 & rest for a week at ale temp.
Is there a general consensus of opinion on which way to go?

Also I've read in some posts to reduce temp a couple of degrees a day down to lagering temp & others that indicate it's not required?

Doing my first lager (Doc's Oktoberfest) with 2278 wyeast & wanting to get the best result possible - It's been down eight days, has a nice foamy krausen & currently 1030 - so up todate advice from an experienced lager brewer would be most welcome...

 

[Tony M]

Ross,
I have plenty of thoughts on the subject but little hard knowledge. I have made lots of lagers over the last couple of years and I now find myself doing the diacetal rest when the brew is half a dozen points short of finished. In my humble opinion, starting a five day rest a little more than half way thru the brew would diminish the lager characteristics that are being sought, for the fermentation would certainly finish in those five days. giving a brew half done at lager temp and 1/2 at ale temp.

 

[warrenlw63]

Ross,

Because I ferment in glass carboys I'm not overly scientific with my FG readings.

I start a diacetyl rest when the krausen has dropped and the beer looks like it is starting to fall bright. Say about 10 days or so after primary fermentation.

Then I just warm it up to about ale ferment temps (16-18c) for 2-3 days, rack and then slowly drop the temp about 5 degrees a day until I hit lagering temps.

Never had any detectable diacetyl in my finished beers. My gut feeling is you don't have to be strict about when you do it. So long as it's near enough to the end of primary fermentation and the beer's still on the primary yeast you should be OK.

That said if yeast pitching and/or early fermentation temps are high generally no amount of diacetyl rest will absorb the lot.

Warren -

 

[Doc]

Is there a general consensus of opinion on which way to go?

No

Doing my first lager (Doc's Oktoberfest) with 2278 wyeast & wanting to get the best result possible - It's been down eight days, has a nice foamy krausen & currently 1030 - so up todate advice from an experienced lager brewer would be most welcome...

[post="52077"][/post]​

Excellent Beer.
On the Oktoberfest (mine) when it hits 1.020 I raise the temp for a diacetyel rest for 48 hours.
Then back to lager fermentation temps for 24 hours, then as long as the SG is right to cold conditioning temps.

Beers,
Doc

 

[Asher]

Gday Ross

Your right, there are many differing opinions on how to conduct the perfect ferment..... I'll explain how I do it, but that's not to say its the only way (many ways to skin a cat). I've come up with my methods after reading lots of differing articles too, applying some of their methods and some of my own logic.... :blink:

A typical lager ferment runs as follows:
- Pitch yeast at around 20deg (also the temp my lager starters are fermented at )
- I let the beer sit at around 18 deg until the very first sign of krausen foam(usually within 12 hours - or the next morning), then cool gradually over the next 12-24 hours to desired fermentation temp - (Yeast are quite happy to be warmed up quickly but don't like being cooled down too quickly)
- When airlock activity is beginning to slow I turn off my fermenting freezer and let temp of fermentor rise naturally for the diacetyl rest. I never add any heat, just let the yeast activity produce its own heat. (temps usually get back up to around 18-20 deg). I usually just go airlock activity and the look of the krausen to decide when its time to do my rest, but I have taken the odd gravity reading here and its around 1.020.
- I leave the beer at this temp until fermentation has ceased (Usually 3-4 days).
- finally I reduce the temp of the primary by a few degrees a day until its around 10 deg, then transfer directly to a keg for cold conditioning....

Not sure if this helps, but may be a starting point for your own method...

Asher for now

 

[Ross]

Thanks guys,

Enough ideas there to keep me on the right track... :beer:

 

[Dunkel_Boy]

I do exactly what Asher does, except after the diacetyl rest (and once it's hit terminal gravity) I transfer it to secondary (hopefully glass soon!) and then slowly drop it down, and I keep going until it's around 1-2C. Best of luck!

By the way, slowly can either be done with the fridge thermostat set on the coldest and done in steps with your digital temp controller, or done in one step with the digital controller and with the fridge set to midway-warm... but I recommend the first way, until you know how your fridge behaves. You may not even be able to do it, but it makes it easier in the long run.

