Diacetyl Rest - How do I execute it?

[nabs478]

I have read all over this forum about diacetyl rests, and when to use them, but I cant find anywhere how to do it exactly, and none of the stuff I've read has been exactly applicable to me. I have a few questions...

1. How do you do it? I gather raising the temp a bit or something to get more yeast activity to eat the diacetyl?

2. I have a bock lagering at the moment, and I think that I didnt give it enough time in the primary at 10 C (50F) before trasnferring and dropping to 4 C (39F). It tastes awesome, best beer I've made I think, but it's still a little sweeter than I think it should be and has a flavour which I quite like but tastes just a little "buttery". So I wandering if I raise the temp, firstly what temp to, 10 C?, Will that be likely to make the beer dryer and remove that "buttery" flavour? Will it have any other effects?

Thanks.

Pip

 

[boo boo]

Your buttery taste won't go away now.
To do a diacetyl rest you need to wait until your ferment is about 2/3 the way
to terminal gravity. Raise the tempertures in your primary ( don't rack to secondary as you need the yeast in the primary to eat the diacetyl) to about 10f above your fermenting temperture. After you reach terminal gravity, rack to secondary and reduce to lagering temps by dropping 5f a day until at lagering temperture. Lager at 34 to 40f for a month or so.

 

[FireBrewer]

So I wandering if I raise the temp, firstly what temp to, 10 C?, Will that be likely to make the beer dryer and remove that "buttery" flavour? Will it have any other effects?

Once it's done fermenting (or nearly done), move it to an area of about 60-65°F. In a few days, draw off a sample using a sanitized turkey baster/whatever and taste it. If you still taste diacetyl (buttery, butterscotch, slickness, etc), keep it at the d-rest for a few more days. If not, return it to your lagering chamber and drop the temp as boo boo said.

A diacetyl rest will not dry out the beer. That's dictated by mash temp, amount of fermentables, and the attenuation of the yeast strain.

Cheers!

 

[TheJadedDog]

I don't mean to hijack your thread but I have a related question: do I need to wait for the krausen to fall before raising the temp to 60deg?

I brewed an Oktoberfest on the 11th and have been fermenting it between 48 and 50 deg. I was really hoping to rack and start lagering this weekend; I know it will need a diacetyl rest so I was going to bring it up to 60 starting tomorrow but it still has some krausen; can I bring the temp up anyway? (I don't know what the current SG is as I have not taken any readings on it since brew day).

 

[Yooper]

If you have krausen, you may or may not be at 75% done so you'll have to check the sg first, and then decide if/when to do the diacetyl rest.

I've had some lagers that haven't needed a d-rest, depending on the yeast strain used. Some always require one, some don't.

 

[TheJadedDog]

If you have krausen, you may or may not be at 75% done so you'll have to check the sg first, and then decide if/when to do the diacetyl rest.

I've had some lagers that haven't needed a d-rest, depending on the yeast strain used. Some always require one, some don't.

So if I understand you correctly, if I am at 75% (and need a diacetyl rest), I can bring the temp up even if there is still some krausen?

 

[FireBrewer]

So if I understand you correctly, if I am at 75% (and need a diacetyl rest), I can bring the temp up even if there is still some krausen?

Like Yooper Chick said, check the specific gravity. That will tell you where you are in terms of fermentation. If you pitched a low amount of yeast, your fermentation and d-rest are going to take longer.

 

[FlyingHorse]

Raise the tempertures in your primary ( don't rack to secondary as you need the yeast in the primary to eat the diacetyl)

As with many aspects of brewing, there appear to be different camps on this point:
http://brewingtechniques.com/library/backissues/issue2.1/miller.html

One thing to remember, if you incorporate a diacetyl rest, is to rack the beer - or in a unitank fermentation, draw off the yeast - before you allow the temperature to rise. This will help prevent the yeast dregs from autolyzing and giving a yeasty taint to the finished beer.

 

[Rhoobarb]

I always rack my lagers to secondary when they are close to fermenting out (~3/4, I'm not too picky) and let it sit at room temperature (usuallly ~67oF) for 48 hours, before cooling. So far, no diacetyl or 'butterscotchy' flavors.

 

[boo boo]

As with many aspects of brewing, there appear to be different camps on this point:
http://brewingtechniques.com/library/backissues/issue2.1/miller.html

With all due respect to Dave Miller, I disagree with the racking of the brew proir to the rest. Autolysis takes a lot longer than the time needed to do a diacetyl rest, even after the longer fermentation time. Remember, the yeast is still working and has not been shut down.
I would think that common sense would dictate that the more active yeast available to a wort to do the rest with wouild be better, faster.

I have been doing diacetyl rests on lagers for 2 years now and even with WY2308 strains, get no diacetyl detected. And I have entered comps without any judges commenting on any diacetyl tastes yet.

But if it works for you to do your rests differently, then who am I to say you shouldn't!

 

[FireBrewer]

With all due respect to Dave Miller, I disagree with the racking of the brew proir to the rest. Autolysis takes a lot longer than the time needed to do a diacetyl rest, even after the longer fermentation time. Remember, the yeast is still working and has not been shut down. I would think that common sense would dictate that the more active yeast available to a wort to do the rest with wouild be better, faster.

