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Author Topic: Diacetyl Rest do-over?  (Read 1049 times)

Offline ScallyWag

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Diacetyl Rest do-over?
« on: January 29, 2022, 10:28:25 am »
I am in the process of making a couple of lagers as part of a split-batch experiment; one is Diamond Lager and the other is S-189.  Both were fermented for 10 days at 52F (climbing to 54F through their own metabolic heat, then dropping back to 52F on their own), and had both completed chewing up their sugars. (I'm guessing they were done at 6-8 days, but I gave them a few extra days.)

After 10 days, I raised the temperature to 60F for the diacetyl rest, for about 48 hours.  Then, into the fridge where they are now, at 35F.

Now, this is my very first attempt at a lager...  and I'm second-guessing myself.  Did I raise the temp high enough (and long enough) for the D-rest?  And how would I know?  I don't detect any sulfur smells, but I don't know if that is probative necessarily, and I don't have enough experience to know if I would know.

Also, would it be bad/good for me to pull them out of the fridge, let them free rise slowly back up to 55F or so, then put them into a 65F-ish area for a few more days to make sure the D-rest is complete?

Or should I just leave them at 35F for a long time an patiently wait/trust?

I'm not much of a connoisseur, and it should probably be drinkable (for me) regardless, but I do like it when my beers surprise me with great quality.

Offline majorvices

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Re: Diacetyl Rest do-over?
« Reply #1 on: January 29, 2022, 11:31:42 am »
If the beer doesn't taste or smell like diacetyl then you don't need a diacetyl rest.

Your temp was definitely high enough. Possibly long enough it just depends. I normally start my lagers off cold (48-52) and then finish the fermentation at around 58 until it is finished.


Offline denny

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Re: Diacetyl Rest do-over?
« Reply #2 on: January 29, 2022, 11:58:39 am »
There is no magic temp or time for a d rest.  The objective is to make the yeast more active to consume the d, and there is no specific temp or time to do that.  AAMOF, I seldom need a d rest because I give the yeast plenty of time to work at low temps. Ad Keith said, if you don't taste d, you don't need the rest.
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Offline Steve Ruch

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Re: Diacetyl Rest do-over?
« Reply #3 on: January 30, 2022, 07:55:58 am »
There is no magic temp or time for a d rest.  The objective is to make the yeast more active to consume the d, and there is no specific temp or time to do that.  AAMOF, I seldom need a d rest because I give the yeast plenty of time to work at low temps. Ad Keith said, if you don't taste d, you don't need the rest.
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Offline ScallyWag

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Re: Diacetyl Rest do-over?
« Reply #4 on: January 30, 2022, 08:38:37 am »
Thanks guys.  My guess is they should be fine.  Both yeasts chugged through much faster than I expected.  As a lager-virgin ;D, I don't know what to compare my performance against.  ("Was that long enough?")

I have never [knowingly] tasted diacetyl, so I'm not sure I'd know it if I did. 

I didn't try a taste of either one yet; I normally don't taste my brews until bottling (and sometimes not even then).  I suppose I probably should... 

When I first started brewing, a number of brews were nasty or disappointing, only to become wonderful several weeks down the road.  So I quit tasting them when still 'green' and just learned to trust the aging process.

Offline majorvices

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Re: Diacetyl Rest do-over?
« Reply #5 on: January 30, 2022, 09:06:08 am »
Diacetyl tastes different to different people. Some people are not very sensitive to it. Others are extremely sensitive to it. For some it tastes and smells like butter-flavored microwave popcorn -- and that butter flavor actually comes from the chemical diacetyl. For me, in beer, diacetyl can taste like rancid butter. I find it extremely unpleasant

Offline denny

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Re: Diacetyl Rest do-over?
« Reply #6 on: January 30, 2022, 09:59:12 am »
Diacetyl tastes different to different people. Some people are not very sensitive to it. Others are extremely sensitive to it. For some it tastes and smells like butter-flavored microwave popcorn -- and that butter flavor actually comes from the chemical diacetyl. For me, in beer, diacetyl can taste like rancid butter. I find it extremely unpleasant

I detect it as a slick mouthfeel.
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Offline majorvices

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Re: Diacetyl Rest do-over?
« Reply #7 on: January 30, 2022, 10:06:51 am »
That too.