 

[Ross]

DB,

All my brews are controlled digitally by probes in the actual beer to
+/- half a degree - so temp adjust extremely easy... Also using a commercial freezer, so can drop temps pretty quick when needed - but looks like slow is the preferred method....Thanks..

 

[Dunkel_Boy]

Ross,
That sounds bloody accurate.
I was just suggesting that instead of setting the temp a few times, to slowly get the temp down from 18-20 down to 1-2, you can (if you know your fridge) just set it to 1-2 and it will take 48-72 hours to actually get down there... so you can basically walk away and forget about it. I suggest you be careful if you try it though.

 

[Ross]

DB,

It would drop in 24 hrs if i set it & walked away - Is this ok or is it better being stepped?... I'm guessing stepped...

 

[Dunkel_Boy]

Probably, yes.
I'm actually wondering if lagering is a function of the yeast, or if it's just temperature-dependant. If it depends on yeast, then it's essential to drop the temperature slowly, or in stages, down to 1-2C, as everybody does. But, since fermentation will be over at this stage (ideally, anyway) perhaps it's ok to chill it down quickly... of course it would shock the yeast out of suspension, but maybe that's not a bad thing.

 

[Ross]

DB,

that's one of the things that has got me puzzled - If chris white reccomends a week, i guess he's saying to totally complete the ferment at ale temp & therefore dropping quick should be good??

bugger this is difficult compared to ale... maybe JP will see this & give a tip...

 

[Dunkel_Boy]

Apparently the book Helles in the Classic Beer Styles series says that you need live yeast in suspension for lagering to properly work... it's a function of yeast and temperature.
So everybody can rest in peace knowing that slowly lowering the temp is good for their beer.

 

[jjpalmer]

Perhaps JP will see this and....remember that he completely forgot to STOP doing the diacetyl rest last week and ran out to the shed minutes ago to find water on the floor from the defrosted freezer! His socks can attest that the water was still wet and cold too! Bugger!

Well what can I say about diacetyl rests... I get most of my info from Chris since he is a friend of mine.
As I understand it, some yeasts require a diacetyl rest, some yeasts benefit from a diacetyl rest and some don't need one. And, some fermentations require one, some benefit, and some don't need it. ie. the necessity of a diacetyl rest can depend on your yeast and on your fermentation conditions.

I am doing one for this Vienna with WL OktoberfestMarzen yeast, but I have not done them several times in the past and not noticed a need for it. Other yeasts were Bavarian Lager, and Bohemian Lager...

HOW to do it? Well, I agree with DB, I wait until the krausen has started to fall, but still foamy, still bubbling, probably a few points to go, and then let it warm to 17C or so. And then I forget about it for several days....@#$%&*! No, I would only do it for 2-3 at the most. You shouldn't have to clean up very much. Obviously if you want a lager charactor you don't want to conduct a large part of the fermentation warm.

Ah, now I remember, Chris advocates starting the batch warm (to get a high repro rate I think, as well as ease of use to customers) and lowering the temp to primary fermetnation temperature, whereas I recommend chilling to fermentation temperature and then pitching so that there is not an initial warm/high diacetyl period in the ferment that the yeast have to clean up later. Now on the other hand, Chris says that diacetyl is not produced for the first 24?? hours or so, so it doesnt matter if you start warmer.... I will have to pin him down on that statement and get some details....

Good Brewing Mates,
John

 

[Ross]

- I leave the beer at this temp until fermentation has ceased (Usually 3-4 days).
- finally I reduce the temp of the primary by a few degrees a day until its around 10 deg, then transfer directly to a keg for cold conditioning....

Not sure if this helps, but may be a starting point for your own method...

Asher for now

[post="52107"][/post]​

Asher, Are you carbonating & then cold conditioning? As it appears the lagering needs to be done on the yeast?

JJpalmer,

How long lagering till it can be carbonated & kegged?