I agree. Dave Miller did a decent book but IMHO, New Brewing Lager Beer by Greg Noonan is much better (considered the authority on modern lager brewing this side of the Atlantic by many):

Post Kraeusen

Six to fourteen days (six to tten days is usual) after pitching, the foam head begins to diminish as CO2 production falls off. Extract reduction should slow dramatically and with a reasonably flocculant yeast strain the cell count will drop below ten million cells per milliliter.

If a diacetyl rest is being employed, force the temperature of the post-kraeusen ferment to rise to 55 to 60 degrees F (13 to 16 degrees C). After two days, lower the ambient temperature again, bringing the beer down to 38 to 40 degrees F (3 to 4 degrees C) at 3 to 5 degrees F (1 to 3 degrees C) per day.

When the extract drop slows to 0.5 degrees Plato (SG 1002) over twenty-four hours, the head will have completely fallen. Rack the beer into a secondary fermenter/lagering vessel.​

and

When the density drops to about 1.5 degrees Plato (SG 1006) above the target terminal gravity, the brewer raises the temperature of the post-kraeusen beer to 52 degrees F (11 degrees C) or higher, and holds that temperature for two to seven days for a diacetyl rest to reinvigorate the yeast culture so that it will metabolize diacetyl, removing it from solution.​

 

[dj_van_gilder]

I am on day two of my Diacetyl rest for an Octoberfest. I too discovered conflicting information about leaving it on the trub or racking to a secondary. I left it in the primary for day one, and I transfered it over to the secondary last night. The SG reading I took showed 1.023 @around 60-65 degrees.

 

[Yuri_Rage]

Your buttery taste won't go away now.

I disagree - a diacetyl rest is best done the way you describe it, but one can be accomplished at almost any point. Diacetyl is a volatile compound that will eventually evaporate out of your beer if you warm it to room temperature. Keep your beer at 68-72 degrees F for about 3 days, and you may have some success at eliminating that buttery flavor.

 

[boo boo]

I disagree - a diacetyl rest is best done the way you describe it, but one can be accomplished at almost any point. Diacetyl is a volatile compound that will eventually evaporate out of your beer if you warm it to room temperature. Keep your beer at 68-72 degrees F for about 3 days, and you may have some success at eliminating that buttery flavor.

The only way for it to go is by action of active yeast. You may have some success doing it this way as there is always some yeast in suspension.

 

[nabs478]

Thanks for all the info guys...but I guess I have missed the boat on this one.

My bock tastes a little "buttery", its not really a bad flavour, but I know its not meant to be like that. It is a 23L (5-6 Gallon) batch, and has been in the primary for 2 weeks at 10 C (50F) then secondary for four weeks at 3-4C (around 38F). Two days ago I added gelatin to clarify. I read on the packet that it needs 2-3 days (before bottling) to clarify the beer, but have read on forums that 2 weeks is what is required. Here is my plan...

Someone frist tells me how long I should wait for the gelatin to do its job. I wait that time, then rack into a tertiary.

Make a 2L wort from DME, throw in some lager yeast and ferment at 10C until it reches krausen stage. At the same time raise the temp of my brew to 10 C.

When the brew is at 10 C and the starter hits high krausen, drop it in.

Hope the yeast demolish the diacetyl.

1 week later, or when the activity drops of, drop the temp back down to 4 C.

One week after that prime and bottle condition at 10C for 4 weeks.

Then drink it.

Any one think this will work?

 

[boo boo]

It should work, but keep in mind the posibility of introducing
O2 into your brew at this stage.

 

[nabs478]

Will that be a problem if I am also putting in krausen beer? Wont the yeast remove it all with the diacetyl

 

[blefferd]

i brewed a pilsner urquell clone this spring and didnt perform my diacetyl rest properly, and ended up with a very very buttery beer tasted like popcorn well after reading up on how they brew pislner urquell the PU brewery does not perform a diacetyl rest. so instead of dumping the beer and from some coaxing from the guys on the boards i decided to keep it and 4 months later its starting to have less and less of a buttery taste.

next pilsner i make though im going to perform a diacetyl rest that butter taste almost made me puke lol and it sure does take along time for it to go away!

 

[nabs478]

i brewed a pilsner urquell clone this spring and didnt perform my diacetyl rest properly, and ended up with a very very buttery beer tasted like popcorn well after reading up on how they brew pislner urquell the PU brewery does not perform a diacetyl rest. so instead of dumping the beer and from some coaxing from the guys on the boards i decided to keep it and 4 months later its starting to have less and less of a buttery taste.

next pilsner i make though im going to perform a diacetyl rest that butter taste almost made me puke lol and it sure does take along time for it to go away!

I assume in that case, that if you bottle condition it a little warmer than the primary fermenting temp, say 15 C (59 F), it will consume the diacetyl faster?

I just bottled a small batch of beer last night that was in a carboy, and I hadnt tasted it. When I was done bottling, I tasted it, it had the some taste...bloody diacetyl! I added a little more yeast along with some glucose to make sure it gets fizzy enough, but after reading the above post, I am wondering what temp would be the best for conditioning.

 

[blefferd]

Pilsner Urquell says on there site (i beleve thats where i read it) they lager there beer at around 31 f. i was told i could sit my keg out let it warm up to room temp for a few days and it would go away i tried that and it seemed like it helped a little but still had the taste. i just keep letting it sit and sit lol and try it every now and then, slowly but surley its going away!

my next one will defently have a diacetyl rest takes to damm long to get rid of the taste the old school way lol