Offline fredthecat

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Re: Diacetyl Rest do-over?
« Reply #8 on: January 30, 2022, 11:19:10 am »

Or should I just leave them at 35F for a long time an patiently wait/trust?


im on the 2nd batch of diamond lager this winter, and the first one i rushed to a degree ive never done before with a lager. it was a big mistake.

i know a lot of people have really short fermentation schedules and say it works. maybe it does on their system, but my two cents are - if in doubt - wait. this 2nd batch im letting sit for a full 6 weeks (at mid 50s) to clean up. the first one was 3 weeks then bottled and it didnt turn out well.




Offline majorvices

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Re: Diacetyl Rest do-over?
« Reply #9 on: January 30, 2022, 11:47:09 am »

Or should I just leave them at 35F for a long time an patiently wait/trust?


im on the 2nd batch of diamond lager this winter, and the first one i rushed to a degree ive never done before with a lager. it was a big mistake.

i know a lot of people have really short fermentation schedules and say it works. maybe it does on their system, but my two cents are - if in doubt - wait. this 2nd batch im letting sit for a full 6 weeks (at mid 50s) to clean up. the first one was 3 weeks then bottled and it didnt turn out well.

No one should have a "short fermentation schedule" for brewing lagers. The beer is done fermenting when it is done fermenting. It is usually pointless to lager for more than a couple of weeks for most lagers since nothing "magical" happens during the lagering period except for clarity. The exception may be for higher gravity lagers same as with higher gravity ales. Age can mellow out some fusels, etc., created during high gravity fermentation.

Offline ScallyWag

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Re: Diacetyl Rest do-over?
« Reply #10 on: January 30, 2022, 12:35:41 pm »
Again, thanks.  I really appreciate the input, guys.  I'll give each a tiny taste tonight with some NFL football.   :)

I am not in a hurry, so I may take them out of the fridge, and return them to their original fermenting spot (52F) for another couple of weeks (or three).  Yeah, they may not need it, but it shouldn't hurt them...  and could help them.  Nothing to lose, right?

They have only been at 35F for a couple of days.

Offline majorvices

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Re: Diacetyl Rest do-over?
« Reply #11 on: January 30, 2022, 01:37:21 pm »
I'm not sure why you would do that. One the beer is fermented and finished lagering it is ready to drink. Warming them up won't accomplish anything unless you don't think they are carbbed enough. If that is the case you need to warm them to room temp.

Offline denny

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Re: Diacetyl Rest do-over?
« Reply #12 on: January 30, 2022, 03:23:33 pm »
I'm not sure why you would do that. One the beer is fermented and finished lagering it is ready to drink. Warming them up won't accomplish anything unless you don't think they are carbbed enough. If that is the case you need to warm them to room temp.

Like Keith said, likely pointless. But if do detect d, you could krausen them. But don't do it if there's no diacetyl.
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Offline purduekenn

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Re: Diacetyl Rest do-over?
« Reply #13 on: January 30, 2022, 05:34:28 pm »
Diacetyl tastes different to different people. Some people are not very sensitive to it. Others are extremely sensitive to it. For some it tastes and smells like butter-flavored microwave popcorn -- and that butter flavor actually comes from the chemical diacetyl. For me, in beer, diacetyl can taste like rancid butter. I find it extremely unpleasant

I detect it as a slick mouthfeel.
I also get a slick sensation in my mouth and teeth as I can't taste Diacetyl.

Offline ScallyWag

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Re: Diacetyl Rest do-over?
« Reply #14 on: January 31, 2022, 09:54:24 am »
I don't detect any weird flavors, so I guess they're fine.  Pretty damn good, actually.  I'll probably bottle them up in a week or so.

I can't wait to compare these to the 5 ales that I made from the same batch.  I'll be sure to post about that tasting experiment when we get there.