 

[jgriffin]

Ah, now I remember, Chris advocates starting the batch warm (to get a high repro rate I think, as well as ease of use to customers) and lowering the temp to primary fermetnation temperature, whereas I recommend chilling to fermentation temperature and then pitching so that there is not an initial warm/high diacetyl period in the ferment that the yeast have to clean up later. Now on the other hand, Chris says that diacetyl is not produced for the first 24?? hours or so, so it doesnt matter if you start warmer.... I will have to pin him down on that statement and get some details....

Good Brewing Mates,
John

[post="52443"][/post]​

See now this is where i get confused a bit. I've been told time and again the most important time to prevent off flavours in Ales is the first 24 hours where high temps cause everything from fruity esters to fuesel alcohols, yet people seem to promote starting lagers high and gradually dropping them?

 

[jjpalmer]

Ah, now I remember, Chris advocates starting the batch warm (to get a high repro rate I think, as well as ease of use to customers) and lowering the temp to primary fermetnation temperature, whereas I recommend chilling to fermentation temperature and then pitching so that there is not an initial warm/high diacetyl period in the ferment that the yeast have to clean up later. Now on the other hand, Chris says that diacetyl is not produced for the first 24?? hours or so, so it doesnt matter if you start warmer.... I will have to pin him down on that statement and get some details....

Good Brewing Mates,
John

[post="52443"][/post]​

See now this is where i get confused a bit. I've been told time and again the most important time to prevent off flavours in Ales is the first 24 hours where high temps cause everything from fruity esters to fuesel alcohols, yet people seem to promote starting lagers high and gradually dropping them?

[post="52452"][/post]​

Yes, this is why I don't advocate starting lagers warm and gradually cooling. I think (experts) say to go ahead and start warm because it is easier, and they don't want to complicate things for new lager brewers. They are probably thinking "oh, it won't make that much difference that they will notice..." but I think this is the wrong tactic.
Now maybe Chris White has some more data for me that will revise this premise, but my experience and that of several of my friends is that great lagers start out cold.
Newsflash: You don't need to pitch right away! If your sanitation is good you can put your wort in the fridge and chill it overnight to your fermentation temperature before pitching. Dave Logsden of Wyeast gave a presentation on brewery bacteria and yeast which demonstrated that the bacteria don't care if yeast are present or not, they still reproduce very very fast. So, initial sanitation, not immediate pitching is the key to a clean fermentation.
Cheers,
John

 

[sluggerdog]

Newsflash: You don't need to pitch right away! If your sanitation is good you can put your wort in the fridge and chill it overnight to your fermentation temperature before pitching. Dave Logsden of Wyeast gave a presentation on brewery bacteria and yeast which demonstrated that the bacteria don't care if yeast are present or not, they still reproduce very very fast. So, initial sanitation, not immediate pitching is the key to a clean fermentation.
Cheers,
John

[post="52513"][/post]​

I find this extremely interesting and great news for me! There has been a few times I have had a day to brew but my yeast wasn't ready so I had to put it off, this fixes that problem, thanks John.

My current brew seems to have had a little problem, it seems to be stuck, OG was 1048 and todays gravity is 1028 after 14 days at 10C (Wyeast Pilsen Yeast - 2007)

I have to move on with this brew as I have another ready to go into my fridge so I am planning on resting this for 5 days instead of the 2-3 and hopefully in this time it will lower the gravity enough and finish it off before I CC. Does anyone see anything wrong with this? I am kind f afraid that I will loose my lager chrematistics and/or get some off flavours?

Ideally I would rest it now then back into the fridge for another week at 10C but this is just not possible.

Thoughts? Cheers!

 

[Asher]

Asher, Are you carbonating & then cold conditioning? As it appears the lagering needs to be done on the yeast?

I transfer directly from my primary to kegs, then into a fridge (un-gassed) at around 2deg. The kegs then sit there until (or as long as I can wait anyway) they are ready to come on-line... So about a week before I'm going to need them I just plug the gas into them and let them carbonate over a week or so. I'm very careful when moving them to my serving fridge to not rouse any yeast that has settled. and here they sit until their empty..

Asher for now

 

[Ross]

thanks Asher, that makes sense.

Do others rack to a secondary for lagering, or do you leave on the primary for this stage?

i'll be glad to get back to ales - far less confusing...